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G E R T A I

O F THE

ANIMAL (ECONOMY,

by john hunter,

LONDON,
SOLD AT N° 13, CASTLE-STREET, LEICESTER-SQUARE.

MDCCLXXXVI»

SIR JOSEPH BANKS, BART.

PRESIDENT OF THE ROYAL SOCIETY,

&c, &c, &c.

DEAR SIR,

As the following Observations

were made in the Courfe of thofe Purfuits in which you

<

have fo warmly interefted yourfelf, and promoted with
the moft friendly Affiftance, 1 fhould be wanting in
Gratitude, were I not to addrefs them to you, as a public
Teftimony of the Friendship and Efteem with which I am,

DEAR SIR,

YOUR OBLIGED, AND
Leicester-square, VERY HUMBLE SERVANT,

november, 9j i786.

JOHN HUNTER.

THE

CONTENTS.

A Description of the fituation of the teftis in the fetus, with its
defcent into the fcrotum, page i

Observations on the glands iituated between the rectum and bladder,
called veficulas feminales, 27

An account of the free martin, 45

An account of an extraordinary pheafant, 6 3

An account of the organ of hearing in fifhes, 69

An account of certain receptacles of air in birds, which communicate
with the lungs and Euftachian tube, 77

Experiments and obfervations on animals, with refpedt to the power
of producing heat, 87

Proposals for the recovery of perfons apparently drowned, , 115

On the flru&ure of the placenta, page 127

Obfervations on the placenta of the monkey, 1^6

Observations on the Gillaroo trout, commonly called in Ireland the
gizzard trout, 141

Some obfervations on digeftion, 147

On a fecretion in the crop of breeding pigeons, for the nouriftiment of
their young, 191

On the colour of the pigmentum of the eye in different animals, 199
The ufe of the oblique mufcles, 209

-A defcription of the nerves which fupply the oxgall of fmelling, 213
A defcription of fome branches of the fifth pair of nerves, 219

ERRATA.

Page 14, line 2, for invariable, read invariably.
28, 25, for falling a, read falling from a,
63, 23, fox principle, read principal.
81, 15, for the humeri, read the os humeri.
88, i, for freeze, read froze,
lOl, I, for affeSl, read effect.
118, 19, for principle, read principal.

120, laft line, for roufes and depreffes, read roufe and deprefs.

187, line 13, for fwallows, read they fwallow.

A DESCRIPTION

[ * J

a description of the situation of the

testis in the foetus, with its descent
into the scrotum.

ADifcovery in any art not only enriches that to which it immediately
belongs, but elucidates all. thofe to which it has any relation. A.
knowledge of the conftruftion of the human body is effential to medicine,
therefore every improvement in anatomy muff throw new light on that
branch of fcience; and thefe improvements are more ftriking when they
are new; which is well illuftratea by the advantages derived to pathology,
from the difcovery of the lymphatics being the abforbent fyftem ; and is
no lefs evident in the hernia, where the inteftine lies in contact with the
tefhVlo, whirh by the difcovery of the original feat of the tefticleis perfectly
explained.

Several years before Haller\'s Opufcula Patholbgica were publiOied, my
brother informed me, that in examining the contents of the abdomen of a
child, ftill born,, about the feventh or eighth month, he found both the
tefticles lying in that cavity, and mentioned the circumftance with fome
degree of furprife. We could never explain this matter to our fatisfa&ion
till the publication of the Opufcula, to which Dr. Hunter alludes,, com-
mentaries, page 72, in the following words..

" In the latter end of the year 1755, when I firft had the pleafure of
reading Baron Haller\'s obfervations on the hernia congenita,² it ftruck my
imagination that the flate of the teftis in the foetus and. its defcent. from
the abdomen into the fcrotum would explain feveral things concerning
ruptures and the hydrocele, and particularly that obfervation which Mr.
Sharp had communicated to me, viz. that in ruptures the inteftine is
fometimes in contact with the teftis. I communicated my ideas upon
this fubject to my brother, and defired that he would take every opportu-

» Alberti Halleri Opufcul. Patholog. Laufan, 1755, 8vo. page 53, &c,

B nity

nity of learning exactly the Hate of the teftis before and after birth, and
the ftate of ruptures in children. We were both convinced that the exa-
mination of thofe fads would anfwer our expectation, and both recollected
having feen appearances in children, that agreed with our fuppofition, but
faw now that we had negleCted making the proper ufe of them.

" In the courfe of the winter, my brother had feveral opportunities of
differing foetufes of different ages, and of making fome drawings of the
parts ; and all his obfervations agreed with the ideas I had formed of the
nature of ruptures, and of the origin of the tunica vaginalis propria in the
fœtus. But till thofe obfervations were repeated to his fatisfadion, and
were fufficiently afcertained, he deli red me not to mention the opinion in
my ledure ; and therefore, when treating of the coats of the teftis, and of
the fituation of the hernial fac, &c. I only put in this temporary caution,
that I was then fpeaking of thofe things as they are commonly in adult
bodies, and not as they are in the foetus : and at laft, when I was conclu-
ding my ledures for that feafon in the end of April. T756, with a courfe
of the chirurgical operations, I gave a very general account of my brother\'s
obfervations, and fhewed both the drawing of Fig. II. which was then
finished, and the fubjed from which it was made."

The following obfervations on this fubjed are taken from my notes,
published by Dr. Hunter, in his commentaries, to which I have fince
added fome practical remarks.

Until the approach of birth, the teftes of the foetus are lodged within
the cavity of the abdomen, and may therefore be reckoned among the ab-
dominal vifcera.

They are fituated immediately below the kidneys, on the forepart of the
pfose mufcles, and by the fide of the reCtum, where this inteftine is paffing
down into the cavity of the pelvis : for in the foetus the redum, which is
much larger in proportion to the capacity of the pelvis, than in the full-
grown fubjed, lies before the vertebrae lumborum as well as before the os
facrum. Indeed the cafe is pretty much the fame with regard to all the
contents of the pelvis ; that is, their fituation is much higher in the foetus
than in the adult 5 the figmoeide flexure of the colon, part of the redum,
the greateft part of the bladder, the fundus uteri, the fallopian tubes,

&c.

&c. being placed in the foetus above the hollow of the pelvis, in the com-
mon or great abdominal cavity.

At this time the fhape or figure of the teftis is much the fame as in
the adult, and its pofition or attitude is the fame as when it is in the fcro-
turn that is, one end is placed upwards, the other downwards ; one flat
fide is to the right, the other to the left -, and one edge is turned back-
wards, the other forwards. But as the teftis is lefs connected with the
furrounding parts while it is in the loins, its pofition may be a little va-
riable. The moft natural feems to be when the anterior edge is turned
directly forwards ; but the leaft touch of any thing will throw that edge
either to the right fide, or to the left, and then the flat fide of the teftis is
turned forwards.

It is attached to the pfoas mufcle all along its pofterior edge, except juft
at its upper extremity. This attachment is formed by the peritonaeum,
which covers the teftis and gives it a fmooth furface, in the fame manner
as it envelopes the other loofe abdominal vifcera.

The epididymis lies along tne ouinac ur aie poitenor edge or trie teftis,
as in older bodies,, but is larger in proportion, and adheres backwards to
the pfoas. When the foetus is very young, the adhefion of the teftis and
epididymis to the pfoas is very narrow ; and then the teftis is more loofe,
and more proje<fting ; but as the fœtus advances in months, the adhefion
of the teftis to the pfoas becomes broader and tighter.

The veffels of the teftis, like thofe of moft parts of the body, commonly
rife from the neareft larger trunks, viz. from the aorta and cava, or from
the emulgents.

The artery generally rifes from the forepart of the aorta, a little below
the emulgent artery ; and often from the emulgent itfelf, efpecially in the
right fide of the body ; which may happen the rather, becaufe the trunk
of the aorta is more diftant from the right teftis than from the left. Some-
times, but much more rarely, the fpermatic artery fprings from the phrenic,
or from that of the capfula renalis. Befides the artery which riles from
the aorta, or emulgent, &c. the teftis receives one from the hvpogaftric
artery, which is fometimes as large as the other. It runs upwards from
its origin, pafiing clofe to the vas deferens, in its way to the teftis. The

B 2 fuperior

fuperior fpermatic artery fometimes paffes before the lower end of the kid-
ney. Both thefe arteries run in a ferpentine direction, making pretty large
but gentle turnings; both are fitu ted behind the peritonaeum, and both
run into the pofterior edge of th- teftis, between the two reflected laminas
of that membrane, much in the fame manner as the vefTels pafs to the in-
teftines between the two reflected laminas of the mefocolon or mefentery.
■ The veins of the teftis are analogous to its arteries. The fuperior fper-
matic vein, to begin with its trunk, rifes commonly in the following man-
ner ; on the right fide from the trunk of the cava a little below the
emulgent, and on the left fide from the left emulgent vein. The reafon
of this difference between the right and left fpermatic vein, no doubt, is
becaufe the cava is not placed in the middle of the body -, fo that by the
rule of ramification, which is obferved in moft parts of the body, the cava
is the neareft large vein of the right fide, and the emulgent is the neareft
large vein of the left lide. But the difference is inconliderable ; and ac-
cordingly we fometimes find the right fpermatic vein coming from the
right emulgent vein, and ieveral other varieties, which, fo far as I can
©bferve, follow no precife rule. There is likewife a fpermatic vein, which
rifes from the internal iliac, and runs up to the teftis with the inferior
fpermatic artery. Both the fpermatic veins run behind the peritoneum
with their correfponding arteries, and go into the pofterior edge of the
teftis, where they are loft in fmall branches.

The nerves of the teftis, like its blood-veffels, come from the neareft
four.cethat is, from the abdominal plexufes of the intercoftal; efpecially
the inferior rnefenteric plexus. They run to the teftis, attending upon its
blood-veffels, and are difperfed with them through its fubftance. The
teftis therefore, with refpect to its nerves, may be reckoned an abdominal
vifcus ; and this obfervation will hold good, when applied to the full-
grown fubjed, as well as to the fœtus ; for thofe branches of the lumbar
nerves, which are commonly faid to be fent to the teftis, pafiing through
the tendon of the external oblique mufcle, in reality go not to the teftis
itfelf, but to its exterior coverings, and to the fcrotum.

The tefticle receiving its nerves from the plexufes of the intercoftal,
accounts for the ftomach and inteftines fympathifing fo readily with it

and

tnd its particular fenfation, with the elects arifing in-the conftitution upon
its being injured.

The epididymis begins at the outer and pofterior part of the upper end
of the teftis, immediately above the entrance of the blood-veffels. There
it is thick, round, and united to the teftis; as it paffe.s down, it becomes
a little fmaller and more flat, and is only attached backwards to the teftis,
or rather indeed to its veffels, for it lies loofe againft the fide of the teftis
forwards; and at its lower end it is again more firmly attached to the body
of the teftis ; fo that in the fcetus there is a cavity or pouch formed between
the middle part of the teftis, and the middle part of the epididymis, which
is more confiderable than what is commonly obferved in full-grown fub-
jedts. As the body grows, the epididymis adheres more clofely to the fide
of the teftis. The greateft part of the epididymis is made up of one con-
voluted canal, which becomes larger in fize and lefs convoluted towards
the lower end of the epididymis, and at laft is manifeftly a fingle tube run-
ning a little ferpentine. That change happens at the lower end of the
teftis, and there the canal taK.es tiie name uf vm ucitmia.

This du£t is a little convoluted or ferpentine in its whole courfe, but
is lefs fo as it comes nearer to the bladder; inftead of running upwards
from the lower end of the teftis, as it does at a more advanced period of
life, in the foetus at this age it runs downwards and inwards in its whole
courfe; fo that it goes on almoft in the direction of the epididymis, of
which it is a continuation. It turns inwards from the lower end of the
epididymis, under the lower end of the teftis, and behind the upper end
of a ligament or gubernaculum teftis, which I fhall prefently defcribe;
then it paffes over the iliac veffels and over the infide of the pfoas muf-
cle, fomewhat higher than in adult bodies; and at laft goes between the
uretei^and bladder towards the bafis of the proftate gland.

In thofe animals where the tefticles change their fituation, the cremafter
mufcle, which fhould be named mufculus teftis, has two very different po-
fitions in the foetus, and in the adult; the firft of thefe is, the fame as in
thofe animals whofe tefticles remain through life in the cavity of the
abdomen; we muft therefore conclude that the fame purpofes are anfwered
by this mufcle in the foetus, as in thofe animals.

The

The ufe of this mufcle, when the tefticle is in the fcrotum, appears to
be evidently that of a fufpenfory : but what purpofe it anfwers in the foetus,
or in animals whofe tefticles remain in the abdomen, is not eafily imma-
gined, there being no apparent reafon why fuch a mufcle fhould exift.

The cremafter or mufculus teftis appears to be compofed of the lower
fibres of the obliquus internus and tranfverfalis mufcles in the foetus,
turning upwards inftead of going acrofs to the pubis and fpreading upon
the external furface of the gubernaculum immediately under the perito-
naeum j it appears to be loft on the peritonaeum, a little way from the
tefcicle; this is more evidently feen in adult fubje£ts who have had a hy-
drocele, or rupture; in- fuch cafes the mufcle becomes ftronger than ufual,
and its fibres can be traced fpreading on the tunica vaginalis, and feem
at laft to be loft upon it near to the lower end of the body of the tefticle.

The nerves which fupply this mufcle are probably branches from the
nerves of the obliquus internus and tranfverfalis mufcles, for the fame caufe
which throws the abdominal mufcles into action produces a fimilar effedt
on the mu&ulus teftis, which circumitance appears to be moft remarkable
in the young fubjedl. When we cough or a<5t with the abdominal muf-
cles we find the tefticles to be drawn up j the mufculus teftis and abdom-
inal mufcles obeying the fame command of the will.

At this time of life the teftis is connected in a very particular manner
with the parietes of the abdomen, at that place where in adult bodies the
fpermatic veffels pafs out, and likewife with the fcrotum. This connection
is by means of a fubftance which runs down from the lower end of the
teftis to the fcrotum, and which at prefent I fhall call the ligament, or
gubernaculum teftis, becaufe it connects the teftis with the fcrotum, and
dire&s its courfe in its defcent. It is of a pyramidal form; its large
bulbous head is upwards and fixed to the lower end of the teftis and
epididymis, and its lower and flender extremity is loft in the cellular mem-
brane of the fcrotum. The upper part of this ligament is within the
abdomen, before the pfoas, reaching from the teftis to the groin, or to
where the fpermatic veffels begin to pafs through the mufcles. Here the
ligament runs down into the fcrotum precifely in the fame manner as the
fpermatic veffels pafs down in adult bodies* and is there loft.. The lower

part

part of the round ligament of the uterus in a fœtus very much refembles
this ligament of the teftis ; and may be plainly traced down into the
labium, where it is imperceptibly loft. That part of the ligamentum teftis,
which is within the abdomen, is covered by the peritonaeum all round,
except at its pofterior part, which is contiguous to the pfoas, and con-
nected with it by the reflected peritoneum, and by the cellular membrane.
It is hard to fay what the ftruCture or compofition of this ligament may
be. It is certainly vafcular and fibrous, and the fibres run in the direction
of the ligament itfelf. It is covered by the fibres of the cremafter or
mufculus teftis which is placed immediately behind the peritoneum ;
this is not eafily afcertained in the human fubjeCt, but is very evident in
other animals, more efpecially in thofe whofe tefticles remain in the ca-
vity of the abdomen after the animal is full-grown.

In the hedge-hog tïie teftes continue through life to be lodged within
the abdomen, in the fame fituation as in the human fœtus ; and they are
1 aliened hj tk® kind of ligament to the infide of the oarietes of the
abdomen at the groin. Now, in that animal, I find that the lowermoffc
fibres of the internal oblique mufcle, which conftitute the cremafter, are
turned inwards at the place where the fpermatic veffels come out in other
animals, making a fmooth edge or lip by their inverfion ; and that then
they mount up in the ligament to the lower end of the teftis. Sometimes
in the human body, and in many other animals, and very often in fneep,
the teftes do not defcend from the cavity of the abdomen till late in life,
or never at all. In the ram, where the teftis is come down into the
fcrotum, the cremafter is a very ftrong mufcle ; and, though it be placed
more inwards at its beginning, it pafles down pretty much as it does in
the human body, and is loft on the outfide of the tunica vaginalis ; but in
the ram, whofe teftis remains fufpended in the abdominal cavity, I find
that the fame cremafter exifts, though it is a weaker mufcle ; and inftead
of paffing downwards, as in the former cafe, it turns inwards and up-
wards, and is loft in the peritoneum that covers the ligament which
attaches the teftis to the parietes of the abdomen, and which in this
ftate of that animal is about an inch and an half in length. In the
human fœtus, while the teftis is retained in the cavity of the abdomen,

the

the cremafter is fo flender that I cannot trace it to my own fatisfadtiorjy
either turning up towards the teftis or turning down towards the fcrotum,.
Yet from analogy we may conclude that it paffes up to the tefticle, fince
in the adult we find it inferted or loft on the lower part of the tunica va-
ginalis, in the fame manner as in the adult quadruped.

The peritonaeum, which covers the teftis and its ligament or guberna-
culum, is firmly united to the furfaces of thofe two bodies; but all around,
to wit, on the kidney, the pfoas, the iliacus interims, and the lower part
of the abdominal mufcles, that membrane adheres very loofely to all the
furfaces which it covers. Where the peritonaeum is continued or reflected
from the abdominal mufcles to the ligament of the teftis, it paffes
firft downwards a little way, as if palling out of the abdomen, and then
upwards, fo as to cover more of the ligament than what is within the
cavity of the abdomen. At this place the peStonaeum is very loofe,
thin in. its fubftance, and of a tender gelatinous texture; but all around
the paflage of that ligament the peritonaeum is confiderably tighter, thicker,
and of a more firm texture. When the abdominal mufcles are pulled up
fo as to tighten and ftretch the peritonaeum, this membrane remains-.loofe
at the paflage of the ligament, while it is braced or tight all around; and
in that cafe the tight part forms a kind of border or edge around the loofe
doubled part of the peritonaeum, where the teftis is afterwards to pafs. This
loofe part of the peritonaeum, like the intro-fufcepted gut, may, by draw-
ing the teftis upwards, be pulled up into the abdomen, and made tight;
and then there is no appearance of an aperture or paffage down towards
the fcrotum : but when the fcrotum and ligament are drawn downwards,
the loofe doubled part of the peritonaeum defcends with the ligament, and
then there, is an aperture from the. cavity of the abdomen all around the
forepart of the ligament, which feems ready to receive the teftis. This
aperture becomes, larger when the teftis defcends lower, as if the pyramidal
or wedge-like ligament was firft drawn down, in order not only to dired:
but. to make room for the teftis which muft follow it. In fome foetufes
I found the aperture fo large, that I could pufh the teftis into it, as
far as the tendon of the external oblique mufcle, .

From this original fituation within the abdomen the teftis is afterwards
moved to its deftined ftation in the fcrotum. It is the more difficult to
afcertain the exadt time of this motion, as we hardly ever know the exadt
age of our fubjedt. According to the obfervations which I have made, it
feems to happen fooner in fome instances than in others, but generally
about the eighth month. In the feventh month I have commonly found
the teftis in the abdomen, and in the ninth I have as commonly found it
in the upper part of the fcrotum. The defcent being thus early and the
paftage being almoft immediately clofed is the principal means of prevent-
ing the hernia congenita.

At the before mentioned period, the teftis moves downwards till its-
lower extremity comes into contadt with the lower part of the abdominal
parietes. By this time the upper part of the ligament, which hitherto
was within the abdomen, has funk downwards, lies in the paftage from
the abdomen to the fcrotum, and lies in that paffage which is afterwards
to receive the teftis. As the tefticle paffes out, it in fome degree inverts the
fituation of the ligament palling down uenmci iu wnat was the anterior
furface of the ligament while in the abdomen now becoming pofterior and
compofing the lower and anterior part of the tunica vaginalis on which the
mufculus teftis is loft: this is more evident in thofe animals whofe
tefticles readily pafs from the abdomen to the fcrotum. The place where
the ligament is moft confined, and where the teftis meets with moft
obftrudtion in its defcent, is the ring in the tendon of the external
oblique mufclej and accordingly I think we fee more men who have
one teftis, or both, lodged immediately within the tendon of that muf-
cle, than who have one or both ftill included in the cavity of the ab-
domen, which I fhall take notice of hereafter.

After the teftis has got quite through the tendon of the external
oblique mufcle, it may be confidered as pofteffing its determined ftation
though it commonly remains for fome time by the fide of the penis,,
and by degrees only defcends to the bottom of the fcrotum. And when
the teftis has defcended entirely into the fcrotum, its ligament is ftill con-
nected with it, and lies immediately under it, but is /hortened and com-
prelTed,

C

Having now given an account of the original fituation of the teftes, of
the time of their defcent from the abdomen, and of the route which they
take in their removal to the fcrotum, I fhall in the next place defcribe the
manner in which they carry down the peritoneum with them, and then
explain how that membrane forms the fac of the hernia congenita in fome
bodies, and the tunica vaginalis propria in others.

When the teftis is defcending, and when it has even pafTed into the
fcrotum, it is ftill covered by the peritoneum, exactly in the fame manner
as when it was within the abdomen ; and the fpermatic veffels run down
behind the peritoneum there, as they did when the teftis lay before the
pfoas mufcle j and that lamella of the peritoneum js united behind with
the teftis, the epididymis, and the fpermatic veffels (befides the vas de-
ferens) as it was in the loins; and the teftis is fixed backwards to the
parts againft which it refts, and is unconnected and loofe forwards, as it
was when in the abdomen. In coming down the teftis brings the peri-
toneum with it; and the elongation of that membrane, though in fome
circumftances it be like a common hernial lac, yet in others is very dif-
ferent. If we can imagine a common hernial fac reaching to the bottom
of the fcrotum, and covered by the cremafter mufcle, and that the pofte-
rior half of the fac covers, and is united with, the teftis, epididymis,
fpermatic veffels, and vas deferens, and that the anterior half of the fac
lies loofe before all thofe parts, it will give a perfeCt idea of the ftate of
the peritoneum, and of the teftis when it comes firft down into the
fcrotum. The teftis therefore in its defcent does not fall loofe, like the
inteftine or epiploon, into the elongation of the peritonaeum but it Hides
down from the loins, carrying the peritoneum with it; and both itfelf
and the peritoneum continue to adhere by the cellular membrane to the
parts behind them, as they did when in the loins. This is a circumftance
which I think may be eafily underftood; and yet I Ihould fuppofe that
It may not be fo very intelligible, becaufe I find ftudents very generally
puzzled with it, and imagine that, when the teftis comes firft down, it
ihould be loofe all around, like a piece of the gut or epiploon in a common;
hernia. The duCtility of the peritoneum, and its. very loofe connection
by a. flight cellular membrane to the pfoas, and to all the other parts

around;

around the teftis, are circumftances which favour its elongation and
defcent into the fcrotum with the teftis. This peculiarity of defcent often
takes place in fome of the inteftines ^ but it can only happen in thofe
which have adhefions to the loins. This I fufped: to be rather the con-
iequence of a rupture already formed, than the caufe of the firft forma-
tion of the hernial fac, in which the inteftine lies, and I fhould fuppofe
could only form very gradually. The caecum has been fometimes found
to have defcended into the fcrotum, and to have brought along with it
its adhefions through its whole courfe : the fame thing has happened to
the figmoide flexure of the colon ; and I have found the whole of it in
the left fide of the fcrotum, with its adhefions brought down from the
loins. Such hernia; cannot be reduced ; and in cafe of ftrangulation are
not to be operated upon in the common way; the fac fliould not be
opened, but the ftri&ure divided, and the newly protruded part reduced.

It is plain from this defcription, that the cavity of the bag, or of the

elongation of the peritonaeum, which contains the teftis in the fcrotum,
muft at firft communicate wrai uic g^uciiu cavity ur uic *bUvmcn, by

an aperture at the infide of the groin. That aperture has exa&ly the
appearance of a common hernial fac : the fpermatic veflels and vas defe-
rens lie immediately behind it, and a probe pafles readily through it from
the general cavity of the abdomen down to the bottom of the fcrotum«
And if this procefs of the peritoneum be laid open through its whole
length on the forepart, it will be plainly feen to be a continuation of the
peritonaeum ; the teftis and epididymis will be feen at the lower part of
it ; and the fpermatic veflels and the vas deferens will be feen covered by
the pofterior part of the bag, in their whole courfe from the groin to the
teftis.

Thus it is in the human body, when the teftis is recently come down *
and thus it is, and continues to be through life, in every quadruped
which I have examined, where the teftis is in the fcrotum ; but in th@
human body the communication between the fac and the cavity of the
abdomen is foon cut off : indeed I believe that the upper part of the fac
naturally begins to contract as foon as the teftis has pafled through
the mufcles. This opinion is grounded on the following obiefvation,

C 2 I have

I have feen an inftance where from the age of the fcetus and from every
other mark, it was probable that the teftis was very recently come down,\'
and yet the upper part of the fac was very narrow : I pufhed the teftis
upwards, in order to fee if it could be returned; the attachments of the
teftis eafily admitted of its afcent, and fo did the aperture in the tendon of
the external oblique mufcle; but the orifice and upper end of the fac would
not, by any means, admit of the teftis being puflied quite up into the ab-
domen. However this may be, the upper end of the fac certainly con-
traits, and unites firft, and is quite clofed in a very fhort fpace of time;
for it is feldom that any aperture remains in a child born at its full time;
and this contraction and union is continued downwards till it comes near
the tefticle, where the difpofition for fuch an operation does not exift,
leaving the lower part of the fac open or loofe, even in the human fubjecSt,
through life, and forms the tunica teftis vaginalis propria, the common
feat of an hydrocele. Many cafes of hydrocele in children feem to prove
that the progrefs of this contraction and union is downwards, for in them
the water commonly extends higher up the chord than in the adult,
except in thofe of a confiderable fize; but in fome children this union
feems not to take place regularly, but is interrupted in the middle, produ-
cing an hydrocele of the chord, which neither communicates with the
abdomen or tunica vaginalis teftis. This contraction and obliteration of
the paftage feems to be a peculiar operation of nature, depending upon
fteady and uniform principles, and not the confequence of inflammation,
or of any thing that is accidental: and therefore, if it is not accomplished
at the proper time, the difficulty of bringing about an union of the part is
much greater; as in children who have had the fac kept open by a turn of
the inteftine falling down into the fcrotum immediately after the teftis.
This looks as if nature, from being baulked when £he was in the
humour of doing her work, would not, or could not fo eafily do it after-
wards. I fhall readily grant that what has been advanced here as a proof
of the doCtrine, may be explained upon other principles. This at leaft
is certain, that the clofing of the mouth, and of the neck of the fac, is
peculiar to the human fpecies; and we muft fuppofe the final caufe to
be the prevention of ruptures, to which men are fo much, more liable

than

than beafts, from their erect ftate of body. I11 fome cafes the aperture
of the fac is not entirely clofed, allowing a fluid to pafs down and form
a hydrocele, which fluid upon preffure can be fqueezed back into the
belly; cafes of this kind fometimes give the idea of a gut being pro-
truded, and make it difficult to determine the exaCt nature of the cafe.

What is the immediate caufe of the defcent of the teftis from the
loins to the fcrotum ? It is evident that it cannot be the compreffive
force of refpiration, becaufe commonly the teftis is in the fcrotum before
the child has breathed ; that is, the effect has been produced before the
fuppofed caufe has exifted. Is the teftis pulled down by the cremafter
mulcle ? I can hardly fuppofe that it is ; becaufe, if that was the cafe,
I fee no reafon why it Ihould not take place in the hedge-hog, as well
as in other quadrupeds ; and if the mufculus teftis had this power, it
could not bring it lower than the ring of the mufcle.

Why do the teftes take their blood-veffels from fuch diftant trunks ?
Thofe phyfiologifts, who have puzzled themfelves about the folution of
this queftion, have not ctmnacivu, /un <>r budy,

the teftes are fituated, not in the fcrotum, but immediately below the
kidneys ; and that therefore it was very natural that their blood-veffels
fhould rife in the fame manner as thofe of the kidneys, but a little lower.
The great length of the fpermatic veffels in the adult body will no
doubt occafion a more languid circulation, which, we may fuppofe, was
the intention of nature.

The fituation of the teftis in the fœtus may likewife account for the
contrary directions of the epididymis and of the vas deferens in adult
bodies, though thefe two in reality make only one excretory canal. I11
the fœtus the epididymis begins at the upper end of the teftis 3 and
it is natural, confidering it as an excretory tube, that it fhould run
downwards. And it is as natural that the reft of the tube, which is
called vas deferens, ihould turn inwards at the lower end of the teftis,
becaufe that is its moft direCt courfe to the neck of the bladder. Thus
we fee that in the fœtus the excretory duCt is always paffing down-
wards. But the teftis is directed in its defcent by the gubernaculum »
and this is firmly fixed to the lower parts of the teftis and epididymis,

and

and to the beginning of the vas deferens, and thence muft keep thofe
parts invariable in their fttuation with refpedt to one another: and there-
fore in proportion as the teftis defcends, the vas deferens muft afcend from
the lower end of the teftis j and it muft, from the pafTage through the ab-
dominal mufcles down to the teftis, run parallel with the fpermatic veffels.

The teftis, its coats, and the fpermatic chord, are fo often concerned in
fome of the moft important difeafes and operations of furgery, particularly
in the bubonocele and hydrocele, that their ftrudture has been examined
and defcribed by the furgeons, as well as by the anatomifts, of every age.
Yet the defcriptions of the cleareft and beft writers upon the fubjedt differ
fo much from one another, and many of them differ fo much from what
is obvious and demonftrable by diffedtion, that it would feem difficult to
account for fuch a variety of opinions. The very different ftate of the
parts in the quadruped, and in the human body, no doubt, muft have oc-
cafioned error and confufion among the writers of more antient times,
when the parts of the human body were defcribed from diffedtion s and ob-
servations made principally upon brutes : and the circumftances in the
ftrudlure of the parts, which are peculiar to the fcetus, having been im-
perfectly underftood, we may fuppofe, has likewife contributed to make
perplexity and contradiction among authors.

Baron Haller, in his Opufcula Pathologica, has obferved, that in infants,
fometimes the inteftine falls down into the fcrotum after the teftis, or along
with it, and occafions what he calls the hernia congenita. In fuch a cafe
the hernial fac is formed before the inteftine falls down, as that ingenious
anatomift has obferved. There are befides two very peculiar circumftan-
ces in a rupture of this kind; the inteftine is always in immediate contadt
with the teftis, and there is no tunica vaginalis propria teftis. The ftruc-
ture of the parts in the foetus explains, in the moft fatisfadlory manner,
both thofe circumftances, however extraordinary they muft appear to a
man who is only converfant with the ftrudlure of the parts in fubjedts of
a more advanced age : and indeed it is fo clear that it needs no illuftration.
I may obferve, however, that the hernia congenita may happen, not only
by the inteftine falling down to the teftis before the aperture of the fac be

clofed_?

clofed, but perhaps afterwards : for when the fac has been but recently
clofed, it feems poffible enough that violence may open it again.

It mull likewife be obvious to every anatomift, who examines the ft a te
of the teftis in children of different ages, that the mouth and neck only of
the fac clofe up, and that the lower part of the fac remains loofe around
the teftis, and makes the tunica vaginalis propria. Whence it is plain that
this tunic was originally a part of the elongated peritonaeum : and as that
tunic is undoubtedly the feat of the true hydrocele, it is alfo plain that the
hernia congenita and the true hydrocele cannot exift together in the fame
fide of the fcrotum ; for when there is a hernia congenita, there is no
other cavity than that of the hernial fac ; and that cavity communi-
cates with the general cavity of the abdomen..

The obfervations, contained in the two laft paragraphs, occurred to
my brother upon reading Baron Haller\'s Opufcula Pathologica, and gave
rife to my inquiries upon this fubjeéh

Ha ving given an account of the fituation of the tefticles in the foetus,
of their defcent, and the circumitances attending it, I fhall next confider

the cafes where this change takes place in one or both tefticles later than
the ufual or natural time : and having taken notice of the confequences of
this defcent when it happens at fo late a period, 1 fhall proceed to mention
thofe cafes in which the tefticles never pafs out of the abdomen..

I have laid, that the early coming down of the tefticles, and clofing of
the mouth of the fac, by ufually taking place before birth, hinder the
defcent of any part of the abdominal vifcera ; but when the tefticles re-
main in their firft fituation beyond this period, thefe advantages are loft y
a part of the inteftines or epiploon being liable to defcend. along with them.

The firft or natural procefs, in lome inftances, not having been begun,
or having been interrupted before birth, it becomes afterwards very uncer-
tain when the defcent will be compleated ; yet I think the completion
moft frequently happens between the years of two and ten, while the per-
fon is young and growing, being feldom delayed beyond the age of puberty.,
It is not eafy to afcertain the caufe of this failure in the defcent of the
tefticle ; but I am inclined to fufpeâ that the fault originates in the tef-
ticles themfelves ; it is however certain that the tefticle which has com-

pleated its defcent, is the largeft, which is more evident in the quadruped
than in the human fubjeCt • as in thefe we can have an opportunity of
examining the parts when we pleafe, and can determine how fmall, in
companion with the other, that tefticle is which has exceeded the ufual
time of coming; down: it never defcends fo low as the other.

O -*

The defcent of that tefticle is very flow, which is not compleated before
birth, often requiring years for that purpofe; it fometimes- never reaching
the fcrotum, efpecially the lower part of it. There is oftner I believe an
inequality in the fituation of the two tefticles than is commonly imma-
gined; they are feldom equally low in the fcrotum; and I am of opinion
that the loweft is the moil vigorous, having taken the lead readily and
come to its place at once: the part where it meets with the greateft
difficulty in its defcent, is in the divifion of the tendon of the external
oblique mufcle, called the ring.

How far an erect pofition of body, the action of the abdominal
mufcles, and the effect produced upon the contents of the abdomen in
breathing, may contribute mechanically to the defcent of the tefticles
when the natural operations of the animal ceconomy have failed, X will
not pretend to decide; but when we fee thefe combined actions produ-
cing an unnatural defcent of a portion of inteftine, we may conceive
that they are likewife capable of contributing to the defcent of the
tefticle.

When the tefticle has remained in the cavity of the abdomen beyond
the ufual time, it is impoffible to fay whether the difpofition for do-
ling up the paffage, after it has palled out, is in fome meafure loft or
not; but when it comes down after birth, we can eafily fiippofe fome
portion of inteftine or epiploon more ready to defcend and prevent the do-
ling of the mouth of the fac, than before the child was born when no fuck
actions had taken place; we fliould therefore watch this defcent of the
tefticle, and endeavour by art to procure that union which the natural
powers are either not difpofed to perform, or are prevented from compleat-
ing by the defcent of other parts. But art Ihould not be ufed too foon,
nor till the tefticle has got a little way below the ring. As this progrefs
is very flow, efpecially when-the tefticle is creeping through the ring, a

doubt

doubt often arifes in the mind, whether it is better entirely to prevent its
paffage, or to affift it by exercife or other means ; it would certainly be the
beft practice to affift it if that could be done effectually. When it has got
upon the outiide of the tendon it in general can be eafily pufhed up again
into the abdomen; and in thefe two fituations it will fometimes play back-
wards and forwards, for years, without ever coming low enough to allow
of the ufe of artificial means to prevent its defcent, or to prevent a rupture.
In this cafe it becomes difficult to determine what fhould be done ; but
from what I have feen I fhould be inclined to wait the defcent and give it
every affiftance in my power. Indeed in all cafes I would advife waiting
with patience; for in moft of thofe which I have feen, years have elapfed
from the firft appearance of the tefticle under the ring of the abdominal
mufcle before it has reached that fituation in which we may fafely apply
a trufs. I never perceived that any inconvenience arofe from waiting; and
the danger, if there is any, may be in fome degree avoided. I have always
recommended modp_ra fe. not violent exercife.

When the tefticle has got fome way below the ring then the cafe is to
be treated as an inguinal hernia, and a trufs applied upon the ring above
the tefticle; taking care the tefticle is not injured by it: but as this gene-
rally happens at too early a period for the patients themfelves to be able to
attend to it, it becomes the more necefiary that the furgeon who is em-
ployed fhould be very attentive, and that thofe who have the charge ©f
their education fhould watch them with particular care.

If it is thought advifable to prevent the tefticle from coming down, a
trufs is equally adapted for that purpofe, as for preventing the defcent of
an inteftine where there is an hernial, fac.

It fometimes happens that one of the tefticles remains in the cavity of
the abdomen through life, never afiuming the difpofition to change its
fituation when this happens, the perfon naturally concludes that he has,
only one tefticle; and it can only be know⁷n that he had two by an exami-
nation. of thefe parts after death : it is however poffible in fome inftan-
ces that one may be wanting ; but if we are to reafon from analogy,
we muft fuppofe this very feldom to be the cafe. As it is a very com-
« mon circumftance for many quadrupeds to have only one. tefticle in the

I> fcrotum₅

fcrotum, and in fuch which are killed for food, and from that circum-
ftance come more particularly under obfervation, we in general find the
other in the cavity of the abdomen; and in fome inftances they are
both found lying in that cavity.

When both tefticles remain through life in the belly, I believe that
they are exceedingly imperfeCt, and incapable of performing the natural
functions of thofe organs; and this imperfection prevents the difpofition
for their defcent taking place. They are more defective than thofe which
are late in coming into the fcrotum. This is very evident in the quad-
ruped, for in them the tefticle which has reached the fcrotum is con-
fiderably larger than that which remains in the abdomen. It is pro-
bable that it is a tendency towards an hermaphrodite, the tefticle feldom
being.well formed. In fuch cafes nothing is to be done by art; as it
is not poflible to give the ftimulus of perfection to fuch tefticles, which
I believe is neceffary to make them affume the difpofition which is re-
quifite for their defcent; and the ring of the external oblique mufcle is
probably lefs liable, in thefe inftances, to allow of the defcent of a
portion of inteftine than where the tefticles have palled through it ;
fuch perfons being perhaps more fecure from accidents of this kind than
if they had been more perfectly formed.

That the defcriptions which I have given may be better underftood I
have annexed three figures that were carefully taken from nature.

r ⁱ9 3

PLATE I.

THE firft figure reprefents the teftes within the abdomen, in an abortive
foetus of about fix months. All the inteftines, except the reCtum,
are removed; and the peritonaeum in nioft places is left upon the furfaces
which it covers, fo that the parts have not that fharpnefs and diftinCt ap-
pearance which might have been given to them by direction.
A The upper part of the obje&, covered with a cloth,
BB The thighs.
C The penis.
D The fcrotum.

E The flap of the integuments, abdominal mufcles, and peritonaeum,

turned back over the right os ilium to bring the teftis into view.
F The flap of the fkin and cellular membrane of the left fide difpofed in
the fame manner.

G The flap of the abdominal mufcles and of the peritoneum of the left
fide turned back over the fpine of the os ilium. The lower part of
this flap is cut away, in order to fhew the ligament of the teftis
paffing down through the ring into the fcrotum.
HH The lower part of each kidney.

I The projection formed by the lower vertebrae lumborum, and by the

bifurcation of the aorta and vena cava.
K. The reCtum filled with meconium, and tied at its upper part where the

colon was cut away.
L That branch of the inferior mefenteric artery which was going to the
colon..

M The lower branch of the fame artery, which went down into the pel-
vis behind the reCtum.
N The lower part of the bladder, that part of it which is higher than

the ofla pubis in fo young a foetus being cut away.
OO The hypogaftric or umbilical arteries cut through, where they were

turning up by the fides of the bladder in their way to the navel.
PP The ureter of each fide palling down before the pfoas mufcle and iliac
velfels, in its courfe to the lower part of the bladder.

D 2 Qg^ The

QQJFlie fpermatic arteries running a little Terpentine.

RR The teftes fituated before the pfoae mufcles, a little higher than the
inguina. In this figure the interior edge of the teftis is turned a
little outwards, to fhow the fpermatic vefiels coming forwards to
the pofterior edge of the teftis, in the duplicature of the perito-
naeum : which duplicature connects the teftis, inclofes its vefiels,
and gives it an external fmooth coat, much after the fame manner
as the duplicature of the mefentery connects the inteftine, conveys
its vefiels, and gives it a polifhed covering.

The beginning of the epididymis is feen at the upper end of the
teftis, from which it runs down on the outfide (and therefore in this
view behind the body) of the teftis.

SS The vas deferens of each fide pafiing acrofs, in a ferpentine courfe,
from the extremity of the epididymis at the outfide of the lower end
of the teftis, and then before the lower part of the ureter, in its way
to the veficula feminalis.

TT What I have called the gubernacula or ligaments of the teftes in a
foetus. On the left fide this ligament is entire, fo that it is feen
going down from the lower end of the teftis, through the ring of
the mufcle, into the fcrotum: but on the right fide its upper and
forepart is cut away, that the continuity of the epididymis and vas
deferens may be feen; and no more of the ligament is exhibited
than what is fituated within the cavity of the abdomen.

N, B. The lower part of the ligament, as it is feen in the right fide of
this figure, lies fo loofe in the paflage through the mufcles, and is
there fo loofely covered by the peritonaeum, that, when the teftis is
pulled up, more of the ligament is feen within the cavity of the ab-
domen, and then the peritonaeum is made tight and fmooth at that
place; but, on the contrary, when the fcrotum is pulled downwards
the lower part of the ligament is dragged fome way down through
the paflage in the mufcles, and the loofe peritonaeum is carried along
with it; fo that then there is a fmall elongation of that membrane,
with an orifice from the cavity of the belly, like the mouth of a
fmall hernial fac, on the forepart of the ligament.

r ax ]

PLATE II.

THE fecond figure reprefents nearly the fame parts in a foetus, fome-
what older, in order to £hew the ftate of the teftes when they

have recently defcended from the abdomen into the fcrotum. The fmall

inteftines are removed, and the large inteftines are left in their natural

lituation.

A A The liver, in out-lines.

BB The thighs, unfinifhed.

C The penis.

D The middle part of the fcrotum; on each fide of which the forepart
of the fcrotum is cut away, that the teftes may be feen.

EE The two flaps of the {kin and of the cellular membrane difledted off
from the lower part of the abdomen, and turned down upon the
thighs.

F The inteftinum coecum.

GG The appendicula coeci vermiformis.

H The arch of the colon.

I The turn-of the colon under the fpleen.

K The colon pafling down on the outfide of the left kidney.

L The laft turn of the colon, commonly called its figmoeid flexure, which
in adults is feated quite in the cavity of the pelvis.

M The beginning of the rectum.

N Part of the abdominal mufcles of the right fide, with the fmooth in-
verting peritonaeum, turned back over the fpine of the os ilium.

OO The lower part of the obliquus externus mufcle of the left fide.

P The lower part of the redtus mufcle of the right fide, turned outwards,
and towards the left fide, fo that the epigaftric artery is feen going
to the infide of that mufcle.

QJThe forepart of the bladder.

R The urachus, as it is called.

S The crural veflels coming into the thigh from behind the ligamenturn
Fallopii.

X The

T The external appearance of the fpermatic rope of the left fide.

U The external appearance of the teftis, when its tunica vaginalis, or
procefs of the peritonaeum, is a little diftended with air or water
poured into it from the cavity of the abdomen.

V The right teftis, brought fully into view by laying open the procefs of

the peritoneum in its whole length.

W The epididymis of the fame fide.

XX The fpermatic veffels.

Y The vas deferens. N. B. The peritonaeum lies before the fpermatic

veffels and vas deferens, or covers them within the abdomen ; and
its procefs or elongation covers them in the fame manner all the
way from the abdominal mufcles downwards fo that if the intef-
tine flips down after the teftis in a foetus it muft be placed before
the fpermatic veffels and vas deferens.

Z The ureter.

& The remains of the gubernaculum or ligament which bound and con-
ducted the teftis to the fcrotum.

N. B. It is evident that part of the peritonaeum, which in this figure,
is carried down in the form of a hernial fac to a little below the
teftis, lies before the teftis, epididymis, fpermatic veffels, and vas
deferens, and that it covers thofe parts in the fame manner as it
covers the abdominal vifcera, viz. the pofterior part of the fac (fup-
pofing the fac to be cut lengthways into two halves) is united with
them, and gives them a fmooth furface, while the. anterior half of
the fac lies loofe before them, and may be removed to fome diftance
from them, as when the fac is diftended with water.

PLATE III.

THE third figure reprefents the telles, &c. in the fame fubje6t ^ all
the parts above the ofla ilium being cut away, and the abdominal

mufcles and the bladder being turned downwards,

AA The thighs, unfiniftied.

B The penis.

C The middle part of the fcrotum, its lateral parts being removed to fhow
the telles.

DD The Ikin and cellular membrane of the abdomen turned down over
the thighs.

EE Part of the abdominal mufcles and peritoneum turned down at each
groin.

FF The peritonaeum covering the iliacus internus mufcle of each fide,

G The inteftinum re£tum filled with meconium.

H The bladder with the umbilical artery on each fide of it, turned a little
forwards over the fymphyfis of the pubes.

II The ureters paffing over the iliac vefiels to the pelvis.

K The right teftis expofed, as in Fig. II. V. W. XX. Y.

L The left teftis inclofed in the procefs of the peritonaeum, See Fig. II. U.

M The Tpermatic velfels of the left fide, feen through the peritoneum
which covers them, in their defcent through the abdominal mufcles
at the groin.

N The left vas deferens feen through the peritoneum, in its paftage from
the mouth of the fac to the pofterior part of the bladder.

O The mouth or aperture of the procefs of the peritoneum, whereby its
mouth or cavity communicates with the general cavity of the belly.
This aperture clofes up, and the membrane becomes fmooth at this
place, when the fœtus grows a little older ; unlefs when the gut falls
down after the teftis, and keeps it open. In that cafe it makes the
mouth of the hernial fac.

P The left epigaftric artery branching upon the infide of the réélus muf-
cle, which is here turned downwards and outwards. This artery
is always fituated, as in this figure, on the infide of the mouth of
the hernial fac, or paffage of the fpermatic velfels.

PLATE IV.

P L A T E IV.

Side view of the pelvis of a young ram, to fhow the right tefticle

remaining in the cavity of the abdomen, after the left had come
down, but which is removed with that half of the pelvis.

The tefticle which lies in the loins is flatter than common, and is only
attached by one edge, which is principally by the epididymis; there is
alfo a ligament paffing from the upper part of the common attachment
which binds the tefticle to the pofterior part of the abdominal mufcles;
this is analogous to the ligament that attaches the ovarium to the fame
part in the female quadruped.

The epididymis pafies along the outer or pofterior edge and at the
lower part becomes larger and pendulous, making a little twift upon itfelf
where it becomes vas deferens.

The vas deferens is a little contorted, and paffes down obliquely over
the pfoas mufcle to the bladder.

From the lower end of the tefticle there is a ridge continued along the
pfoas mufcle through the abdominal ring, going on to the fcrotum, which
is moft probably the gubernaculum j but it was fo much covered by a hard
fuety fat, that I could not exactly ascertain its ftrufture : at the lower
part of this ridge, about an inch and half from the ring, I found the ter-
mination of the cremafter, which was a tolerable large mufcle ; part of
its fibres feemed to arife in common with the internal oblique; while
the reft appeared to come from the pfoas and iliacus internus behind
it; the outer portion palled inwards and downwards, and fpread upon the
forepart of the ridge, or gubernaculum, where the greateft part of its
fibres were loft, and the reft of them were continued into the back part
of it. The pofterior portion got upon the iniide of the ridge and was loft
in the fame manner as the former.

A The infide of the thigh, only having the outline drawn.
JBB The iniide of the abdominal mufcles fpread out,
C The fymphyfis of the os pubis.

D The

PLATE IV.

D The mufcles of the thigh cut through at their origin where they arife

from a middle tendon.
E The lower end of the right kidney.
F G The iliac veffels expofed to {how their fituation.
H The remains of the umbilical artery.
I The urinary bladder.

K The body of the right tefticle₅ with the ramifications of the veins upon

the furface.
L The epididymis.
M The vas deferens.

N The veficulae, commonly called feminales»

OBSERVATIONS

OBSERVATIONS ON THE GLANDS SITUATED
BETWEEN THE RECTUM AND BLADDER,
CALLED VESICULiE SEMINALES.

f | ^HE bags fituated between the bladder and reftum in the male of
J. fome animals, which are commonly called veficulas feminales, have
been confidered as refervoirs for the femen, fecreted by the teft teles in the
fame manner as the gall-bladder is fuppofed to be a refervoir for the bile.
Phyfiologifts mnft have been led to this opinion from obferving that, in
the human fubjedt their dudts communicate with the vafa deferentia
before their termination in the urethra, This communication was fup-
pofed to allow the femen, when not immediately wanted, to pafs into
thefe bags from the vafa deferentia by a fpecies of regurgitation. But
more accurate obfervations refpe&ing their ftructure and contents in the
human fubjeil, and on fimilar parts in other animals fuppofed to anfwer
the fame purpofe, joined to the circumftance of their not being found in
every clafs, induced me to conclude that this opinion was erroneous»
To throw as much light upon this fubjed: as poffible, I made a number
of experiments, and availed myfelf of every opportunity which offered of
examining whatever could in any way elucidate the point 5 and from what
I have been able to colled, I think it will appear that they do not ferve
the purpofe of refervoirs of the femen.

To proceed regularly with my inveftigation, I fhall begin by compa-
ring the contents of thefe veficulae with the femen as it is emitted\'from
the penis of a living man : from which comparifon it appears that the
two fecretions are very different in their fenfible properties of colour and
fmell; and although the femen which conftitutes the firft part of the
emiffion is evidently different from the laft, yet every part of it is unlik®
the mucus found in thefe veficulas.

The femen firft difcharged from the living body is of a bluifh whit*
colour, in confiftence like cream, and fimilar to what is found in the

E 2 vafa

vafa deferentia after death: while that which follows is fomewhat like
the common mucus of the nofe, but lefs vifcid. The femen becomes
more fluid upon expofure to the air, particularly that firfl thrown out -_r
which is the very reverfe of what happens to fecretions in general. The
fmell of the femen is maukifh and unpleafant, exa&ly refembling that of
the farina of the Spanifh chefnut. The tafte is at firft infipid; yet there
is fomewhat of pungency in it, which after fome little time Simulates
and excites a degree of warmth in the mouth. The fluid contained in
thefe veficulae, in a dead body, is of a brownifh colour, and often varies
in its confidence in different parts of the bag, as if not well mixed. Its
fmell does not refemble that of the femen ; and it does not become more
fluid by being expofed to the air.

It may however be objected, that the contents of the veficulae are ge-
nerally found in a putrirl ftate, and have by that means undergone a
change in their fenfible properties. But the objection is readily obviated
by comparing this fluid with that in the vafa deferentia as it comes from
the tefticles of the fame dead body, between which there appears to be
no refemblance. To be ftill more certain of the nature of the contents of
thefe veficulae, than was pofiible from the examination of bodies which
had been dead fome time, I took an opportunity of opening a man im-
mediately after his death, who had been killed by a cannon-ball. The
fluid in the veficulae was of a lighter colour than is ufually found in men
who have been deaH a cunfiderabk, tunc, but it was not by any means
like the femen either in colour or fmell. In another man who died in-
ftantaneoufly, in confequence of falling a confiderable height, and whofe
body I infpe&ed foon after the accident, I found the contents of the
veficulae of a lightifh whey colour, having nothing of the fmell of femen_;
and in fo fluid a ftate as to run out on cutting into them.

I have likewife examined with attention a mucus which fome men
difcharge upon {training hard while at ftool, or after throwing out the
iaffc drops of urine, an adtion which requires a confiderable exertion of the
parts. This difcharge is generally called a feminal weaknefs, and is
I believe commonly fuppofed to be the femen" j but in all the cafes of
» Vide Treatife on the Venereal Difeafe, page 197,

this

this kind in which I have been confulted, it nearly refembled the con-
tents of the veficulae in the dead body perhaps not quite of fo deep a
colour. I endeavoured in vain to perfuade a gentleman who had this
complaint, that the difcharge was not feminalj till by examining his
own femen, and comparing it with that mucus, he was convinced of the
difference. This gentleman had the power of emitting the femen in the
fame quantity as ufual, immediately after the mucus had been difcharged,
which is a further proof that this fluid is not femen.^a

In this country eunuchs feldom come under our examination. We
have fometimes however opportunities of opening the bodies of thofe
who have, in confequence of difeafe or accident, loft one or both tefticles ;
and fevers! fnhjetEls of this kind I have infpe&ed after death. Perfons
who have only loft one tefticle are more to our prefent purpofe than
thofe who have been deprived of both. For it is to be prefumed that
fuch men have afterwards had connection with women, and confequently
had the action of emiffion, which muft have emptied the veficulae of the
caftrated fide, if thefe had contained femen; and as they could not be
replenished, they fhould have been found empty after death. We have
alfo in fuch cafes an opportunity of making comparative obfervations
between the veficulas of the perfect and thofe of the imperfedt fide. In
the eunuch fuch emiflions never can happen ? for the tefticks being gone,
the natural and leading ftimulus is loft ; therefore if in them the veficulas
were found full after death, it might be fuppofedto be the femen which
they had received from the tefticles before caftration, and which had
remained there ever fince. But as caftration is in fuch cafes ufually per-
formed on children, this circumftance fhould rather be confidered as a
proof that they fecrete their own mucus; yet it is probable they will
neither be fo large nor fo full in them as in the perfect man; for I am of
opinion that they are connected with generation * and that if the confti-
tution is deprived of that power, they will not grow to the full fize.
But where only one tefticle is removed, its lofs does not in the leaft affed:

^a The difcharge was truly fuppofed to be the contents of the veficulse; and it being
imagined that thofe contained femen, according to this reafoning, the difcharge muft be
feminal.

generation^

generation, therefore does not produce any change in the veficula of that
iide from which the tefticle is taken ; becaufe the veficula does not depend
upon the tefticle for its fecretion, but upon the conftitution, and the perfon
being capable of the adtion of generation,

A man who was under my care in St. George\'s Hofpital for a venereal
complaint, died there, and was difcovered to have loft his right tefticle.
From the cicatrix being hardly obfervable, it muft have been removed
fome confiderable time before his death; and the complaint for which he
was received into the hofpital is a convincing proof that he had connec-
tion with women after that period.

I infpedted the body in the prefence of Mr. Hodges, the houfe-furgeon*
and feveral of the pupils of the hofpital. Upon differing out and exa-
mining the contents of the pelvis, with the penis and fcrotum, I found
that the vas deferens of the right fide was fmaller and firmer in its tex-
ture than the other, elpecially at that end next to the abdominal rings,
near to the part that had been cut through in the operation. The cel-
lular membrane furrounding the dud: on the right fide was not fo loofe as
on the left; neither were the veftels which ramified on the right veficula
fo full of blood. But upon opening the veliculse, both appeared to be
filled with a kind of mucus limilar to that which is found in other dead
bodies ; and the veficula of the right fide was rather larger than that on
the left. Whatever therefore may be the real ufe of thefe vefieulse, we
have a proof from this difleAion, that in the human fubjedt they do not
contain the femen.

In a man who died in St. George\'s Hofpital with a very large bubono-
cele, the tefticle of that fide was difcovered to have almoft loft its natural
texture from the prefture of the hernial fac; and upon examining the
tefticle with attention, there was no appearance of vas deferens till we
came near the bladder, where it was almoft as large as ufual. The vefi-
cula of that fide was found to be as full as the other, and to contain the
fame kind of mucus.

I extirpated the left tefticle of a Frenchman on account of its being
difeafed. He was a married man, and died about a year afterwards,
having been extremely ill for feveral months before his death. On ex-
amining

amining the body, the veficulae were both found nearly full_; more efpe^
cially that of the left fide, which I fuppofe might be accidental. But
upon examining the vas deferens of the left fide, where it lies along the
fide of this bag, and where it has a fimilar ftructure with the veficulae,
I found it filled with the fame kind of mucus 3 and this I believe is
always the cafe, whether the tefticle has been removed or not.

A young man, a coachman, who had a dileafe in his left tefticle, had
it removed, at St. George\'s Hofpital, by Mr. Walker, in Auguft 1785;
and in February 1786 he returned again to the hofpital, on account of
uncommon pains all over him, and for which he requeued to be put into
the warm bath. But as he was going from the ward to the bath he
dropped down and died almoft immediately. The body was inlpedted,
with a view to difcover the caufe of bis death ; and upon an examination
of the veficulae, the bag of the left fide was as full as that on the right;
and the contents in both were exactly fimilar.

In differing a male-fubjedt, in the year 1755, for a fide view of the
contents of the pelvis, I found a bag on the left fide, lying contiguous to
the peritonaeum, juft on the fide of the pelvis where the internal iliac
veffels divide above the angle of reflection of the peritonaeum at the union
of the bladder and redhim. The left vas deferens was feen paffing on
to this bag; and what is very fingular, that of the right, or oppofite
fide, croffed the bladder near its union with the reftum to join it. I
traced the left vas deferens down to the tefticle j but on following the
right through the ring of the external oblique mufcle, I difcovered that
it terminated at once, about an inch from its paffage out of the abdomen,
in a blunt point, which was impervious. On examining the fpermatic
chord from this point to the tefticle, I could not find any vas deferens •
but by beginning at the tefticle, and tracing the epididymis from its
origin about half way along where it lies upon the body of the tefticle,
I found that it at firft became ftraight, and foon after feemed to terminate
in a point. The canal at this part was fo large as to allow of being
filled with quickfilver, which however did not pafs far, fo that a portion
of the epididymis was wanting ; and the vas deferens for nearly the whole

length

length of the fpermatic chord of the right fide.^a On the left fide the
vas deferens begun where the epididymis commonly terminates ; and there
was a deficiency of nearly an inch of the extremity of the epididymis.^b I
then differed the bag above mentioned, which proved to be the two ve~
ficulae j for by blowing air from one vas deferens, I could only inflate
half of it; and from the other vas deferens, the other half. They con-
tained the mucus commonly found in thefe bags $ but upon the rnoft
accurate examination I could difcover no dudt leading from them to the
proftate gland, nor any remains of one.

In this fubjed: it was evident that there was no communication between
the vas deferens and epididymis ; nor between thefe bags and the urethra.
The caput gallinaginis had the common appearance but there were no
orifices to be feen. The teflicles were very found, and the duds from
them to the epididymis were very manifeft and full of femen,^c

^a Vide plate I, fig. I. ^b Vide plate I, fig. 2.

^c As the femen, in confequence of this preternatural formation of parts, could not be
eonveved to the urethra in the ufual way, I conceived it poffible that there might be another
unnatural conftrucHon to make up for the deficiency in the vas deferens, and therefore exa-
mined it very carefully to fee if there were no fupernumerary vafa deferentia. I was led to
do this more particularly from often finding parts refembling them where they could anfwer
no kind of purpofe. By a fupernumerary vas deferens, I mean a fmall duct which fometimes
arifes from the epididymis, and pafles up the fpermatic chord along with the vas deferens,
and commonly terminates in a blind end, near to which it is fometimes a little enlarged. I
never found this duct go on to the urethra; but in fome inftances have feen it accompany the
vas deferens as far as the brim of the pelvis. There is no abfolute proof that this is a fuper-
numerary vas deferens ; but as we find the ducts of glands in general very iubject to Angu-
larities, and that there are frequently fupernumerary du£ts, there being often two ureters to
one kidney, fometimes diftinft from beginning to end ; at other times both arifing from one
pelvis. Thefe dufts, arifing from the epididymis, I am inclined to believe, from analogy, are
of a nature fimilar to the double ureters. They refemble the vas deferens, as being contin-
uations of fome of the tubes of the epididymis ; are convoluted where they come off from it;
and afterwards become a ftraight canal, pafling along with it for fome way, when they are
commonly obliterated.

The idea of their being for the purpofe of returning the fuperfluous femen to the circula-
tion is certainly erroneous, from their being fo feldom met with, and fo very feldom continued
further than the brim of the pelvis.

From

From thefe circumftances we have a prefumptive proof, that the femen
can be abforbed in the body of the tefticle, and in the epididymis ; and
that the veficulae fecrete a mucus which they are capable of ablbrbing
when it cannot be made ufe of. We may likewife infer from what has
been faid, that the femen is not retained in refervoirs after it is fecreted,
and kept there till it is ufed but that it is fecreted at the time in con-
fequence of certain affections of the mind Simulating the tefticles to
this action : for we find, that if lafcivious ideas are excited in the mind,
and the paroxyfm is afterwards prevented from coming on, the tefticles
become painful and fwelled from the quantity of femen fecreted and the
encreafed adtion of the veffels; which pain and fwelling is removed im-
mediately upon the paroxyfm being brought on and the femen evacuated ;
but if that does not take pi ace, the adbon of the veftels is ftill kept up,
and the pain in the tefticles will in general continue till the paroxyfm and
evacuation of the femen is brought on, which renders the adt complete;
without which a ftop cannot be put to the adtion of the veffels that pro-
duce the fecretion, nor the parts be allowed to fall back into their natural
ftate. There is at this time no fenfation of any kind felt in the feat of
the veficulae feminales. The pain in the tefticles, in confequence of being
filled with femen and the adtion being incomplete, is fometimes fo con-
fiderable as to make it neceffary to produce an evacuation of the femen to
relieve the patient.

It may be obferved, in fupport of this opinion, that thefe bags are as
full of mucus in bodies much emaciated, where the perfon has died from
a lingering difeafe, as in ftrong robuft bodies where death has happened
from violence or acute difeafes; and they are nearly as full in the old
as in the young; which moft probably would not be the cafe if they
contained femen. Thefe fads, taken from the human fubjedt, are, I
think, fufficient to eftablilh the opinion which I have laid down; but
for the fatisfadHon of others, I £hall give fuch fadts and obfervations as
have occurred in my diffeftion of other animals j. confining myfelf to
thofe which tend to clear up the point in queition.

Thefe veficulae are not fimilar either in fhape or contents in any two
genera of animals which I have diffedted 3 and they differ more in fize,

F according

according to the bulk of the animal, than any other parts whofe uies In
different animals are the fame; while the femen in moft of thofe which I
have examined may be faid to be fimilar.

The analogy which obtains between thefe bags and the gall-bladder,
in the human fubje£t, by no means holds equally good when applied to
other animals. In the horfe they are two bags like fmall urinary blad-
ders, almoft loofe and pendulous, with a partial coat from the perito-
neum, under which there are two layers of mufcular fibres ; they are
thicker in their coats at the fundus than any other part, and appear there
to be glandular. Their openings into the urethra are very large; and
although they open clofe to the vafa deferentia, do not communicate
with them. The feptum between the two dudts is not continued on
quite to the urethra, fo that they cannot, in ftrid language, be faid to
enter that paffage feparately ; but there is not length of common dudt
fufficient to admit of regurgitation from the vafa deferentia into thefe bags.
They are not -of the fame ftze in the gelding and in the ftone-horfe, being
largeft in the laft. Their contents in both are exa&ly fimilar, and nearly
equal in quantity; but in no way refembling the femen emitted by the
ftone-horfe in the coitus, or what is found in the vas deferens after death»
In the boar thefe bags are extremely large, and divided into cells of a
confiderable fize; or they may more properly be faid to form ramifications
clofely connected with one another, and having a large canal or dud
common to the whole. The Hu<£Ig contain a whiti£h fluid, very unlike
what is found in the vafa deferentia of the fame animal, with which they
have not the leaft communication.

In the rat the bags are large and flat, with ferrated edges, and lie fome
way within the abdomen, containing a thick afh coloured mucus, nearly
of the confiftence of foft cheefe, very different from what is found in the
vafa deferentia of the fame animal, with which they do not communicate,
In the beaver the bags are convoluted; their dudts have no communi-
cation with the vafa deferentia j but both the one and the other open ofi
the veru montanum.

In the Guinea-pig they are compofed of long cylindrical tubes, and lie
in the cavity of the belly ; are fmooth on their external furface, and do

not

not communicate with the vafa deferentia. They contain a thick bluifh
, tranfparent fubftance which is fofteft near the fundus, and becomes firmer
towards the openings into the urethra, where it is as folid as common
cheefe. From this circumftance, and what is obferved in the horfe, the.
fundus would appear to be the part which fecretes this fubftance, which,
is very different in colour and confidence from the contents of the vafa
deferentia, and is often found in broken pieces in the urethra-

To be more certain that the fubftance contained in thefe bags was not
the fecretion of the tefticle, I extracted one of the tefticles of a Guinea-
pig ; and fix months afterwards gave it the female. As foon as the adion
of copulation was over, (in which all the parts containing femen fhould
naturally have emptied themfelves) I killed the animal, and upon exami-
nation found the veficula of the perfe<5t fide, and that of the fide from
which the tefticle had been removed, both filled with a fubftance in every
refped: fimilar. It will fcarcely be alledged that this fubftance had been
contained in the bag before the extirpation of the tefticle; nor could it be
femen, which muft have been all thrown out in the previous connexion
with the female.

To afcertain that the contents of the veficula: are not difcharged into
the vagina of the female, with the femen in the ad: of emiffion, I killed
a female Guinea-pig as foon as the male had left her, and examined with
attention what was contained in the vagina and uterus * in neither could
I find any of the mucus of the veficulae, which from its firmnefs muft
have been eafily deteded.

In the hedge-hog thefe bags are very large, being twice the fize of
the veficula in the human fubjed.

Many animals have no fuch bags, and I believe they are wanting in
the greater part of that clafs which live chiefly upon animal food: they
are however to; be found in fome of them; and the hedge-hog is an
example. There is no apparent difference in the tefticles, vafa deferen-
tia, or femen of the animals which have veficulae and of thofe which
have none j and the. mode of copulation, as far as thefe bags can be con-
cerned, is very fimilar in both.

In

In birds, as .far as I have yet obferved, there is nothing analogous to
thefe bags ; and yet there appears to be no difference between the mode
of copulation of the drake and the bull, or ram ; and it is natural to
fuppofe that if the veficulae were refervoirs of femen, they would be more
neceffary in birds; the power of repeating the ad; of copulation being in
them infinitely greater than in quadrupeds : and indeed we find that in
birds there are refervoirs which will account for this power the vafa
deferentia being enlarged jufl before they open into the redum, probably
to anfwer that intention. As birds have no urethra, but fimply a groove,
as the drake and gander; and many are even without a groove, as the
common fowl, it was abfolutely neceffary there fhould be fuch a refervoir
fomewhere.

What I have obferved of the refervoir of birds is equally applicable to
amphibious animals and that order of fifh called rays.

From the above obfervations I think we may fairly conclude that thele
veficulas are not for the purpofe of containing femen ; the fingle circum-
fiance of their duds being united to thofe of the teflicles in the human
fubjed not appearing fufficient to fet afide the many fads which are con-
tradidory to fuch an opinion.

Having endeavoured to fhow that the ufe of thefe veficulas has hitherto
been mifunderftood, the following obfervations will tend to prove that
they are fubfervient to generation, though their particular ufe is not yet
difcovered -₃ and for ihe better underftanding this part of the fubjed I
fhall premife the following fads.

Animals have their natural feelings raifed or increafed in proportion as
the parts conneded with fuch feelings are formed, and are in a flate to
ad j and the difpofition for adion in thefe parts is alfo in proportion to
their formation and the excitement of fuch feelings. But that thefe feel-
ings may be duly excited, it is neceffary that the animal and the parts
Ihould be healthy, in good condition, and in a certain degree of heat
fuitable to that clafs to which the animal belongs. As in moft parts of
the globe the feafons vary in their temperature 5 the cold in fome of
them is fo confiderable as to prevent thofe feelings or difpofitions in
animals from taking place; and in many fituations the general influence

of

of the cold upon them is fo great, as during its continuance to deprive
them of thefe feelings and difpofitions, and to render them, for the time,
unfit for the purpofes of generation/

The tefticle becomes at this feafon fmall, a fadt very obvious in birds,
of which the fparrow may be produced as a proof: for if a cock-fparrow.
is killed in the winter, before the days have begun to lengthen, the tefti-
cle will be found very finally but if that organ is examined at different
times in other fparrows, as the warmth of the weather increafes, and if
this examination is continued to the breeding feafon, the difference in
the fize of the tefticle will be very ftriking.^c This circumftance is not
peculiar to birds, but is common, as far as I yet know, to all animals
which have their fcafons of copulation. In the buck we find the tefticles
are reduced to a very fmall fize in the winter; but in the land-moufe,
mole, &c. this diminution is ftill more remarkable. Thofe animals,
on the contrary, who are not in a ftate of nature, have no fuch change
take place in their tefticles; and from not being much affected by feafons
are confequently always in good condition, and in that ftate to which
other animals that are left to themfelves can only attain in the warmer
feafon. Therefore in man, who is in the ftate we have defcribed, the
tefticles are nearly of the fame fize in winter as in fummer : and nearly,
though not exactly, the fame thing may be obferved in the horfe, ram,
&c. thefe animals having their feafons in a given degree.

The variation above taken notice of is not confined to the tefticles, but
alfo extends to the parts which are connected with them. For in thofe
animals that have their feafons for propagation, the moft diftindtly marked,
as the land-moufe, mole, &c. the veficulas are hardly difcernible in the
winter; and in the fpring are very large, varying in fize in a manner
fimilar to the tefticle. It may however be alledged, that the change in
thefe bags might naturally be fuppofed to take place, admitting them
to be feminal refervoirs : but what happens to the proftate gland, which

^a It is not required that the feafon for the copulation of different animals fhould be equally
warm ; for the frog copulates in very cold weather, while the fnake and lizard, which are
alfo cold, fleeping animals, do not copulate till the feafon is warm.

* Vide plate IILfig. 1, ^c Vide plate III.fig. 5. :

has

has never been fuppofed to contain femen, will take off the force of this
objection ; fince in all the animals which have fuch a gland (and which
have their feafon for propagation) it undergoes a fimilar change. In
the mole the proftate gland in winter is hardly obfervable, but in the
fpring becomes very large and is filled with mucus.

From thefe obfervations it is reafonable to infer that the ufe of the veficu-
las in the animal ceconomy, muft in common, with many other parts, de-
pend upon the tefticles. For the penis, urethra, and all the parts connected
with them are fo far fubfervient to the tefticles, that I am perfuaded few
of them would have exifted if there had been no tefticles in the original
conftrudtion of the body -_y and thefe would have been fo formed as merely
to affift in the expulfion of the urine. To illuftrate this opinion let us
obferve what is the difference between thefe parts in the perfect male,
and in a male that hue heen deprived of the tefticles when very young, at
an age in which they have had no fuch influence upon the animal ceco-
nomy as to effedt the growth of the other parts. In the perfect male the
penis is large; the corpora cavernofa* being capable of dilatation.. The
corpus fpongiofum is very vafcular^bj and that part of the canal which
is called the bulb is confiderably enlarged, forming a cavity; the muf-
culi acceleratores urine, as they are termed, are ftrong and healthy. In
many animals which have long penifes, they are continued forwards
to the end of it; and in others they are not extended fo far, but are very
large.

On the contrary, in the caftrated animal the penis is fmall and not
capable of much dilatation _; the corpus fpongiofum is lefs vafcular; the
cavity at the bulb is little larger than the canal of the urethra y and the

^a The cells of the corpora cavernofa are mufcular, although no fuch appearance is to be
obferved in men: for the penis in ere&ion is not at all times equally diftended: the penis in
a cold day is not fo large in erection as in a warm one; which probably arifes from a kind of
fpafm that could not act upon it if it were not mufcular. .

In the horfe, the parts compofing the cells of the penis appear evidently mufcular to the eye %
and in a horfe juft killed, they contrail upon being ftimulated.

■ ^k It may not be improper to obferve that the corpus fpongiofum urethrae, and glans penis,
are not fpongy or cellular, but made up of a plexus of veins. This ftru£ture is difcernible in
the human fubjeft; but much more diftmctly feen in many animals, as the horfe, &c.

mufcles

mufcles are white, fmall, and have a ligamentous appearance. The fame
obfervations are true if applied to the eredtores penis.

The penis of the perfedt male is of a fufficient length, when eredted,
to reach to the further end of the vagina of the female. In the caftrated
animal it is much fhorter; and eredtions having then become unneceffary,
the parts which fhould projedt, often adhere to the in fide of the prepuce.
The eredfcores mufcles in the perfedt male are ftrong enough to fqueeze at
once the blood out of the crura into the body of the penis, fo as to
ftraiten and contradt the urethra inftantaneoufly, and the acceleratores
urinae¹ have fufficient power to throw out the femen that is gradually ac-
cumulated at the bulb for ejedtion.

The proftate gland^b, Cowper\'s glands, and the glands along the urethra,
(of which the lacunae are the excretory dudts) in the perfedt male are large
and pulpy, fecreting a confiderable quantity of a flimy mucus, which is
fait to the tafte, is moft probably for the purpofe of lubricating thofe
parts, and is only thrown out when in vigour for copulation : while in
the caftrated animal they are fmall, flabby, tough and ligamentous, and
have little fecretion. From this account a confiderable difference in ap-
pearance is diftinguifhable between the parts connedted with generation of
the perfedt male, and thofe which remain in one that has been caftrated;

1  I fhall call thefe mufcles, expulfores feminis, as I apprehend their real ufe to be for the
expulfion of that fecretion: thefe mufcles likewife throw out thofe drops of urine which are
collected in the bulb from the laft contractions of the bladder; and they have been from this
circumftance named, acceleratores urinae ; but if a receptacle had not been neceflary for the
femen, thofe mufcles had probably never exifted, and the laft drops of urine would have been
thrown out by the action of the bladder and urethra, as in feme meafure is the cafe in the
caftrated animal. That the urethra has the power of contraction is evident upon the applica-
tion of any ftimulus ; for I have feen the urethra refufe to allow an injection to pafs on ; and
in that part where the injection flopped, a fulnefs was felt which terminated at once : this
contradlion is moft probably in the internal membrane.

^k The proftate gland is not common to all animals. It is wanting in the bull, buck, and
moft probably I believe in all ruminating animals. In this clafs the coats of the veficulse are
much thicker, and more glandular, than in thofe who have proftate glands; it is therefore
natural to fuppofe that the veficulae anfwer nearly the fame purpofes as the proftate gland.

The proftate gland, and Cowper\'s glands, as well as the veficulae, are wanting in birds,
in the amphibious animals, and in thofe fifh which have tefticles, as all of the ray kind.

more

PLATE I.

SHOWS two tefticles with the fpermatic chords dilTeded; in the one
the vas deferens, in the other a portion of the epididymis, is wanting.

Fig. i. The right tefticle and fpermatic chord.
AA The body of the tefticle.

BB The fpermatic chord in which there is no appearance of vas deferens.
C The epididymis, where it takes its origin from the body of the tefticle.
D The abrupt termination of the epididymis, it not being continued
to the lower end of the tefticle.

Fig. 2. The left tefticle.
AA The hody of the tcfticle.

B The blood-veflels of the tefticle feparated from the vas deferens.
C The origin of the epididymis.

D The termination of the epididymis j to fhow which the tunica vagi-

nales is removed.
E The origin of the vas deferens.

F The vas deferens, as it paftes up towards the ring of the abdominal
mufcles.

p. 42 .

^laCeZ.

THE nine following papers Have been read at the Royal
Society, and publifhed in the Philofophical Tranfac-
tions; but in a work of fo general a nature, and of
which physiological inquiries make fo fmall a part, the
few fa&s and obfervations which I have given upon fuch
fubjects may probably be overlooked by thofe who are
not members of that fociety. That they may be more
eafily procured by ftudents in medicine, and other
readers, I have, by an application to the President and
Council of the Royal Society, obtained leave to reprint
fuch of them as I confider to be connected with the
principles and a&ions of the animal ceconomy ; and
I have added fuch obfervations and remarks as have oc-
curred to me fince the time they were read before the
Royal Society,

ACCOUNT

r 43 ]

THE EXPLANATION Op

PLATE II.

Side view of the pelvis, taken from the fame fubje6t as plate I, in

which the vafa deferentia did not communicate with the veficula?;,

and the veficulae did not communicate with the urethra.

A The body of the penis.
B The fymphyfis of the pubis.
C The bladder.
D The left ureter,
E E The redtum,
F The anus.

G The fphinder mufcle of the anus, turnad afide.
H The levator mufcle of the anus, turned down.
I The proftate gland.
K The Cowper\'s gland of the left-fide.
L The peritoneum, which lined the left fide of the pelvis.
M The facrum, where it is articulated with the os ileum.
N The left vas deferens.
O The veliculae.

Tlafrill.

1 Jan

2 .Middle of February

3 . Begï rm tngofrch

Zatte rend of March

ACCOUNT OF THE FREE MARTIN.

GENERATION, when produced from a feed, has two caufes-
which concur towards its perfection; the one which forms the
feed, the other which gives it the principle of action.³

The caufe which forms the feed is called the female, the other caufe
is called the male; but thofe two caufes in general make only a part of
a whole animal, or are rather parts fuperadded to an animal. Probably
they were firft confidered in animals where thofe parts were feparated, or
in which the female parts were found complete in one animal and the
male in the other ; therefore the terms female and male have been applied
to the whole animal, dividing them into two diftindt fexes, and the
parts which formed either the one fex or the other were called- either
the female or the male parts of generation 5 but upon a more perfect
knowledge of animals, and of thofe parts, they were found in many of
the inferior tribes to be united in the fame animal, which,, from poUeff-
ing both parts, has got the name of hermaphrodite.

As both male and female parts are natural to moft animals* as the
union of them in the fame animal is alfo natural to many, and as the
feparation of them in diftindt animals is only a circumftance making no

¹ It may be necefiary for fome of my readers to- have explained to. them what I mean by a
feed.. I: do fuppofe that the word feed was firft applied to grain, or that which is always
called feed in the vegetable; which feed is the part of that clafs of vegetables in which the
matter of the young vegetable exifts, or is formed; The principle of arrangement in the
farina, or male part,, fitting the feed for action, being at firft not known, a falfe analogy
between the vegetable and animal was eftablifhed, and the. matter, fecreted by the teftes
was called the feed : but from the knowledge of the diftindt fexes in the vegetable, it is
well: known th?vt the feed is the female production in them, and that the principle of arrange-
ment for action is from the male. The fame operation and principles takes place in many
orders of animals, viz. the female produces a feed in which is the matter fitted for the firft
arrangement of " the organs of the animal, and which receives the principle of- arrangement
fitting them for action from the male,.

effentia.1

effential difference in the parts themfelves, it becomes no great effort or
uncommon play in nature to unite them in thofe animals in which they
are commonly feparated.

And accordingly we find many of thofe orders of animals, which natu-
rally have them feparate, have them fometimes united.

From this account hermaphrodites may be divined into two kinds, the
natural and the unnatural.

The natural hermaphrodite belongs to the inferior and more limple
genera of animals, of which there are a much greater number than of
the more perfect but as animals become more complicated, have more
parts, and each part is more confined to its particular ufe, a feparation of
the two neceffary powers for generation have alfo taken place.

The unnatural hermaphrodite, I believe, now and then occurs in
every tribe of animals having diftinft fexes, and is to be met with in all its
gradations, from the diftinft fex to the complete union of the male and
female organs, but is more common in fome than in others." I fancy it
is moft rarely to be met with in the human fpecies, never having feen
an inftance. I can fay the fame of dogs and cats, with which lafl
however I am lefs acquainted; but in the horfe, afs, fheep, and black
cattle, it is very frequent.

There is one part common to both the male and female organs of
generation in all animals which have the fexes diftind:; in the one fex
it is called the penis, in the other the clitoris; its fpecific ufe in both is
to continue, by its fenfibility, the action excited in coition till the pa-
roxyfm alters the fenfation. In the female it probably anfwers no other
purpofe; but in the male it is more complicated to adapt it for the
purpofe of expelling and conducting the femen that has been fecreted in
confequence of the a&ions fo excited.

Though the unnatural hermaphrodite be a mixture of both fexes, and
may poffefs the parts peculiar to each in perfection, yet it can not poflefs
in perfection that part which is common to both. For as this common

^a Quere: Is there ever in the genera of animals, that are natural hermaphrodites, a repa-
ration of the two parts forming diftinct fexes ? If there is, it may account for the diftin&ion of
fexes ever having happened.

part

part is different in one fex from what it is in the other, and it is impoflible
for one animal to have both a penis and clitoris; the part which they have
mult of courfe partake of both fexes, and confequentlv render the herma-
phrodite fo far imperfect But thofe parts which are peculiar to each fex,
may be perfectly joined in the fame animal, which will come up to
the idea of the trueft hermaphrodite; although it may not be necefiary
that the parts peculiar to the one fex fhould be blended with thofe of the
other, in the fame way that the penis is with the clitoris ; yet this fome-
times happens in parts whofe ufes are equally fimilar, as the tefticle and
ovarium, forming one body with the properties of neither; which as it
approaches nearer to the tefticle or ovarium, will make the animal partake
more of the one fex than the other; and fome of them, from the famenefs
of their fituation in the two fexes, in many animals may interfere with one
another.

The parts in the female appropriated for the purpofe of fupplying the
young with nourilhment are varioufly placed in different animals. In the
horfe, black cattle, fheep, and other granivorous animals, their fituation
is between the hind legs, which is alfo the place allotted for the tefticles
of the male of this tribe; (and probably of all thofe in which they come
out of the cavity of the belly) therefore in the hermaphrodite which has
both thefe parts, the tefticles are in fome degree obliged to come down
into the udder, which does not receive them fo readily as the fcrotum.

The hermaphrodites, which I have feen, have always appeared externally,,
and, at firft view, to be females : this arifes from the penis being the part
principally deficient, and there being an opening behind like the bearing
in the female; and as the tefticles in fuch hermaphrodites feldom come
down, the udder is left to occupy its proper place. In thofe animals
where the female is preferved for breeding only, as in fheep, goats, pigs,.
6cc. they are generally kept, from their being fuppofed to be females.

Among horfes they are very frequent:. I have feen feveral, but never
diffedled any. The moft complete was one in which the tefticles had:
come down out of the abdomen into the place where the udder fhould.
have been,, (viz. more forward than the fcrotum) and had the appearance
©f an. udder, not being fo pendulous as the fcrotum in the perfect male of

fuch

fuck animals. There were alfo two nipples, of which the male have no
perfect form, being blended in them with the fheath or prepuce, of which
there was none here. The external female parts were exactly fimilar to
thofe of the perfect female ; but inftead of a common-fized clitoris, there
was one about five or fix inches long, which, when ereft, Hood almoft
directly backwards.

I procured a foal afs, very fimilar in external appearance to the horfe,
and killed it, to examine the parts. It had two nipples, but the tefticles
were not come down as in the above; owing perhaps to the animal\'s
being yet too young.

There was no penis palling round the pubis to the belly as in the per-
fect male afs.

The external female parts were fimilar to thofe of the fhe-afs. Within
the entrance of the vagina was placed the clitoris, but much longer than
that of a true female, its length being about five inches. The vagina
was pervious a little further than the opening of the urethra into it, and
there it was obliterated 3 from thence up to the fundus of the uterus
there was no canal. The common uterus was hollow at the fundus,
or had a cavity in it, and then divided into two horns, which were alfo
pervious. Beyond the termination of the two horns were placed the
ovaria as in the true female, but I could not find the Fallopian tubes.
From the broad ligaments to the edges of which the horns of the uterus
and ovaria were attached, there palled towards each groin a part fimilar
to the round ligament in the female, which were continued into the
rings of the abdominal mufcles ; but with this difference, that there was
continued with them a procefs or theca of the peritoneum, fimilar to the
tunica vaginalis communis in the male afs, and in thele thecae were found
the tefticles; but I could not obferve any vafa deferentia pafiing from
them.

Here then were found in the fame animal the parts peculiar to each fex
(although very imperfect) and that part which is common to both, but
different in each, was a kind of medium of that difference.

Something fimilar to the above I have feen in fheep, goats, &c. but I
ihall not at prefent trouble the reader with a defcription of hermaphro-
dites

OF THE FREE MARTIN. ₄₉

dites in general, as it is a very extenfive fubjeCt, admitting of great variety,
which would make them appear a production of chance, whereas the
intention of this account is to point out a circumftance which takes place
in the production of hermaphrodites in black cattle, which appears
to be almoft an eftablifhed principle in the oeconomy of propagation of
that fpecies of animal, and perhaps peculiar to them.

It is a fad: known, and I believe almoft univerfally underftood, that
when a cow brings forth two calves, and one of them a bull-calf, and
the other to appearance a cow, that the cow-calf is unfit for propagation;
but the bull-calf becomes a very proper bull. This cow-calf is called in
this Country a free martin ; and is juft as well known among the farmers
as either cow or bull. Although it will appear from the defcription of
this animal, that it is an hermaphrodite, being in no refpeCt different
from other hermaphrodites, yet I fhall retain the term free martin, to
diftinguifh the hermaphrodite produced in this way, from thofe which
refemblc the hermaphrodite of other animals : for I have reafon to believe
that in black cattle, fuch a deviation may be produced without the cir-
cumftance of twins ana even¹ when there are twins, the one a male the
other a female, they may both have the organs of generation perfectly
formed. But when I fpeak of thofe which are not twins, I fhall call them
hermaphrodites j the only circumftance worth our notice being a Angu-
larity in the mode of production of the free martin, and its being, as far
as I yet know, peculiar to black cattle.

This calf has all the external marks of a cow-calf fimilar to what was
mentioned in the unnatural hermaphrodite, viz. the teats and the external
female parts, called\'by farmers the bearing.

When they are prelerved it is not for propagation, but for all the pur-
pofes of an ox or ipayed heifer, viz. to yoke with the oxen, and to fatten
for the table.^a

They are known not to breed : they do not fhow the leaft inclination
for the bull, nor does the bull ever take the leaft notice of them.^h

i -
³ I need hardly ohferve here, that if a cow has twins, and they are both bull-calves, that
they are in every refpect perfect bulls; or if they are both cow-calves, they are perfect cows.
^h Vide Lellie on Hufbandry, p. 98, 99.

H They

They very much referable in form the ox or fpayed heifer, being con-
fiderably larger than either the bull or the cow, the horns being very
fimilar to the horns of an ox.

The bellow of the free martin is fimilar to that of an ox, having more
refemblance to that of the cow than of the bull. Free martins are very
fufceptible of growing fat with good food. The flefh, like that of the
px or fpayed heifer, is in common much finer in the fibre than either the
bull or cow; and is fuppofed to exceed that of the ox and heifer in delicacy
of flavour, and bears a higher price at market,

However, it feems that this is not univerfal; for I was lately informed
by Charles Palmer, Elq. of Luckley in Berkfhire, that there was a free
martin killed in his neighbourhood, and from the general idea of its being
better meat than common, every neighbour befpoke a piece, which
turned out nearly as bad as bull-beef, at leaft v/orfe than that of a cow.
It is probable that circumftance might arife from this animal having more
the properties of the bull than the cow, as we fhall fee hereafter that
they are fometimes more the one than the other.^a Although what I have
faid with relpeCt to the productions of free martins is in general true, yet
I was lately furnifhed with an inftance, by the afliftance of Benjamin
Way, Efq. of Denham, near Uxbridge, who knew that I was anxious
to afcertain this point, that it does not invariably hold good.

One of his cows having produced twins, which were to appearance
male and female, upon a fuppofition that the cow-calf was a free martin,
he obligingly offered either to give it me, or to keep it till it grew up,
that we might determine the faCt: as I conceived it to be a free martin,
and was to have the liberty of examining it after death, I defired that he
would keep it; but unfortunately it died about a month old. Upon
examining the organs of generation, they appeared to be thofe of the

^a The Romans called the bull taurus : they however talked of taurse in the feminine gender.
And Stephen obferves, that it was thought the Romans meant by taurae, barren cows, and
called them by this name becaufe they did not conceive. He alfo quotes a paflage from Co-
lumella, lib. vi. cap. 22. " and like the taurse, which occupy the place of fertile cows, fhould
be reje£ted, or fent away." He likewife quotes Varro, De re Ruftica, lib. ii. cap. 5. " The
cow which is barren, is called taura." From which we may reafonably conjecture that the
Romans had not the idea of the circumftances of their production.

female,,

female, and perfectly formed; but to make this more certain, I procured
thofe parts of a common cow-calf, and compared them together, and
found them exa&ly alike. This made us regret that the animal had not
lived long enough for us to fee if it would breed ; for. the conftrudtion of
the parts being to appearance perfect, is not fufficient of itfelf to ftamp it
a true or perfedt female ; for I can fuppofe that the parts being perfectly
formed, but without the power of propagation, may conftitute the moft
limple kind of hermaphrodite. It is however moft probable that this was.
a perfect female, which is an exception to the common rule; and if there
are fuch deviations as twins being perfedt male and female, why not fup-
pofe, on the other hand, that an hermaphrodite may be produced fingly,
as in other animals ; and I am the more inclined to this opinion, from
finding a number of hermaphrodites among black cattle, without the cir-
cumstances of their birth being afcertained.

Hermaphrodites are to be met with in (heep; but from the account
given of them, I Ihould fuppofe that they are not free martins. I have
feen feveral of them which appeared to be imperfect males, having the
penis terminating in the perinaeum ; the orifice of which appeared like
the bearing in the female. They are not naturally ftimulated to put
themfelves in the pofition of the female when they void their water, fo
that when they pafs it they wet all the furrounding parts, which being
covered with wool, retains the urine, keeps them continually wet, and
gives them a ftrong fmell. They are mentioned as both male and female-,
which is not reconcileable to the account given of the free martin .

I believe it had never been even conjectured, notwithftanding all thofe
peculiarities, what was the true nature of the free martin.

From the Angularity of the animal, and the account of its production,
I was almoft ready to fuppofe the whole a vulgar error; yet from the
univerfality of the teftimony in its favour, it appeared to have fome foun-
dation ; and therefore I eagerly fought for an opportunity to fee and examine,
one. Since when I have fucceeded in this inquiry, and have feen feveral;
the firft of which was one belonging to John Arbu thnot, Efq. of Mitcham,
which was calved in his own farm. He was fo obliging as to allow me
to fatisfy myfelf, by permitting me firft to have a drawing made of the

H 2 animal

animal while alive, which was executed by Mr. Gilpin ; and after death
to examine the parts. When the drawing was made of Mr. Arbuthnot\'s
free martin, John Wells, Efq. of Bickley Farm, near Bromley in Kent,
was prefent, and informed us, that a cow of his had calved two calves,
one of which was a bull-calf and the other a cow-calf. I defired Mr.
Arbuthnot to fpeak to Mr. Wells to keep them, or let me buy them of
him ; but from his great defire for natural knowledge he very readily
preferved both till the bull ihewed all the figns of a good bull; and when
the free martin was killed he allowed me to infped the parts.

Of all the free martins which I have differed, I fhall only give the
defcriptions of three, which point out mofl diftin&ly the complete free
martin, with the gradations towards the male and female.

THE DESCRIPTION OF THE THREE FREE MARTINS\'.

Mr. Arbuthnot\'s free martin.⁵¹

i

The external parts were rather fmaller than in the cow. The vagina
palfed on, as in the cow, to the opening of the urethra, and then it
began to contract into a fmall canal, which paffed on to the divifion
of the uterus into the two horns, each horn paffed along the edge of the
broad ligament laterally towards the ovaria.

At the termination of thofe horns were placed both the ovaria and the
tefticles; both were nearly of the fame iize, which was about as large a$
a fmall nutmeg.

To the ovaria I could not find any Fallopian tube.

To the tefticles were vafa deferentia, but they were imperfect. The
left one did not come near the tefticle; the right only came clofe to it,
but did not terminate in a body called the epididymis. They were both
pervious, and opened into the vagina near the opening of the urethra.

^a This animal was feven years old, had been often yoked with the oxen; at other times
went with the cows and bull, but never (hewed any defires for either the one or the other.

On the pofterior furface of the bladder, or between the uterus and
bladder, were the two bags called veficulas feminales in the male, but-
much fmaller than what they are in the bull : the duds opened along
with the vafa deferentia. This was more deferving the name of herma-
phrodite than the two following ; for it had a mixture of all the parts,
although all were imperfed.

Mr. Wright\'s free martin, five years old.

This animal had more the appearance and general charader of the
ox, or fpayed heifer, than either the bull or cow. The vagina termi-
nated in a blind end, a little way beyond the opening of the urethra,
from which the vagina and uterus were impervious. The uterus at its
extreme part divided into two horns. At the termination of the horns were
placed the tefticles inftead of the ovaria, as is the cafe in the female. The
reafons why I call thofe bodies tefticles, are the following. Fir ft, they
were more than twenty times larger than the ovaria of the cow, and nearly
the fize of the tefticles of the bull, particularly thofe of the ridgill, or
bull whofe tefticles never come down. Secondly, the fpermatic. arteries
were fimilar to thofe of the bull, efpecially of the ridgill. Thirdly, the
cremafter mufcle paffed up from the rings of the abdominal mufcles to
the tefticles, as it does in the ridgill/

There were the two bags placed behind the bladder, "between it and
the uterus. Their duds opened into the vagina, a very little way beyond
the opening of the urethra but there was nothing fimilar to the vafa
deferentia.

As the external parts had more of the cow than the bull, the clitoris,
which may be reckoned an external part, was alfo fimilar to that of the

^a Although I call thefe bodies tefticles for the reafon given, yet they were only imitations
of fuch j for when cut into they had nothing of the ftruiture of the tefticle : not being fimilar
to any thing in nature, they had more the appearance of d-feafe. From the feeming imperfec-
tion of the animal itfelf, it was not to be fuppofed that they fhould be "tefticles, for then the
animal fhould have partaken of the bull, which it certainly did not,

cow;

cow not at all in a middle ftate between the penis of the bull and the
clitoris of the cow, as I have defcribed in the hermaphrodite horfe. There
were four teats; the glandular part of the udder was but fmall.

This animal cannot be faid to have been a mixture of all the parts of
both fexes, for the clitoris had nothing fimilar to the penis in the male,
and was different in the cow part, in having nothing fimilar to the ovaria ;
nor was the uterus a cavity.

Mr. Well\'s free martin.

This animal was never feen to fhow any figns of a defire for the
male, although it went conftantly with one. It looked more like an
heifer than what they commonly do; but as it was only between three
and four years old when killed, it is very probable that it was not fuffi-
ciently old to have taken the characters of the ox ; however this may be
owing to another circumftance that will be mentioned hereafter.

The teats and udder were fmall compared with thofe of an heifer,
but rather larger than in either of the former; the beginning of the
vagina was fimilar to that of the cow, but foon obliterated beyond the
opening of the urethra, as in the laft defcribed. The vagina and uterus
to external appearance was continued, although not pervious j and the
uterine part divided into two horns, at the end of which were the ovaria.

I could not obferve in this any other body which I could fuppofe to
be the tefticle.

There was on the fide of the uterus an interrupted vas deferens broken
off in feveral places.

Behind the bladder, or between it and the vagina, were the bags called
veficulse feminales; between which were the terminations of the two vafa
deferentia.

The dudts of the bags and the vafa deferentia opened as in the former.

This could not be called an exadt mixture of all the parts of both fexes,
for here was no appearance of tefticles.

The

The female parts were imperfect, and there was the addition of part
of the vafa deferentia, and the bags called veficulae feminales.

This circumftance of having no tefticles, perhaps was the reafon why
it had more the external appearance of an heifer than what they com-
monly have, and more than either of the two former,

HIS plate fliows the organs of generation of Mr. Arbuthnot\'s free

martin, which are almoft a complete mixture of the male and
female; with this ftrudiure of the parts the external appearances and ge-
neral character of the animal correfponded, it being neither that of the
bull nor cow, but a mixt character.

A The peak of the labia.
B B The two labia.
C The glans clitoridis.
D D The infide of the common vagina,
E E Orifices of the dudts of two glands.
F The orifice of the meatus urinarius.
G G The true vagina.

H H Either the contracted vagina, or what may be called uterus,
I I The horns of ditto, only pervious a little way.
K The right ovarium deprived of its capfula.
L The left ovarium inclofed in its capfula.
M A b riffle introduced through the orifice into the capfula,
N The right tefticle.
OOOO The right vas deferens.
P P The veficulae feminales.

QQJThe duds of veficulae feminales feen through the vagina.
R Points to the openings of the vafa deferentia and veficulae feminales.

PLATE

THIS plate reprefents the organs of generation of Mr. Wright\'s free
martin, which are more the parts of a bull than thofe of a cow ;
and the animal while alive had a good deal the character and look of an
ox.

A The peak of the labia.
B B The labia.
C The glans clitoridis.

D D D D The inner furface of the common vagina.
E E The orifices of the dudts of two glands
F Meatus urinarius.

G G The inner furface of the true vagina, terminating in a blind end
at H.

H The termination of the vagina in a blind end.
1111 What may be called uterus, but impervious.
KK What may be called horns of the uterus.
L L The tefticles.
M M The fpermatic veffels.
N N The cremafter mufcles.
O O The veliculas feminales.

P P The dudts of the veficulae feminales feen through the vagina.
Q^Points to the dudts of ditto, into which are introduced briftles,

c 6x ]

THIS plate exhibits a front view of the organs of generation of Mr.
Wells\'s free martin, which are more the parts of a cow than of a
bull, and the animal itfelf refembled a young heifer very much in its
appearance.

A The clitoris.
b b The crura clitoridis.
c The urethra.
D The bladder.

E The body of the uterus beyond the bladder, which is impervious,
F F Thé horns of ditto, which are alfo impervious.
G The left ovarium deprived of its capfula.
H The right capfula incloiing its ovarium.
1111 Interrupted parts of the vafa deferentia.
K K The fpermatic veflels.
L The gubernaculum of the right lide.

M The beginning of the tunica vaginalis communis, into which is in-
troduced a brittle to {how that it is hollow.
n -n veffels going behind the bladder,
O O The two ureters.
p p The veficulae feminales.

account

.Ft (fir.

ACCOUNT OF AN EXTRAORDINARY

PHEASANT.

EVERY deviation from that original form and ftrudture which gives
the diflinguifhing character to the productions of nature, may not
improperly be called monftrous. According to this acceptation of the
term, the variety of monfters will be found to be infinite. As far as my
knowledge has extended, there is not a fpecies of animals, nay there is
not a fingle part of an animal body which is not fubjed: to extraordinary
formation. Nor does this appear to be a matter of mere chance ; for it
may be obferved, that every one has a difpofition to deviate from nature
in a manner peculiar to itfelf. It is likewife worthy of remark, that
each Species of animals is difpofed to have fupernumerary parts of the
fame kinds, and nearly the fame fort of defe&s; but every part is not
perhaps fubjedt to a great variety of forms, each part of each fpecies
having its monftrous form, as it were, originally imprefled on it by the
hand of nature.

It is well known, that there are many orders of animals which have
the two parts defigned for the purpofe of generation different in the fame
fpecies, by which they are diftinguifhed into male and female: but this
is not the only mark of diftindtion in many genera of animals in the
greateft part the male being diftinguifhed from the female by various
marks. The differences which are found in the parts of generation them-
felves, I fhall call the fir ft, or principle; and all others depending upon
thefe I fhall call fecondary. The firft belong equally to both; but the
fecondary will be found principally, although not entirely, in the male.

One of the moft general marks is the fuperior ftrength of make in
the male; and another circumftance, perhaps equally fo, is this ftrength
being directed to One part more than to another, which part is that moft
immediately employed in fighting. This difference in external form is
more particularly ftriking in the animals whofe females are of a peaceable

nature;

nature j fuch are the greateft number of thofe which feed onvegetables, and
the marks to difcriminate the fexes are in them very numerous. As the
males of almoft every clafs of animals are probably difpofed to fight, they
are, as I have obferved, ftronger than the females. In many there are
parts folely deftined for that purpofe, as the fpurs in the cock, and the
horns in the bull; on which account the strength of the bull lies prin-
cipally in his neck, that of the cock in his limbs.

In carnivorous animals, whofe prey is often of a kind which it requires
ftrength to kill, we do not find fuch a difference in the form of the male
and female ; very little being difcernable in that of the dog and bitch -_y
in the he or fhe cat ; or in the cock and hen of the eagle 5 a difference
however is often perceivable in the whole or in fome part of their exter-
nal covering ; the mane of the lion, for inftance, diftinguifhing him from
the lionefs : and the males of fuch animals as neither fight nor feed on
flefh, are diflinguifhable from the female merely by fome peculiarity in
the covering of their bodies, as the cock and hen in many birds. The
male of the human fpecies is difKngui£hcd from the female, both by his
general ftrength and his covering, as alfo by a difference of voice.

In thofe orders of animals where the fexes are diftindt, we may not only
obferve the genital organs to be fubje£t to a mal-conformation, fimilar to
a mal-conformation in any other part of the animal; but that an attempt
is fometimes made to unite the two parts in one animal body, producing
an animal called an unnatural hermaphrodite.

It is my intention at prefent to extend my inquiry on this fubied; no
further than to what relates to the refemblance which one fex bears to
another in thofe diftinguifhing properties which I term fecondary.

The unnatural hermaphrodites appear to be governed by the fame cer-
tain laws by which fuch extraordinary formation of parts is effected ; for
it is obfervable, that thefe deviations obtain through a whole fpecies of
animals precifely in the fame manner. I have already given an account
of the .free martin, which exhibits a mixture of the two parts of genera-
tion in the fame animal.

We find however, that there is often a change of the fecondary pro-
perties of one fex into thofe of another -₃ the female in fuch refpe&s now

and

and then aftuming the peculiarities of the male; and it may be obferved,
that fome claffes are more liable than others to this change _} a fmgular
example of which is to be the fubjedt of the following pages.

I here beg leave to premife, that in animals juft born, or very young,
there are no peculiarities of fhape to diftinguifh one fex from the other,
exclufive of what relates to the organs of generation, and that towards
the age of maturity the difcriminating changes before mentioned appear 3
the male then lofmg that refemblance he had to the female in various
fecondary properties/ But that in all animals which are not of any diftind:
fex, called hermaphrodites, there is no fuch alteration taking place in
their form when they arrive at the age of maturity. It is evidently the
male which at this time in fuch refpefts recedes from the female. Every
female being at the age of maturity more like the young of the fame
fpecies than the male is obferved to be and if the male is deprived of
his teftes when young, he retains more of the original youthful form, and
is therefore more fimilar to the female.

From hence it might be fuppofed, that the female character contains
more truly the fpecific properties of the animal than the male j but the
charadter of every animal is that which is marked by the properties com-
mon to both fexes, which are found in a natural hermaphrodite, as a
fnail, or an animal of neither fex, as the caftrated male or fpayed female.

But where the fexes are feparate, and the animals have two characters,
neither of them can be called the true one ; the true diftinguifhing pro-
perties being thofe peculiar to neither fex, as above mentioned, which
are like wife found in the monftrous hermaphrodite. That thefe properties
give the diftin£t character of fuch animals is evident, for the caftrated
male and the fpayed female have both the fame common properties ; and
when I treated of the free martin, which is a monftrous hermaphrodite,
I obferved that it was more like the ox than the cow or bull, fo that the
marks charadteriftic of the fpecies which are found in the animal of a

^a This is not common to all animals of diftinft fexes ; for in the fifh there is no great dif-
ference, nor in many infects, nor in dogs, as has been already obferved ; however, it is con-
fiderable in many quadrupeds, but appears to be moft fo in birds.

K \' double

double fex, are imitated by depriving the individual animal of its fex by
art, by which means it only preferves the true properties of the fpecies.

In fome animals which have the fecondary properties we have men-
tioned peculiar to the two fexes, there is a deviation from all thofe ge-
neral rules, by a change of thefe fecondary characters; the female perfedt
with refpedt to the parts of generation, affuming more or lefs of the fe-
condary character of the male.

This however does not appear to arife from any action which takes
place at the firft formation of the animal, or grows up with it, but feems
to be one of thofe which is produced at certain periods of life, fimilar to
many common and natural phenomena ; like to what is obferved of the
horns of the flag, which differ at different ages ; or to the mane of the
lion, which does not grow till after his fifth year, &c.

This change has been obferved in fome of the bird tribe, but principally
in the common pheafant.

It is remarked by thofe who are converfant with this bird, when wild,
that there appears every now and then a hen pheafant with the feathers
of the cock ; and all that they have decided on the fubjedt is, that this
animal does not breed; and that its fpurs do not grow. Some years ago
one of thefe was fent to the late Dr. William Hunter, which I examined
and found it to have all the parts of the female peculiar to that bird.
This fpecimen is ftill preferved in Dr. Hunter\'s mufeum.

Dr. Pitcairn having received a pheafant of this kind from Sir Thomas
Harris, fhowed it as a curiolity to Sir Jofeph Banks and Dr. Solander.
I happened to be then prefent, and was deiired to examine the bird.
The following was the refult of my examination.

I found the parts of generation to be truly female: they were as perfect
as in any hen pheafant that is not in the leafl prepared for laying eggs.
There were both the ovaria and ovidudfc.

As the obfervations hitherto made have been principally upon birds
found wild, little of their hiftory can be known ; but from what took
place in a hen pheafant in the poffeffion of a friend of Sir Jofeph Banks,
it ihould feem probable that this character arifes from a change at a late
period of the animal\'s life, and does not grow up with it from the be-
ginning

ginning. This lady had for fome time bred pheafants, and paid parti-
cular attention to them. One of the hens, after having produced feveral
broods, moulted, and the fucceeding feathers were thofe of a cock. This
animal was never afterwards impregnated. Hence it is moft probable,
that all thofe hen pheafants which are found wild, and have the feathers
of a cock, were formerly perfect hens, but have become changed by age,
and perhaps by certain conftitutional circumftances,

I having bought fome pheafants from a dealer in birds, among which
were feveral hens, perceived that one of the hens, the year after, did not
lay, and began to change her feathers the year following fhe had nearly
thofe of the cock, but lefs brilliant, efpecially on the head. It is more
than probable this was an old hen, nearly under fimilar circumftances to
thofe before defcribed.

Lady Tynte had a favourite pyed pea-hen which had produced chickens
eight feveral times having moulted when about eleven years old, the
lady and family were aftonifhed by her difplaying the feathers peculiar to
the other fex, and appearing like a pyed peacock. In this procefs the
tail, which became like that of a cock, appeared firft after moulting.
In the following year fhe moulted again, and produced fimilar feathers,
In the third year fhe did the fame; then had fpurs refembling thofe of
a cock. She never bred after this change in her plumage, and died in
the following winter during the hard froft, namely, in the winter 1775-6.
This bird is now preferved in the mufeum of Sir Afhton Lever.¹

From what has been related of thefe three birds, may it not reafonably
be inferred, that all thofe wild pheafants of the female fex, which are
found refembling the cock, have changed the nature of their feathers at
a certain age P This not only obtains in the birds above mentioned,
but perhaps to a certain degree in every clafs of animals. We find fome-

1  It might be fuppofed, that this bird was really a cock which had been changed for a
hen ; but the following facts put this matter beyond a donbt. Firft, there was no other
pyed pea-fowl in the country. Secondly, the hen had knobs on her toes, which were the
fame after her change. Thirdly, fhe was as fmall after the change as before, therefore too
fmali for a cock. Fourthly, fhe was a favourite bird, and was generally fed by the lady, and
ufed to come for her food, which ihe ftill continued to do after the change in the feathers.

K 2 thing

thing fimilar taking place even in the human fpecies : for that increafe of
hair obfervable on the faces of many women in advanced life, is an
approach towards the beard, which is one of the moft diftinguifhing
fecondary properties of man.

Thus we fee the fexes which at an early period had little to diftinguifh
them from each other, acquiring about the time of puberty fecondary
properties, which clearly charadterife the male and female. The male
at this time recedes from the female, and a flumes the fecondary proper-
ties of his fex.

The female, at a much later time of life, when the powers of pro-
pagation ceafe, lofes many of her peculiar properties; and may be faid,
except from mere ftrudture of parts, to be of no fex; and even recedes
from the original character of the animal, approaching in appearance
towards the male, or perhaps more properly towards the hermaphrodite»

ACCOUNT

account of the organ of hearing in

FISHES.

N\'ATURAL hiftory has ever been confidered as worthy the attention

_ of the curious philofopher, and therefore has in all ages kept pace

with the other branches of knowledge; and as both arts and fciences have
of late years been cultivated to a degree perhaps beyond what was ever
known before, we find alfo that natural hiftory has not been neglected;
all Europe appears to be awake to it. In this ifland it has been purfued
with more philofophic ardour than what was ever known in any country.
It has become the ftudy of men poffeffcd of affluent fortune, which they
have not only dedicated to the cultivation of this fcience, but have even
rifked their health and lives in purfuit of it, fearching unknown regions
to improve mankind, fettling correfpondences every where, fo as to bring
in its materials into this country in order to make it the fchool of natural
hiftory. It is no wonder then that a fpirit of inquiry is diffufed through
almoft all ranks of men ; and that thofe who cannot purfue it themfelves,
yet chufing at leaft to benefit by the induftry of others, are eager to be
informed of what is already known.

Thefe refle&ions induced me to publifh this fhort account of the Organ
of Hearing in Fifhes; for though the exiftence of fuch an organ is now
more known, it is ftill a fubje£t of difpute with many, whether they pof~
fefs that fenfe or not.

Some time before I quitted my anatomical purfuits in the year 1760,
and went with the army to Bellifle, I had obferved this organ in fifhes,
and had the parts expofed and preferved in fpirits. In fome the canals
were filled with coloured injection, which fhowed them to great advantage;
and in others were fo prepared as to fit them to be kept as dried prepara-
tions/ My refearches, in that and in every other part of the animal

³ I have injefted thefe parts in other animals, both with wax and metals, and the bone
being afterwards corroded in fpirit of fea-falt makes elegant cafts of thefe canals..

ceconomv.

ceconomy, have been continued ever lince that time; yet I am Hill in-
clined to conlider whatever is uncommon in the ftrudture of thefe parts
in fifhes, as only a link in the chain of varieties difplayed in the forma-
tion of this organ of fenfe, in different animals, defcending from the moft
perfect to the moft imperfect, in a regular progrefiion.*

As in this age of invefb\'gation, a hint that fuch an organ exifted would
be fufficient to excite a fpirit of conjecture or inquiry, I was aware
that there would not be wanting fome men, who, whether they only
imagined the fad: to be true, or really found it to be fo, would be very
ready to believe the difcovery their own, and to a flu me all the merit of
it to themfelves. My attention was more ftrongly recalled to this point,
by hearing in converfation that fome anatomifts in France, Germany,
and Italy, had difcovered the organ of hearing in fifhes, and intended to
publifli on the fubjed. I therefore conceived that it would be only juffcice
to myfelf to deliver a fhort account of that organ to the Royal Society, of
which I had made a difcovery more than twenty years before. I have
thought it propei; to reprint it here, without adding any thing to what I
had before written on the fubjed j referving a more compleat inveftigation
of this part of natural hiftory for a larger work on the the ftrudure of
animals, which I one day hope to have it in my power to publifli.

I do not intend to give a full account of this organ in any one fifh,
or of the varieties in different fifhes, but only of the organ in general;
thofe therefore who may chufe to purfue this branch of the animal (Eco-
nomy may think it deficient in the defcriptive parts. If it was a difficult
tafk to expofe this organ in fifhes, I fhould perhaps be led to be more
full in my defcription of it; but there is in fad: nothing more eafy.

I may be allowed juft to obferve here, that the clafs called fepia has
the organ of hearing, but fomewhat differently conftruded from what it
is in fifhes.

^a The preparations to illuftrate thefe facts have been ever fince fhewn in my collection to
both the curious of this country and foreigners : in (hewing whatever was new, or fup-
pofed to be new, the ears of fifhes were always confidered by me as one important article.

The

The organ of hearing in fillies is placed on the fides of the fkull,
or cavity which contains the brain ; but the fkull makes no part of
the organ, as it does in the quadruped and the bird, the organ itfelf
being a diflindt and detached part. In fome fifhes the organ is wholly
fiirrounded by the parts compofing the cavity of the fkull, as in the ray
kind.

In others this organ is in part within the fkull, or that cavity which
contains the brain, as in the falmon, cod, &c. the fkull projecting late-
rally, and forming a cavity.

The organ of hearing in fifhes appears to increafe with the animal,
for it is nearly in the fame proportion with that of the animal; which is
not the cafe with the quadruped, the organs being in them nearly

as large in the growing fcetus as in the adult.

It is much more fimple in fifhes than in all thofe orders of animals
which may be reckoned fuperior, fuch as quadrupeds, birds, and amphi-
bious animals ; but there is a regular gradation from the firft of thefe to
fifhes.

It varies in different orders of fifhes; but in all it confifls of three
curved tubes which unite with one another; this union forms in fome
only one canal, as in the cod, falmon, ling, &c. and in others a pretty
large cavity, as in the ray kind. In the jack there is an oblong bag,
or blind procefs, which is an addition to thofe canals, and which com-
municates with them at their union. In the cod, &c. this union of the
three tubes flands upon an oval cavity, and in the jack there are two; the
additional cavities in thefe fifhes appear to anfwer the fame purpofe with
the cavity in the ray or cartilaginous fifhes, which is the union of the
three canals.

The whole organ is compofed of a kind of cartilaginous fubftance,
very hard or firm in fome parts, and which in fome fifhes is crufted over
with a thin bony lamella, fo as not to allow it to collapfe; for as the
fkull does not form any part of thofe canals or cavities, they muft be
compofed of a fubftance capable of keeping its form.

Each

Each tube defcribes more than a femi-circle. This refembles in fome
refped what we find in moft other animals, but differs in the parts being
diftindt from the fkull.^a

Two of the femi-circular canals are fimilar to one another, may be
called a pair, and are placed perpendicularly ; the third is not fo long ;
in fome it is placed horizontally, uniting as it were the other two at their
ends or terminations. In the fkate this is fomewhat different, being only
united to one of the perpendicular canals. The two femi-circular canals
whofe pofition is perpendicular, are united at one end laterally, forming
one canal; at their other extremities they have no connection with each
other, but are joined to the terminations of the horizontal one, near its
entrance into the common cavity. Near the union of thofe canals into
the common, they are fvvelled out into round bags, becoming there
much larger.

In the ray kind they all terminate in one cavity _; and in the cod they
terminate in one canal, placed upon the additional cavity or cavities, in
which there is a bone or bones. In fome there are two bones • and in
the jack, which has two cavities, we find in one of them two bones, and
in the other one; in the ray there is only a chalky fubflance.^b

In fome fifhes the external communication, or meatus, enters at the
union of the two perpendicular canals. This is the cafe with all the
ray kind, the external orifice being fmall, and placed on the upper flat
furface of the head; but it is not every genus or fpecies of fifhes that
have the external opening.

The nerves of the ear pafs outwards from the brain, and appear to ter-
minate at once on the external furface of the fwelling of the femi-circular
tubes above defcribed. They do not appear to pafs through thefe fo as
to get on the infide, as is fuppofed to be the cafe in quadrupeds I fhould
therefore very much fufpedt, that the lining of the tubes in the quadruped
is not nerve, but a kind of internal periofteum.

^a The turtle and the crocodile have a ftru&ure fomewhat fimilar to this ; and the intention
is the fame, for their fkulls make no part of the organ.

^h This chalky fubftance is alfo found in the ears of amphibious animals.

As

As it is evident that fifties pofiefs the organ of hearing, it becomes un-
neceftary to make or relate any experiment made with live fifties, which
only tends to prove this fad:; but I will mention one experiment to fhow
that founds affedt them much, and is one of their guards, as it is in other
animals. In the year 1762, when I was in Portugal, I obferved in a
nobleman\'s garden, near Lilbon, a fmall fifti-pond full of different kinds
of fifti. Its bottom was level with the ground, and was made by forming
a bank all round; with a fhrubbery clofe to it. Whilft I was lying on
the bank, obferving the fifti fwimming about, I deft red a gentleman, who
was with me, to take a loaded gun and go behind the ftirubs and fire it.
The reafon for going behind the ftirubs was, that there might not be the
leaft reflection of light. The inftant the report was made, the fifti feemed
to be all of one mind, for they vaniftied inftantaneoufty, railing as it were
a cloud of mud from the bottom. In about five minutes afterwards they
began to appear, and were feen fwimming about as before.

Geoffroi, who has written on this organ, confiders the ray as in the
clafs of reptiles; and with that idea has examined their organ of hearing.
He is by no means clear in his defcription, fo that it is almoft impoftible
to follow him ; yet it is but doing him juftice to allow, that he has dif-
covered what is analogous to the three femi-circular canals in other
animals, together with their union into one cavity; and mentions the
chalky fubftance contained in that cavity and the nerves. But it is by no
means clear, that he was acquainted with the external opening which
leads to thofe canals. He fays the entrance of the organ of hearing (by
which one would fuppofe he means the meatus auditorius externus) is
not eafily difcovered; neither does that which he defcribes correfpond
with the real fituation of the external communication ; we may therefore
reafonably conclude that he is defcribing fomething elfe. He is not more
clear in his mode of reafoning on the application of the parts to produce
the fenfe of hearing. He obferves that the organ of hearing is very im-
perfedt in this fpecies of animals; but fuppofes that to be compenfated by
the medium in which they live, and by which found is conveyed to them
being more denfe than that of the air, by which found is communicated to

L animals

animals living on the land; and of this idea he is certainly the author*
Monf. GeofFroi cannot indeed be faid to have given a perfed: account of
the organ of hearing in fifhes, yet on the whole he fhould be confidered
as a difcoverer. For though he had only made his obfervations on the
ray, as belonging to the clafs of reptiles; yet as it may be properly con-
lidered of the fifh kind, he has a juft claim to the difcovery. Had I
formerly been acquainted with this author\'s refearches and pretenfions, I
fhould not have claimed a difcovery to which I had not a prior right;
nor fhould I have held the difcovery of the external communication alone,
an objedt of confequence enough to induce me to difpute the honour with
Monf. GeofFroi.

In looking over the works of the different authors who have treated of
the organ of hearing in fifhes, I find from a paffage in Willoughby,^a
who publifhed prior to Mr. GeofFroi, and indeed is quoted by him, that
my claim, even to the difcovery of the external opening, is not fo flrong
as I believed it to be; for he mentions an external orifice in the fkate,
Contiguous to what he fuppofes the organ of hearing in that fifh. If what
he alludes to is really the external opening of the ear, it gives him a prior
claim to the difcovery of that part of the organ; although from his
account, he cannot be faid to have been acquainted with the organ
itfelf: but as we find in defcribing the external ear of the thornback
that he has evidently miflaken the nofe for it, of which he gives a
tolerable full account, it is very obvious that he was ignorant of the open-
ing into the ear.^b

Although profeffor Camper publifhed an account of the organ of
hearing in fifhes fo late as 1774, he did not feem at that time to have
been acquainted with the external opening of the ear in the ray. After
giving a defcription of the organ of hearing in the pike, he makes fome
general obfervations on the fimilarity of this organ in other fifhes ; but

* Willughbeii Hiftoria Pifcium, Oxonii 1686, lib, iii,. cap.. viii_a.

^b Lib. iii, cap,, xiv.

excepts

excepts the fliark and ray.^a This exception we might fuppofe alluded to
the auditory canal -, but further on he explains what he meant by this
exception, and does not mention the external opening in the ray ; from
which we may fairly conclude that he was not acquainted with it.^b

^a " II eft très-vraifemblable que toutes les autres efpèces de poiffons, tant malacopterygh
qu\'acanthopterygii, aufïï-bien que les branchiojlegi & les chondropterygii d\'Artedi, à l\'exception
des fqualis & des raies, ont l\'organe de l\'ouïe conftruit à peu près de la même façon ; je
n\'excepte pas l\'efturgeon, quoique M. Klein, ibid, ait donné la defcription du conduit auditif,
page 19, figure A,\\ Tab. 2, b -, ce poiffon étant rare parmi nous, je n\'ai eu occafion de l\'exa-
miner qu\'une feule fois fans avoir trouvé ce conduit." Mémoires Etrangers de l\'Academie
des Sciences, 1774, tom. 6, page 190.

^b " Au contraire, les chiens de mer, les galeîs rlp Rnnrlelpt- &• It?e poiïï"ons qu\'il a décrits,
lib. XII ; les fqualis d\'Artedi & les raies, ont bien l\'organe à peu près de la même compo-
fition, mais il eft enfermé dans une caille tout oïïeufe ou cartilagineufe, ce qui ne fait pas une
différence effentielle ; ils entendent donc comme les églefins, les morues, les baudroyes Se les
brochets, en un mot comme tous les autres poiffons non amphibies : M. Geoffroi s\'eft trompé
en comparant leurs organes avec celui des reptiles, tels que la vipère, les lézards, &c. qui
entendent le fon comme les quadrupèdes, les oifeaux & les amphibies aquatiques, favoir par
le moyen de l\'air & d\'un tambour, comme j\'ai deflèin de le prouver dans une autre occafion."
Mémoires Etrangers de l\'Acadamie des Sciences, 1774, tom. 6, page 190.

ACCOUNT

ACCOUNT OF CERTAIN RECEPTACLES OF AIR
IN BIRDS, WHICH COMMUNICATE WITH THE
LUNGS AND EUSTACHIAN TUBE.

Society, in the year 1774, I have by the diffe&ions of a number of
birds been able to make fome additional obfervations relative to the extent
of the air-cells which communicate with the lungs in this clafs of ani-
mals. Thefe latter oblervations were not however made in confequence
of any regular defign to inveftigate this fubjeft further. For to have
eftablifhed the principle feemed all that was neceffary, unlefs by general
obfervations we could hope to throw more light on the final intention of
this remarkable piece of mechanifm.

Before the period I have mentioned, the communication fubfifting in
birds, between the air-cells of the lungs and other cavities of the body,
had not been clearly explained, nor even much attended to by anatomifts
or natural historians. It is a Angularity of itrudure peculiar to this tribe
of animals 5 and an account of it, cannot, I imagine, be unacceptable
to the public.

It is not my prefent intention to enter into minute defcriptions of all
the particular communications of this fort difcoverable in birds by dif-
feftion, but only to mention fuch general fadts as will ferve to introduce
the fubjedt into natural hiftory, and lead to an inquiry into the purpofes
which this ftrudture was intended to anfwer. With this view I Shall en-
deavour to give fome idea of the conftrudtion of the lungs, and of the
air-receptacles in birds; occasionally remarking the circumftances in
which thefe principally differ from what i& feen in other animals.

To make this matter more intelligible, I muft previously give an idea
of the difference between the particular parts in queStion, and thole of
other animals, who are not endowed with this property • and iirft, the
conStru&ion of the lungs, and then of thofe receptacles«

The

The mechanifm of the lungs in birds, which renders them lit for
conveying air to different parts of the body, confifts principally in certain
communications.

It has been afferted that birds have no diaphragm ; but this opinion
muft have arifen either from a want of obfervation, or from too confined
an idea of a diaphragm ; for there is a moderately ftrong, but thin and
tranfparent, membrane which covers the lower furface of the lungs,
adheres to them, and affords insertion to leveral thin mufcles which arife
from the inner furfaces of the ribs. The ufe of this part feems to be
that of leffening the concavity of the lungs towards the abdomen, at the
time of infpiration, and thereby aflifting to dilate the air-cells for which
reafon it is to be confidcred as anfwering one main purpofe of a dia-
phragm. Befides this attachment of the lungs to the diaphragm, they
are alfo connected to fhe ribs, and to the fides of the vertebrae.

Thefe adhefions are peculiar to this tribe of animals, and are of An-
gular ufe, nay in fa£t are abfolutely neceffary in fuch lungs as thofe of
birds; out of whicljt it is intended the air fhould find a paffage into other
cavities. For if the lungs were loofe in the cavity of the thorax, as is
the cafe in many other animals, thefe cells could not be expanded, either
by the deprefiion of the diaphragm, or the elevation of the ribs; fince
the air rufhing in to fill up the vacuum produced in the cavity of the
cheft by thefe actions would take the {freight road from the trachea
through thefe paflages, and of confequence would expand no part of the
lungs which lay out of that line, whereby refpiration would be totally
prevented, and an effect produced exactly fimilar to what happens in other
animals where the lungs are fo much wounded as to allow a free exit to
the air at that part.

The cells in birds which receive air from the lungs, are to be found
both in the foft parts, and in the bones; and have no communication
with the cavity of the common cellular membrane. Some of thefe air-
bags are placed in the larger cavities, as the abdomen ; and others are
fo lodged in the interfaces, as about the breaft, axilla, &c. as at firft to
give the appearance of the common connecting membrane. Some of
them communicate immediately with one another; and all may be faid

to

to have a communication by means,of the lungs. They are of very dif-
ferent fizes, juft as bell fuits the particular circumftances of the parts in
which they are placed.

The bones which receive air are of two kinds ; fome, as the fternum,
ribs, and vertebra, have their internal fubftance divided into innumerable
cells, whilft others, as the os humeri, and the os femoris, are hollowed
out into one large canal, with fometimes a few bony columns running
acrofs at the extremities. Bones of this kind may be diftinguifhed from
thofe that do not receive air, by feveral marks : ift, By their lefs fpecific
gravity : 2dly, By being lefs vafcular than the others, and therefore
whiter : 3<ily, By their containing little or no oil, and confequently being
more eafily cleaned; and when cleaned appearing much whirer than com-
mon bones : 4-thly, By having no marrow, or even any bloody pulpy fub-
ftance in their cells : 5thly, By not being in general fo hard and firm as
other bones³; and 6thly, By the paffage that allows the air to enter
the bones, which can eafily be perceived. In the recent bone we may
readily difcover holes, or openings, not filled with any fuch foft fubftance
as blood-veffels or nerves ; and it happens that feveral of thefe holes are
placed together, near that end of the bone which is next to the trunk of
the bird; and are diftinguifhable by having their external edges rounded
off; which is not the cafe with the holes through ivhich either nerves or
blood-veffels pafs into the fubftance of the bone.

When birds break any of the bones which contain air, the furround-
ing parts become emphyfematous.

There are openings in the lungs, by which they tranfmit air to the
other parts; and the membrane or diaphragm above mentioned is per-
forated in feveral places with holes of a confiderable fize, which admit of
a free communication between the cells of the lungs and the abdomen,
a circumftance which has been frequently noticed. To each of thefe
perforations is joined a diftindt membranous bag, extremely thin and
tranfparent, which being afterwards continued through the whole of the

^a The bones of fome birds are fb foft that they can be fqueezed together with the finger
and thumb; the bones of the extremities however have very folid fides.

abdomen

abdomen are attached to the back and fides of that cavity, by which the
bags are kept firm in their proper fituations ; each receiving the air from
their refpe£tive openings. There is no occafion to defcribe here all the
bags, or their attachments, it being fufficient to fay that they extend over
the whole abdomen.

The lungs at the anterior part, contiguous to the fternum, open into
certain membranous cells which lie upon the fides of the pericardium,
and communicate with the cells of the flernum. At the fuperior part
the opening of the lungs is into the large cells of a loofe net work,
through which the trachea, cefophagus, and large veffels pafs as they are
going to and from the heart. When thefe cells are diftended with air,
the fize of that part where they lie is very confiderably increafed, and in
general is a mark of either the pafiion of anger or love. It is plainly
feen in the Turkey-cock, the pouting pigeon, &c. and is very vifible in
the bread of a goofe when Hie cackles. Thefe cells communicate with
others in the axilla, under the large peroral mufcle; and in fome birds
are ftill further extended. In the pelican, for inftance, the fkin of the
breafl is united to the parts underneath by means of thofe cells, which
are pretty equally formed; and when the fkin is removed, the two fepa-
rated furfaces appear as if honey-combed. When thefe cells are diftended,
the fkin is removed to a confiderable diftance, by which means the volume
is proportionally increafed. In moft birds, I believe in all that fly, thefe
axillary cells communicate with the cavity of the os humeri, by means of
fmall openings in the hollow lurface near the head of that bone. The
oftrich however is an exception. In fome birds they are continued down
the wing, where they communicate with the ulna and radius, and in
others they go even as far as the pinions.

The pofterior edges of the lungs (which lie on the fides of the fpine
and project backwards between the ribs) open into the cells of the bodies
of the vertebrae, into thofe of the ribs, the canal of the medulla fpinalis,
the cells of the facrum, and other bones of the pelvis ; from which parts
the air finds a paffage into the cavity of the thigh bone. This takes
place in the greateft number of birds • but in fome the air is even con-
tinued part of the way down the thighs. This account agrees with what

we

we generally find j though fome birds have more, and Tome fewer of thefe
communications ; for in the oftrich no air gets into the os humeri, but
it enters into every other part, as defcribed above, and in very large quan-
tities. In the common fowl no air appears to enter any bone except the
os humeri. The wood-cock has no air-cells either in the firft bone of
the wing, or in the thigh bones. On the other hand, in the pelican
the air paffes on to the ulna and radius, and into thofe bones which
anfwer to the carpus and metacarpus of quadrupeds.

Thus the cells of the abdomen, thofe furrounding the pericardium,
thofe fituated at the lower and forepart of the neck, and in the axilla,
thofe in the cellular membrane under the pedtoral mufcles, as well as in
that which unites the fkin to the body, all communicate with the lungs, :
and are capable of being filled with air; and again from thefe the cells of
the fternum, ribs, vertebra of the back and loins, bones of the pelvis,
the humeri, the ulna and radius, with the pinions, and thigh bones,
can in many birds be furnifhed with air.

This fupply of air is not conveyed to the bones folely by means of the
lungs i for the cells of the bones of the head in fome birds are likewife
filled with it, of which the owl is a remarkable inftance. In this bird
the diploe between the two plates of the fkull i& cellular and admits a
confiderable quantity of air, which is furnifhed by the Euflachian tube.

Some authors confidered the diploe in the cranium of a bird as a con-
tinuation of the mamillary procefs,^a and have looked upon it as a circum-
flance peculiar to finging birds, but this is not really the cafe. The
lower jaw of many birds, but more particularly the pelican, is furnifhed
with air, which is fupplied by means- of the Eufiachian tube,^b

Thefe

^a The only thing fi\'milar to: this communication in birds, of the cells of bones with the
«xternal air, is that which takes place in the internal ear of quadrupeds, by means of the Euf-
tachian tube.

» When I wrote this account to fend it. to the Royal Society, I did not then know by what
means this was done ; for in that I faid, " but by what means I do not know;" that is, I
did not know whether it was conveyed by the trachea, where it pafles along the neck, or
the E»jftachian tube. Profeflbr Camper, when he did me the honour to call upon me, was fo

M obliging

Thefe facts, which had been formerly obferved, led me in the year
1758 to make feveral experiments upon the breathing of birds, to prove
the free communication between the lungs and the above mentioned parts.

Firft, I made an opening into the belly of a cock, and having intro-
duced a filver canula, tied up the trachea; I found that the animal
breathed by this opening, and might have lived; but by an inflammation
in the bowels coming on, adhefions were produced* and the communi-
cation cut off.

I next cut the wing through the os humeri, in another fowl, -and
tying up the trachea, as in the cock, found that the air paffed to and
from the lungs by the canal in this bone. The fame experiment was
made with the os femoris of a young hawk, and was attended with
nearly the like fuccefs. But the paflage of air through the parts in
both, efpecially in the laft experiment, was attended with more difficulty
than in the fir ft; it was indeed fo great as to render it impoffible for the
animal to live longer than to prove evidently that it breathed through
the cut bone.

I have made feveral preparations of thefe cells, by throwing into the
trachea an injection commonly called the corroding injection, which firft
filled the air-cells of the lungs, then all the others, fuch as the cells in
the abdomen, anterior and fuperior part of the cheSt, axilla, os humeri,
cells of the back bone and thigh ; then the whole being put into fpirit of
fea-falt, and corroded, the caSt ofinjedtion came out entire.

The extreme fmgularity of thefe communications in birds, put me upon
confidering what might be their final intention. At firft I fufpedted that
it might be intended to affiSt the ad: of flying, that being the circumstance
which appears the molt peculiar to birds. It might be of fervice in that
refped, I thought, by increafing the volume and Strength with the fame
quantity of matter, and therefore without adding to the weight of the
whole, which indeed would rather be diminished by the difference of

obliging as to take Some pains to fhow me, in the lower jaw of the hawk, the hole where the
air entered ; which makes me fufpeft he did not underftand what I had written. For after
having given the marks by which fuch openings were particularly diftinguifhed, it will hardly
be fuppofed I could fay that I did not know the hole where the air entered.

Specific

fpecific gravity between the external and internal air. This opinion was
ilrengthened, by obferving that the feathers of birds contain alfo a confi-
derable quantity of air and in the very part which requires the greateffc
ftrength: the analogy to which feems to hold good between this mechanifm
in birds ; and what is difcoverable in moft kinds of fifhes, rather favours
this opinion. For thefe have air contained within their bodies, which I
believe is commonly fuppofed to leffen their fpecific gravity, although this
does not appear fo neceffary in fifhes, who move in a much heavier ele-
ment than birds.³ But when I found that the oftrich (which is not

intended

^a When we confider that the elevating and fufpending apparatus is much lefs In /Iflies than
in birds, we might reafonably conceive the air in them was intended as a kind of equilibrium
between the fifh and water; and that progreflive motion was the only thing wanted in the
a£Hons of fifties. Were we to reafon upon general principles alone, we fhould fuppofe that
thofe fifties who have the largeft air-bags fhould have their mufcles of a greater fpecific gra-
vity j and thofe fifties that have none, fhould have the lighteft flefti; therefore that the flefh
of a fhark, which has no air-bag, fhould be lighter than that of the falmon and cod, which
have : but to know how far this, which appeared to be reafonable, was a fact, I made the fol-
lowing experiments.

Experiment x. I took a portion of mufcle of the fhark, cod, and falmon, of the fame
weight in air; and firft examined how far they occupied the fame fpace, by immerfing them
in water, and obferving the rife or fall of the water upon each of them being feparately im*
merfed in it.

The fhark occupied the fmalleft fpace, the felmon a little more, and the cod the largeft.

Experiment 2. I then fufpended the fame three portions, upon a level, in a glafs veflel
filled with water about two feet high, and let them all go at the fame inftant to fee which
would fall through the water in the fhorteft fpace of time, The fhark got to the bottom
firft, the falmon next, and the cod laft.

It is neceffary to obferve that, in both thefe experiments, the difference iabulfc, and in the
times of their falling was very little ; but however fufficient to afcertain the fact for which the
experiments were inftituted.

To fee how far the mufcular flefti of birds was fpecifically lighter than that of a quadruped,.,
I repeated the above experiments upon a portion of a hind, of a pigeon, and of a ftieep, but
could difcover no vifible difference in their weight..

It may be obferved, there are two lituations of oil in fifties; in one it is- diffufed through
the body, as in the falmon, herring, &c. In the other it is in the liver, as in all of the ray
kind, cod, &c. and thofe w;ho have it in one part have none in the other. The liver, in
thofe of the ray kind, is large and extended through the. belly; therefore it might be fuppofed
to lighten the body, from oil being lighter tljan water or the flefh; but we have oil" in the

M 2 liver.

intended to fly) was amply provided with thefe cells; and that the com-
mon fowl, and many others of that clafs, which are endowed with the
faculty of flying, were lefs liberally fupplied with air : when I law that
the wood-cock, which flies, and is even fuppofed a bird of paffage, was
inferior in this refpeCt to the oftrich; and that the bat differed not in
ftrudture from animals that do n-ot fly, I was compelled, by fo many con-
tradictions to theory, to fuppofe that this lingular mechanifm might be
intended for fome other purpofe.

The next conje&ure that offered, was, that thefe parts were to be con-
sidered as an appendage to the lungs; to which I was led by the analogy
obfervable in amphibious animals. For in the fnake, viper, and many
others of them, the lungs are continued down through the whole belly,
in form of two bags; of which, the upper part only can perform the
office of refpiration with any degree of effect; the lower having com-
paratively but few air-veffels. The air mult pafs through this upper
part before it gets to the lower in infpiration, and muft alfo repafs in ex-
piration, fo that the refpiratory furface has more air applied to it than
what the lungs of themfelves could contain. It cannot however be fup-
pofed, that the air may be made to pafs to and fro in bones as in parts
which admit of contraction and dilatation ; the purpofe anfwered by thefe
bony cells muft therefore be different; and perhaps they fhould be con-
fidered as refervoirs of air. There is in fa£t a great fimilarity between
birds and that clafs of animals called amphibious ; and although a bird
and a fnake are not the fame in the conftru<5Uon of the refpiratory organs,
yet the circumftance of the air paffing in both beyond the lungs, into the
cavity of the abdomen, naturally leads us to fuppofe, that a ftru&ure fo
jimilar is defigned in each to a fimilar purpofe. This analogy is ftill
further fupported by the lungs in both confifting of large cells. Now
in amphibious animals, the ufe of fuch a conformation of the lungs is
evident * for it is in confequence of this ftru&ure that they require to
breathe lefs frequently than others. Even confidering the matter in this

Hver of the cod; and in the falmon, &c. there is a great deal of oil diffufed through the
whole; therefore I am affraid we are not yet acquainted with the full effect of the air-bladder
in fifties.

light, it may ftill, in birds, have fome connexion with flying, as that
motion may eafily be imagined to render frequency of refpiration incon-
venient, and a refervoir of air may therefore become Angularly ufeful.
Although we are not to coniider this ftrudlure in birds to be an extention
of lungs, yet I can eafily conceive this accumulation of air to be of great
ufe in refpiration ; for as we obferved in the viper, that the air in its paf-
fage to and from thefe cells, mufl certainly have a confiderable eftedt
upon the blood in the lungs, by allowing a much greater quantity of air
to pafs in a given time than if there was no fuch contraction of parts.¹
And this opinion will appear not to be ill founded, if we confider that
both in the bird and the viper, the furface of the lungs is fmall in com-
panion to what it is in many other animals which have not this exteilfioil
of cavity. It is alfo a corroborating circumftance, that in the fowl the
air could have paffed by a much readier way than through the lungs,
into all the cells about the breaft, neck, axilla, wings, &c. that could
have been filled from the lower end of the trachea, upon which many of
them lie. But the air muft now take a roundabout paflage both in its
way in and in its way out, thofe openings being upon the exterior furface
of the lungs. We mufl: not however give up the idea of luch ftru£ture
being of ufe in flying; for I believe we may fet it down as a general
rule, that in the birds of longeft and higheft flight, as eagles, this ex-
tenlion, or diffufion of air is carried further than in the others; and this
opinion is flrengthened by comparing this ftru&ure with the refpiratory
organs in the flying infects, which are compofed of cells diffufed through
the whole body and thefe are extended even into the head and down the
extremities j while there is no fuch ftruchire in thofe infects that do not
fly, as the fpider but why the pelican fhould be fo amply provided, I
cannot fay, not knowing the natural hiftory of that bird Efficiently to
be able to judge of this point. Do they carry weights in the large fauces
fo as to require fuch an increafe of body without increafe of weight ?

³ It may perhaps occur to fome that the whole of thefe communicating cells are to be con-
fidered as extended lungs; but I can hardly think that any air which gets beyond the vefi-
culated lungs themfelves is capable of affe&ing the blood of the animal; as the other cavities
into which it comes, as well thofe of the foft parts as of the bones, are very little vafcular.

How

How far this conftrudlion of the refpiratory organs may afiift birds in
finging, is deferving of notice ; as the vail; continuance of long, between
the breathings, in a Canary-bird, would appear to arife from it. This
is a fubjed however which I ilia 11 not at prefent enter upon,

EXPERIMENTS

r 8; J

EXPERIMENTS AND OBSERVATIONS ON ANI-
MALS, WITH RESPECT TO THE POWER OF
PRODUCING HEAT.

SOME late Ingenious experiments and observations, publifhed in the
Philofophical Tranfa&ions, upon a power which animals feem to
poffefs of generating cold, induced me to look over my notes, containing
iome which I had made in the year 1766, indicating an oppofite power in
animals, whereby they are capable of refitting any external cold while alive,
by generating within themfelves a degree of heat Sufficient to counteract it.
Thefe experiments were not originally inflituted with any expectation of
the event which refulted from them, but for a very different purpofe j
which was 110 other than to fatisfy myfelf, whether an animal could re-
tain life after it was frozen, as had been confidently aflerted both of fiflies
and fnakes. If I had fucceeded, I meant to have tried the effedts of freez-
ing, on living animals, to a much greater extent than ever can happen
accidentally. For that fnakes and fiflies, after being frozen, have flill
retained fo much of life, as when thawed to refume their vital anions, is
a fa£t fo well attefted that we are bound to believe it. I mention thefe
circumftances, to account for what might otherwife be attributed to
negligence and inattention; namely, the little nicety that was ufed in
meafuring the precife degree of cold applied in thefe experiments. Ac-
curacy in this particular was not aimed at, as it was of no confequence in
the inquiry more immediately before me. The cold was firfl produced
by means of ice and fnow with fal ammoniac or fea-falt, to about the
io° of Fahrenheit\'s thermometer: then ice was mixed with fpirit of
nitre; but what degree of cold was thus produced I did not examine.
This cold mixture was made in a tub furrounded with woollen cloths,
and covered with the fame, to prevent the effects of the heat of the at-
mofphere upon the mixture itfelf, and to preferve as much as poflible a
cold atmofphere within the veffel. The animal juices, the blood for ex-
ample,,

ample, freeze at 25°^ fo that a piece of dead flefh could be frozen in
fuch an atmofphere.

EXPERIMENTS.

I. The fir ft experiment was made on two carp. They were put into
a glafs veffel with common river water, and the veffel put into the freez-
ing mixture ; the water did not freeze faft enough ; and therefore to make
it freeze fooner we put in as much cooled fnow as to render the whole
thick. The fnow round the carp melted : we put in more frefh fnow,
which melted alfo and this was repeated feveral times, till we grew
tired, and at laft left them covered up in the yard to freeze by the joint
operation of the furrounding mixture and the natural cold of the atmof-
phere. They were frozen at laft, after having exhaufted the whole powers
of life in the production of heat. That this was really the cafe, could
not be known till I had completed that part of the experiment for which
the whole was begun, viz. the thawing of the animals. This was done
very gradually; but the animals did not, with flexibility, recover life.
While in this cold they fhewed figns of great uneafmefs by their violent
motions. N. B. In fome of thefe experiments, where air was made the
conductor of the cold and heat, that the heat might be more readily
carried off from the animal, a leaden veffel was ufed. It was fmall for
the fame reafon ; and as it was neceflary for the animal\'s refpiration that
the mouth of the veffel fhould communicate with the open air, it was
made pretty deep, that the cold of the atmofphere round the animal
might not be diminifhed faft by the warmth of the open air, which would
have fpoiled it as a conductor.

II. The fecond experiment was upon a dormoufe. The veffel was
funk in the cold mixture almoft to its edge. The atmofphere round the
animal foon cooled _; its breath froze as it came from the mouth; an
hoar-frofl gathered on its whifkers, and on all the infide of the veffel;
and the external points of the hair became covered with the fame. While
this was going on, the animal fhewed figns of great uneafinefs : fometimes
it would coil itfelf into a round form, to preferve its extremities, and con-
fine

fine its heat; but finding that ineffectual, it then endeavoured to make
its efcape³; its motions became lefs violent by the linking of the vital
powers; and its feet were frozen ; but we were not able to keep up the
cold a fufficient time to freeze the whole animal, its hair being fo bad a
conductor of heat, that the consumption was not more than the animal
powers were capable of Supporting.,^b

III. The third experiment was made upon another dormoufe. From
the failure of the laft experiment I took care that the hair Should not a
fecond time be an obftruCtion to the fuccefs of our experiment. I there-
fore firft made it wet all over, that the heat of the animal might be more
inftantaneoufly carried off; and then it was put into a leaden veffel. The
whole was put into the cold mixture as befnre The animal foon gave
figns of its feeling the cold, by repeated attempts to make its efcape.
The breath, and the evaporating water from its body were foon frozen,
and appeared like a hoar-froft on the fides of the veffel, and on its
whifkers ; but while the vigour of life lafted, it defied the approach of
the cold. However, from the hair being wet, and thereby rendered a
good conductor of heat, there was a much greater confumption of it than
in the former experiment. This haftened on a diminution of the power
of producing it. The animal died, and foon became Stiff; upon thaw-
ing it, we found it was quite dead.

IV. The fourth experiment was upon a toad. It was put into water
juft deep enough not to cover its mouth, and the whole was put into a
cold mixture, now between io° and 15⁰. It allowed the water to freeze
clofe to it, which as it were, clofed it in ; but the animal did not die,
and therefore was not frozen : however, it hardly ever recovered the ufe
of its limbs.

^a This Shows, that cold carried to a great degree rather roufes the animal into action than
depreiles it; but it would appear from many circumftances and obfervations, that a certain
degree of cold produces inactivity both in the living and fenfative principle, which will be
further illuftrated hereafter.

^b Thefe experiments were made in prefence of Dr. George Fordyce and Dr. Erwin,
teacher of Chymiftry at Glafgow; the latter of whom came in accidentally in the middle
of our operations.

N \' V. The

V. The fifth experiment was with a fnail, which froze very foon, in
a cold between i o° and 13⁰ j but thefe two laft experiments were made in
the winter, when the living powers of thofe animals are very weak : they
might have refilled the cold more ftrongly in the fummer. Why the
animals mentioned in thefe experiments died before they were frozen,
while thofe which are expofed to the atmofphere in very cold climates
do not, is a point I fhall not pretend to determine ; not knowing the
difference between the effects of a natural and an artificial cold. It may
be accounted for, by fuppofing that the natural cold in climates in which
animals are found frozen, is fo intenfe as to produce congelation imme-
diately, before the powers of life are exhauftedj at leaft whether it is
fo or not is worthy of inquiry.

It appears from the above experiments, that moft probably the animals-
were deprived of life before they were frozen. Secondly, that there was
an exertion or expence of animal powers in refifting the effe&s of cold,
proportioned to the neceffity. Thirdly, that this exertion was in propor-
tion to the perfection of the animal, and the natural heat proper to each
fpecies, and to each age. It might alio perhaps depend in fome degree on
other circumftances not hitherto obferved: for from experiment II. and
III. upon dormice, I found that in thefe animals, which are of a confti-
tution to retain nearly the fame heat in all temperatures of the air, it
required the greateft cold I could produce to overcome this refifting
power; while by experiment IV. and V. in the toad and fnail, whojfe
natural heat is not always the fame, but is altered very materially accord-
ing to the external heat or cold, this power was exhaufted in a degree of
cold not exceeding io° or 15⁰: and the fnail being the moft imperfedt of
the two, its powers of generating heat appeared to be much the weakeft.

That the imperfedt animals will allow of a confiderable variation in
their temperature of heat and cold, is proved by the following experi-
ments. The thermometer being at 45% the ball was introduced by the
mouth into the ftomach of a frog, which had been expofed to the fame
cold. It rofe to 49⁰. I then placed the frog in an atmofphere made
warm by heated water, where I allowed it to flay twenty minutes ; and
upon introducing the thermometer into the ftomach, it raifed the quick-

filver

filver to 64°. But to what degree the more imperfect animals are capa-
ble of being rendered hotter and colder at one time than another, I have
not been able to determine. The torpidity of thefe animals in our winter
is probably owing to the great change wrought in their temperature by
the external heat and cold. The cold in their bodies is to fuch a degree,
as in a great meafure to put a ftop, while it lafts, to the vital functions;
while in warmer climates no fuch effed is produced. This variety not
only takes place in animals of different orders; but in fome degree in
the fame animal at different ages, even according to the different ages of
parts in the fame animal; for an animal is naturally alike old in all its
original parts, yet there are often new ones formed in confequence of
difeafes • and we find, that thefe new or young parrs in animals are not
able to fupport life equally with the old j but as animals are of different
ages, and the fame animal is always growing older, and of courfe more
and more perfect, they then become more capable of generating heat
than when they were younger.

This power of generating heat feems to be a property in an animal
while alive. It is a power only of oppofition and refinance; for it is
not .found to exert itfelf fpontaneoufly and unprovoked ; but muff always
be excited by the energy of fome external frigorific agent, or difeafe. It
does not depend on the motion of the blood, as fome have fuppofed, be-
caufe it likewife belongs to animals who have no circulation ; and the
nofe of a dog, which is always nearly of the fame heat in all tempera-
tures of the air, is well fupplied with blood: neither can it be faid to
depend upon the nervous fyftem, for it is found in animals that have no
brain or nerves. It is then moft probable that it arifes from fome other
principle; a principle fo connected with life, that it can, and does, ad:
independently of circulation, fenfation; and volition -_K and is that power
which preferves and regulates the internal machine. This power of
generating heat is in the higheft perfedion when the body is in health ; and
in many deviations from that ftate we find that its adion is extremely
uncertain and irregular; fometimes rifing higher than the flandard, and
at other times falling much below it. Inftances of this we have in dif-
ferent difeafes, and even in the fame difeafe, within very fhort intervals

N 2 of

of time. A very remarkable one fell under my own obfervation, in a
gentleman who was feized with an apoplectic fit; and while he lay in-
fenfible in bed, covered with blankets, I found that his whole body
would, in an inftant, become extremely cold in every part, continuing
fo for fome time; and, as fuddenly, would become extremely hot. While
this was going on alternately, there was no fenfible alteration in his
pulfe for feveral hours.

Being mafter of the foregoing fad:, that animals had a power of gene-
rating heat, I purfued the fubjeCt ftill further; not fo much with a view
to account for animal heat, as to obferve the different phenomena, with
the variations or difference in different animals. In the courfe of my ex-
periments having found variations in the degree of heat and cold in
the fame experiment, for which I could not account, I fufpeCted that
this might arife from fome imperfection in the confirmation of the ther-
mometer. I mentioned to Mr. Ramfden my objection to the common
conftruCtion of that inftrument, and my ideas of one more perfeCt in its
nature, and better adapted to the experiments in which I was engaged.
He accordingly made me fome very fmall thermometers, fix or feven
inches long, not above two-twelfths of an inch thick in the ftem j having
the external diameter of the ball very little larger than that of the ftem,
on which was marked the freezing point. The ftem was embraced by
a fmall ivory fcale fo as to Hide upon it eafily, and retain any pofition.
Upon the hollow furface of this fcale were marked the degrees which
were feen through the ftem. By thefe means the fize of the thermome-
ter w^ras very much reduced, and it could be applied to foft bodies with
much more eafe and certainty, and in many cafes in which the former
ones could not be conveniently ufed • I therefore repeated with it fuch of
my former experiments as had not at firft proved fatisfaCtory, and found
the degrees of heat very different, not only from what I had expeCted*
but alfb from what I had found by my former experiments with the ther-
mometers of the common conftruCtion.

I have obferved above, and find it fupported by every experiment I
have made on the heat and cold of animals, that the more perfeCt have
the greateft power of retaining a certain degree of heat, which may be

called*

called their Standard heat, and allow of much lefs variation than the more
imperfeCt animals : however, it will appear from the three experiments
which I am now going to relate, that many, if not all of them, are in-
capable of keeping conftantly to one degree; but may be altered from
their Standard heat, either by external applications,, or difeafe. How-
ever, thefe variations are much greater below that Standard than above
it; the perfect animals having a greater power of refiSting heat than coldj,
fo that they are commonly near their ultimate heat. Indeed we do not
want any other proof of a variation than our own feelings : we are all
fenfible of heat and of cold, which lenfations could not be produced
without an alteration really taking place in the parts affeCted; and that
alteration could not take place \'1 f tkey did not becomo actually warmer or
colder. I have often cooled my hands to fuch a degree, that I could
warm them by immerfing them in water juft pumped • therefore my
hands were really colder than the pump-water.

An increafe of abfolute heat muSt alter the texture or pofition of the
paris, fo as to produce the fenfation which we likewife call heat: and as
that heat is diminished, the texture or pofition of the parts is altered in
a contrary way ; and, when carried to a certain degree, becomes the
caufe of the fenfation of cold. Now thefe effects could not take place
in either cafe without an increafe or decreafe of abfolute heat in the part;
heat therefore in its different degrees muSt be prefent. When heat is
applied to the furface of the body, the Skin becomes in fome degree heated
according to the application; which may be carried fo far as actually to
burn the living parts: on the contrary, in a cold atmolphere, a man\'s
hand may become fo cold as to lofe that fenfation altogether, and change
it for pain. Abfolute heat and cold may be carried fo far as even to
alter the Structure of the parts upon which the actions of life depend..

As animals are fubjeCt to variations in their degrees of heat and
cold from external applications, they are of courfe, in this refpe.Ct,. af-
fected in fome meafure like inanimate matter : and therefore,, as parts are
elongated or recede from the common mafs, thefe effeCts more readily
take place: for inftance, all projecting parts, and extremities, more es-
pecially toes, fingers, nofes, ears, combs of fowls, particularly of the

COClC.a^

cock, are more readily cooled, and are therefore moft fubjeft to be affe&ed
by cold. Animals are not only fubjedt to an increafe and decreafe of
heat, fimilar to inanimate matter; but the tranfition from one to the
other (as far as they admit of it) is nearly as quick, I fhall not however
confine myfelf to fenfation alone, as that is in fome degree regulated by
habit: for a habit of uniformity in the application of heat and cold to
an animal body, renders it more fenfible of the fmalleft variation in either
while by the habit of variety it will become, in a proportionable degree,
lefs fufceptible of all fuch fenfations. This is proved every day, in cold
weather, by people who are accuflomed to clothe themfelves warm. In them
the lea ft expofure to cold air, although the effedt produced in the fkin is
perhaps not the hundredth part of a degree, immediately gives the lenfation
of cold, even through the thickeft covering : thofe, on the contrary, who
have been ufed to go thinly clothed, can bear the variation of fome degrees
without being fenfible of it: of this the hands and feet afford an inftance
in point; exciting the fenfation of cold when applied to another part of
the body, without having before given to the mind an impreffion of cold
exifting in them. The projecting parts and the extremities are thofe
which admit of the greateft change in their degrees of heat and cold,
without materially affecting the animal, or even its fenfations.. I find
that by heat or cold externally applied to fuch parts, the thermometer
may, in fome degree, be made to rife or fall; but not in an equal pro-
portion as when applied to inanimate matter. Nor are the living parts
cooled or heated in the fame proportion, as appears from the application
of the thermometer to the fkin; for the cuticle is to be confidered as a
dead covering, capable of receiving greater degrees of heat and cold than
the living parts underneath ; and as it might be fufpefted that the whole
of the variation was,in this covering, to remove any fuch doubt I made
ths following experiments.

Experiment I. I placed the ball of my thermometer under my tongue,
where it was perfe&ly covered by all the furrounding parts ; and having
kept it there for fome minutes, I found that it rofe to 9 f- but this being
.continued, it rofe no higher. I then took feveral pieces of ice, about the
fize of walnuts, and put them in the fame fituation, allowing them only

to

melt in part, that the application of cold might be better kept up, occa-
fionally fpitting out the water arifing from the folution : this I continued
for ten minutes, and found, on introducing my thermometer, that it fell
to 77⁰; fo that the mouth at this part had loft 20° of heat. The ther-
mometer gradually rofe to 97⁰ again ; but did not in this experiment fink
fo low as it would have done in the hand, if a piece of ice had been
held in it for the fame length of time. Perhaps the furface under the
tongue being furrounded with warm parts, renders it next to an impof-
fibility to cool it to any greater degree: but I rather fufpedt that fuch
parts as the hand will allow of greater latitude in this refpedt, from
having infenfibly acquired the habit of varying the degree of cold, and

becoming of courfe lefs fufceptiblc of its ixiipicflluiis.

As a further proof, that the more perfect animals are capable of vary-
ing their heat, in fome meafure, according to the external heat applied,
I fhall adduce the following experiments made on the human fubjedt.

The mouth being a part fo frequently in contact with the external
atmofphere in the adtion of breathing, whatever is put into it may be
fuppofed to be influenced by that atmofphere; this will always render an
experiment made in that part, relative to heat and cold, fomewhat uncer-
tain. I imagined that the urethra would anfwer better, becaufe being an
internal cavity it can only be influenced by heat and cold applied to the
external fkin of the parts. I imagined alfo, that whatever effedts the ap-
plication of heat and cold might have, they would fooner take place in
the urethra, as being a projedting part, than in any other part of the body$
and therefore if living animal matter was in any degree fubjedt to-the
common laws of matter in this refpedt, the urethra would be readily af-
fedted: for this reafon I got a perfon who allowed me to make fuch ex-
periments as I thought neceffary.

Experiment II. I introduced the ball of my thermometer into the
urethra about an inch; after it had remained there about a minute, the
quickfilver rofe only to 92⁰ : at two inches it rofe to 93⁰ * at four inched
the quickfilver rofe to 94⁰ - and when the ball had got as far as the bulb
of the urethra, where it was furrounded by warm parts, the quickfilver
rofe to 97⁰,

Experiment

Experiment III. Thefe parts being immerled for one minute in wafer,
heated only to 65°, and the thermometer introduced about an inch and a
half into the urethra, the quickfilver rofe to 79 : this w^ras repeated feveral
times with the fame fuccefs. As the urethra ftill appeared to be the part
of an animal beft calculated for experiments of this kind ; to find if there
was any difference in the quicknefs of the tranfition of heat and cold in
living and dead parts, and if the extent to which each w^rould go, was
likewife different, I procured a dead penis to make the following com-
parative experiments ; being clearly of opinion that all fuch trials fhould
be as fimilar as poffible, excepting in thofe points where the difference
(if there is any) makes the effential part of the experiment.

Experiment IV. The heat of the penis of a living perfon, an inch
and a half within the urethra, being found exactly 92⁰; and having
heated the dead one to the fame degree, I had both immerfed in the fame
veffel, with the water at 50°, where introducing the thermometers dif-
ferent times, I obferved the comparative quicknefs with which they cooled
from 92⁰. The dead cooled fooner by only two or three degrees. The
living came down to 58°, and the dead to 50". After having continued
the thermometer there lome time longer, it fell no lower. I repeated the
fame experiment feveral times, with the fame fuccefs • although at one
time there might be a fmall difference in the degrees of heat from that of
another, the heat of the water alfo differing; but the difference in thé
refult was nearly proportional in all the three different trials, therefore
the fame conclufions may be drawn from them. In thefe lall: experi-
ments we find very little difference between the cooling of a part of a dead
and of a living body ; but we cannot fuppofe this to take place uniformly
through the whole body, as in that cafe a living man would always be
of the fame degree of heat with the afmofphere in which he lives. The
man not choofing to be cooled lower than 53⁰ or 54% prevented my fee-
ing if the powers of generating heat were exerted in a higher degree
when the heat was brought fo low as to threaten deftruótion ; but by
fome experiments on mice, which will be related hereafter, it will appear-
that the animal powers are roufed to exert themfelves in this refpeCt when
neceffary.

From the experiments related I found, that parts of an animal were
capable of being reduced below the common or natural heat; I therefore
made other experiments, with a view to fee whether the fame parts were
capable of becoming much hotter than the Standard heat of animals.
The experiments were made in the fame manner as the former, only the
water was now hotter than the natural heat of the animal.

Experiment V. The natural heat of the parts being 9 2°, they were
immerfed for two minutes in water heated to 113⁰, and the thermometer
being introduced as before, the quickfilver rofe to 1 oo° and a half. This
experiment I alfo repeated feveral times, but could not raife the heat of
the penis beyond ioo° and a half: this was probably owing to the per-
ion not being able at this time to hear tlie application of water warmer
than 113⁰. As thefe were only fingle experiments, I made a compara-
tive one with the dead part.

Experiment VI. Both the living and dead part being immerfed in
water, gradually made warmer and warmer from ioo° to 118°, and con-
tinued in this heat for fome minutes, the dead part raifed the thermo-
meter to 114⁰, while the living raifed it no higher than 102° and a quar-
ter. It was obferved, by the perfon on whom the experiment was made,
that after the parts had been in the water about a minute, the water did
not feel hot; but on its being agitated it felt fo hot that he could hardly
bear it. Upon applying the thermometer to the fides of the living glans,
the quickfilver immediately fell from 118° to about 104°, while it did
not fall more than a degree when put clofe to the dead; fo that the living
glans cooled the Surrounding water to a certain distance.*

Experiment VII. The heat of the reCtum in the fame man was 98°
and a half exactly.

In the fecond, third, fourth, fifth, and fixth experiments, an internal ¹
cavity, which is both very vafcular and fenfible, was evidently influenced

^a This might furnilh an ufeful hint reflecting bathing in water, whether colder or warmer
than the heat of the body : for if intended to be either colder or hotter, it will fbon be of the
fame temperature with that of the body; therefore in a large bath, the patient fhould move
from place to place 3 and in a fmall one, there fhould be a conftant fucceffion of water of the
intended heat.

O by

by external heat and cold, though only applied to the fkin of the part j
while, in the feventh experiment, another part of the fame body, where
external heat and cold could make little or no impreffion, was of the
ftandard heat. Although it will appear from experiment, that the redtum
is not the warmed part of an animal; yet, in order to determine how far
the heat could be inc-reafed by ftimulating the conflitution to a degree
fufficient to quicken the pulfe, I repeated the feventh experiment after
the man had eaten a hearty fupper and drank a bottle of wine, which in-
creafed the pulfe from 73⁰ to 87% and yet the thermometer only rofe ta
98° and a half.

Having formerly made experiments upon dormice in the fleeping feafon_r
with a view to fee if there was any alteration in the animal ceconomy at
that time, I found among my notes an account of fome experiments,
which appear to our prefent purpofe : but that I might be more certain
of the accuracy of my former experiments, I repeated them with my new
thermometer.

Experiment VIII. In a room, in which the air was at between 50°
and 6o° of temperature, a fmall opening was made in the belly of a dor-
moufe, of a fufficient fize to admit the ball of my thermometr, which
being introduced into the belly at about the middle of that cavity, rofe to?
8o°, and no higher.

Experiment IX. The moufe was put into a cold atmofphere of 15⁰..
above o, and left there for fifteen minutes ; after which the thermometer
being introduced a fecond time, it rofe to 85°.

Experiment X. The moufe was again put into a cold atmofphere
for fifteen minutes ; and the thermometer being again introduced, the
quickfilver rofe to-72⁰ only, but gradually came up to 83°, 84°, and 85°.

Experiment XI. It was put a third time into the cold atmofphere,
and allowed to flay there for thirty minutes j the lower part of the moufe
was at the bottom of the difh, and almoft frozenthe whole of the
animal was numbed, and a good deal weakened. When the thermo-
meter was introduced, the heat varied in different parts of the belly; in
the pelvis, near the parts moft expofed to the cold, it was as low as 62°;

in

in the middle, among the inteftines, about jcp but near the diaphragm
it rofe to 8o°, 82% 84°, and 85° j fo that in the middle of the body the
heat had decreafed io°. Finding a variation in different parts of theTame
cavity in the fame animal, I repeated the fame experiments upon another
dormoufe.

Experiment XII. I took a healthy dormoufe, which had been afleep
from the coldnefs of the atmofphere, and brought it into a room in which
there was a fire (the atmofphere at 64°); I put the thermometer into its
belly, nearly at the middle, between the thorax and pubis, and the
quickfilver rofe to 74⁰ or 75⁰; when I turned the ball towards the dia-
phragm, it rofe to 8o°; and when I applied it to the liver, it rofe to 8i°
and a half.

Experiment XIII. The moufe was put into an atmofphere at 20°,
and left there half an hour; when taken out it was very lively, much
more fo than when put in. I introduced the thermometer into the lower
part of the belly, and it rofe to 91⁰; and upon turning it up to the liver,
to 93⁰.

Experiment XIV. The animal was put back into the cold atmof-
phere at 30⁰ for an hour, when the thermometer was again introduced
into the belly; at the liver it rofe to 93⁰; in the pelvis to 92⁰; it w^ras
{till very lively.

Experiment XV. It was again put back into the cold atmofphere at
19⁰, and left there an hour; the thermometer at the diaphragm was
87°; in the pelvis 83°; but the animal was now lefs lively.

Experiment XVI. It was put into its cage, and two hours after the
thermometer, placed at the diaphragm, was at 93⁰.

As I was unable to procure hedge-hogs in the torpid flate, to afcertain
their heat during that period, I got my friend, Mr. Jenner, furgeon, at
Berkley, to make the fame experiments on that animal, that I might
compare them with thofe in the dormoufe; and his account is as follows.

⁴⁴ Experiment I. In the winter the atmofphere at 44% the heat of a
torpid hedge-hog, in the pelvis, was 45and at the diaphragm 48° and
a half.

O 2 Experiment

Experiment II. The atmofphere 26% the heat of a torpid hedge-hog,
in the cavity of the abdomen, was reduced fo low as 30°.

Experiment III. The hedge-hog was expofed to the cold atmofphere
of 26° for two days j and the heat of the reCtum was found to be 93⁰ .
the wound in the abdomen being now fo fmall that it would not admit
the thermometer.

A comparative experiment was made with a puppy, the atmofphere at
50° -_y the heat in the pelvis, as alfo at the diaphragm, was 102°.

In fummer the atmofphere 78% the heat of the hedge-hog, in an ac~
tive ftate, in the cavity of the abdomen, towards the pelvis, was gf $
at the diaphragm 97⁰."

We find from thefe experiments, that the heat of an animal is increafed
under the circumftances of cold, whenever there are actions to be carried
on for which heat is neceffary.

In the experiments on the firft dormoufe,. the heat of the animal was
8o° which is below the ftandard heat of the actions of that animal; and
after being put into the cold mixture, its heat was raifed to 85°. In
the fecond dormoufe the heat was raifed by repeated experiments from.
75° ^to 93°- A queftion naturally occurs here, was the increafe of heat
owing to the animals being put into a cold atmofphere, and therefore ge-
nerated to refill the cold ? Or was it owing to a wound having been made
into the cavity of the abdomen, which required an exertion of the animal
powers to repair the injury ; and which actions, could not take place
without the necelfary degree of heat ? That it was in confequence of the
wound, appears evident from the experiment made upon the fecond hedge-
hog ; for in an atmofphere of 26° of heat, it was in a very torpid ftate,
and did not raife the thermometer higher than 30°but after being put
back into the cold, and kept there for two days, its heat in the reCtum
was 93⁰; and fo far from being torpid* it was lively, and the bed in
which it lay felt warm.

As this animal allowed its heat to come fo low as 30⁰, when there
was no necelfary a&ion to take place, the increafed heat cannot be at-
tributed to the effedts of cold ; but muft be referred to the wound made
into the belly, that called forth the powers of the animal to repair an

injury which they could not affeCt in a degree of heat below the Standard
heat of the animaland this Stimulus of neceffity for aCtion caufed an
exertion of the powers of generating heat, even in a degree of cold that
would have otherways brought the animal fo low as 30°.

Why the heat of the dormoufe Should be fo low as 8o°, in an atmof-
phere of between 50° and 6o°, is not ealily accounted for, (except upon
the principle of Sleep). But I Should very much SufpeCt, that fleep, fim-
ply confidered, is out of the queftion, as fleep is an effeCt that takes,
place in all degrees of heat and cold. In thofe animals where the volun-
tary aCtions are fufpended by cold, it appears to produce the effeCt by
aCting in a certain degree as a fedative, in confequence of which the ani-
mal faculties are proportionably weakened, but itiil retain, even under
fuch circumftances, the power of carrying on all the functions of life.
Beyond this point cold feems to aCt as a Stimulant, and roufes the animal
powers to aCtion for felf-prefervaticn. It is more than probable, that
moft animals are in this predicament; and that every order has its degree
of cold by which the voluntary actions muft be fufpended.

When a man is afleep, he is colder than when awake; and I find, in
general, that the difference is about one degree and an half, fometimes
lefs. But this difference in the degree of cold between Sleeping and
waking is not a caufe of fleep, but an effeCt; for many diSeaSes produce
a much greater degree of cold in the animal, without giving the leaft
tendency to Sleeptherefore the inactivity of animals from cold is different
from fleep. Befides, all the operations of perfeCt life, as; digeftion, fenfa-
tion, &c_t are going on in the time of natural fleep,. at leaft in the per-
fect animals; but none of thefe operations are performed in the torpid
animals.

To fee how far the refult of thefe- experiments upon dormice was pe-
culiar to them, I wifhed to repeat the fame experiments upon common,
mice; for which purpofe I procured two,, one Strong and vigorous, the
other weakened by faffing.,

Experiment XVII.. The common, atmofphere being at 6o°, I intro-
duced the thermometer into the abdomen of the Strong moufej the ball

being

being at the diaphragm, the quickfilver was raifed to 99®, but at the
pelvis only to 96° and three quarters.

Here there was a real difference of about 9⁰ in two animals of the
fame fize, in fome degree of the fame genus, and at the fame feafon of
the year, and the atmofphere of nearly the fame temperature.

Experiment XVIII. The fame moufe was put into a cold atmofphere
of 13⁰, for an hour, and then the thermometer was introduced as before;
the quickfilver at the diaphragm was raifed to 83°, in the pelvis only
to 78°.

Here the real heat of the animal was diminifhed 16⁰ at the diaphragm,
and 18° in the pelvis.

Experiment XIX. In order to determine whether an animal that is
weakened has the fame powers, with refpedt to preferving heat and
cold, as one that is vigorous and ftrong, I introduced the ball of the
thermometer into the belly of the weak moufe; the ball being at the
diaphragm, the quickfdver rofe to 97S ; in the pelvis to 95⁰ : the moufe
being put into an atmofphere as cold as the other, and the thermometer
again introduced, the quickfilver flood at 79° at the diaphragm, and at
74? in the pelvis.

In this experiment the heat at the diaphragm was diminifhed 18°, in
the pelvis 21?.

Here was a diminution of heat in the fecond greater than in the firft,
we may fuppofe proportional to the decreafed power of the animal, arifing
from want of food.

To determine how far different parts of other animals than thofe
mentioned were of different degrees of heat, I made the following ex-
periments upon a healthy dog.

Experiment XX. The ball of the thermometer being introduced two
inches within the rectum, the quickfilver rofe to ioo° and a half exactly.
The cheft of the dog was then opened, and a wound made into the right
ventricle of the heart, and immediately on the ball being introduced,
the quickfilver rofe to 101⁰ exactly, A wound was next made fome
way into the fubflance of the liver; and the ball being introduced, the
quickfilver rofe to ioo° and three quarters. It was next introduced into

the

the cavity of the ftomach, where it ftood exa&ly at 101 All thefe
experiments were made within a few minutes.

Experiment XXI. The thermometer was introduced into the redtum
of an ox, and the quickfilver rofe exadtly to 99⁰ and a half.

Experiment XXII. This was alfo repeated upon a rabbit, and the
quickfilver rofe to 99⁰ and a half.

From the experiments on mice, and thofe upon the dog, it plainly
appears, that every part of an animal is not of the fame degree of heat •
and hence we may reafonably infer, that the heat of the vital parts of
man is greater than either the mouth, redtum, or the urethra.

To determine how far my idea was juft, that the heat of animals
varied in proportion to thdr impcifc<5livii&, I made die following expe-
riments upon fowls, which I confidered to be one remove below what
are commonly called quadrupeds.

Experiment XXIli I introduced the ball of the thermometer fuc-
ceffively into the inteftinum redtum of feveral hens, and found that the
quickfilver rofe as high as 103°, 103° and a half, and in one of them
to 104°.

Experiment XXIV. I made the fame experiments on feveral cocks,
and the refult was the fame.

Experiment XXV. To determine if the heat of the hen was increafed
when fhe was prepared for incubation,. I repeated the twenty-third ex-
periment upon feveral fitting or clucking hens; in one the quickfilver
rofe to 104° ; in the other to 103° and a half, 103°, as in the twenty-
third experiment.

Experiment XXVI. I placed the ball of the thermometer under the
fame hen, in whofe redtum the quickfilver was raifed to 104, and found
the heat as great as in the redtum.

Experiment XXVII. Having taken fome of the eggs from under the
fame hen, where the chick was about three parts formed, I broke a
hole in the {hell, and introducing the ball of the thermometer, found
that the quickfilver rofe to 99? and a half. In fome that were addled,
I found the heat not fo high by two degrees _; fo that the life in the living
egg affifted in fome degree to fupport its own heat..

It

It may be afked, whether the increafe of three or four degrees of heat,
which is found in the fowl more than in the quadruped, is for the pur-
pole of incubation ? We found that the heat in the eggs, which was
caufed and fupported by the heat of the fowls, was not above the ftandard
of the quadrupeds ; and that it would probably have been lefs, if the heat
of the hen had not been fo great.

Finding from the above experiments, that fowls were fome degrees
warmer than that clafs commonly called quadrupeds (although certainly
lefs perfect animals) I chofe to continue the experiments upon the fame
principle, and made the following upon thofe of a ft ill inferior order.
The next remove from the fowl is thofe commonly called amphibious.

Experiment XXVIII. I took a healthy viper, and introduced the ther-
mometer into its ftomach, and afterwards into its anus; the quickfilver
rofe from 58° (the heat of the atmofphere in which it was) to 68° ; lb
that it was io° warmer than the common atmofphere.

Experiment XXIX. The viper being put into a pan, and the pan
into a cold mixture of about io° ; after remaining there about ten mi-
nutes, its heat was reduced to 37⁰. Being allowed to ftay ten minutes
longer, the mixture at 13⁰, its heat was reduced to 35⁰. It was con-
tinued ten minutes more in the mixture at 20and its heat was reduced
to 31°, nor did it link lower; its tail beginning to freeze; and the ani-
mal now becoming very weak. It may be remarked, that it cooled
much flower than many of the animals mentioned in the following
experiments.

The frog being, in its ftrufture, more fimilar to the viper than to either
the fowl or fifh, I made the following experiments on that animal.

Experiment XXX. I introduced the ball of the thermometer into its
ftomach, and the quickfilver ftood at 44⁰. I then put the frog into a
cold mixture, and the quickfilver funk to 31⁰ ; the animal appeared
almoft dead, but recovered very foon : beyond this point it was not pof-
fible to leffen the heat, without deftroying the animal. But its decreafe
of heat was quicker than in the viper, although the mixture was nearly
the fame.

The next experiments were made on fifties.

Experiment

Experiment XXXI. Having afcertained the heat of the water in a
pond, in which there were carp, to be 65° and a half, I took a carp out
of this water, and introduced the thermometer into its ftomach j the
quickfilver rofe to 69° ; fo that the difference between the water and the
fi£h was only 3⁰ and a half.

Experiment XXXII. In an eel, the heat in the ftomach, which at
firft was at 37⁰, funk, after it had been fome time in the cold mixture,
to 31⁰. The animal at that time appeared dead, but was alive the next
day.

Experiment XXXIIL In a fnail, whofe heat was at 44⁰, it funk,
after it had been put into the cold mixture, to 31°, and then the animal
froze.

Experiment XXXIV. Several leaches having been put into a bottle,
and the bottle immerfed in the cold mixture, the ball of the thermometer
being placed in the middle of them, the quickfilver funk to 31⁰ ; and
by continuing the immerfion for a Sufficient time to deftroy life, the
quickfilver rofe to 32⁰, and then the leaches froze. In all thefe expe-
riments the animals when thawed were found dead.

Finding that the imperfedt claffes of animals will bear to have their
heat reduced to that point at which the folids and fluids freeze when
dead, but if much below it, death muft be the confequence, I wifhed to
determine to what degree of heat the animal could be raifed.

Experiment XXXV. A healthy viper was put into an atmofphere of
108⁰, and allowed to flay feven minutes, when the heat of the animal
in the ftomach and anus was found to be 92⁰ and a half, beyond which
it could not be. raifed in the above heat. The fame experiment was made
upon frogs with nearly the fame refult.

Experiment XXXVI. An eel, very weak, its heat at 44⁰, which was
nearly that of the atmofphere, was put into water heated to 65°, for fif-
teen minutes; and, upon examination, it was of the fame degree of heat
with the water.

Experiment XXXVII. A tench, whofe heat was 41 was put into
water at 65°₉ and left there ten minutes ^ the ball of the thermometer

P being;

being introduced both into the flomach and reClum, the quickfilver rofe
to 55⁰. Thefe experiments were repeated with nearly the fame refult.

To determine whether life had any power of refitting heat and cold
in thefe inferior claffes of animals, I made comparative trials between
living and dead ones.

Experiment XXXVIII. I took a living and a dead tench, and a living
and a dead eel, and put them into warm water; they all received heat
equally fall; and when they were expofed to cold, both the living and
the dead admitted the cold like wife with equal quicknefs.

I had long fufpeCted, that the principle of life was not wholly confined
to animals, or animal fubflance endowed with vifible organization and
fpontaneous motion; but I conceived, that the fame principle exifted in
animal fubftances, devoid of apparent organization and motion, where
the power of prefervation was fimply required.

I was led to this notion twenty years ago, when I was making draw-
ings of the growth of the chick in the procefs of incubation. I then ob-
ferved, that whenever an egg was hatched, the yolk (which is not di-
minifhed in the time of incubation) was always perfectly fweet to the
very lafl; and that part of the albumen, which is not expended on the
growth of the animal, fome days before hatching, was alfo perfectly
fweet, although both were kept in a heat of 103⁰, in the hen\'s egg for
three weeks, and in the duck\'s for four; but I obferved, that if an egg
was not hatched, that egg became putrid in nearly the fame time with
any other dead animal matter.

To determine how far eggs would ftand other tefls of a living principle.*
I made the following experiments.

Experiment XXXIX. Having put an egg into a cold about o, which
froze it, I then allowed it to thaw; from this procefs I imagined that
the preferving powers of the egg muft be deflroyed. I next put this egg
into the cold mixture, and with it one newly laid _} and the difference in
freezing was feven minutes and a half, the frefh one taking fo much
longer time in freezing.

Experiment XL. A new laid egg was put into a cold atmofphere,
fluctuating between 17⁰ and 15⁰ 5 it took above half an hour to freeze;

but

but when thawed and put into an atmofphere at 25⁰, it froze in half
the time. This experiment was repeated feveral times with nearly the
the fame refult.

To determine the comparative heat between a living and a dead egg,,
and alio to determine whether a living egg be fubjedt to the fame laws
with the more imperfedt animals, I made the following experiments.

Experiment XLI. A frefh egg, and one which had been frozen and
thawed, were put into the cold mixture at 15°; the thawed one foon
came to 32⁰, and began to fwell and congeal; the frefh one funk to
29⁰ and a half, and in twenty-five minutes after the dead one, it rofe to
32and began to fwell and freeze.

The refult of this experiment upon the irefM egg was fimilar to the
above experiments upon the frog, eel, fnail, &c. where life allowed the
heat to be diminifhed two or three degrees below the freezing point, and
then refilled all further decreafe; but the powers of life were expended
by this exertion, and then the parts froze like any other dead animal
matter.

From thefe experiments it appears, that a frefh egg has the power of
refitting heat, cold, and putrefaction, in a degree equal to many of the
more imperfedt animals; and it is more than probable^ this power arifes
from the fame principle in both.

From the circumftance of thofe imperfedt animals (upon which I made
my experiments) varying their heat fo readily, we may conclude, that
heat is not fo very effential to life in them as in the more perfect; although
it be effential to many of the operations, or what may be called the fe-
condary actions of life, fuch as digefling food,^a and propagating the fpe-
cies, both which, efpecially the lafl, require the greateft powers an ani-
mal can exert. The animals which we call imperfedt being commonly
employed in the adt of digeftion, we may fuppofe their degree of heat
to be only what that adtion requires ; it not being effentially necef-
fary for the life of the animal that heat fhould ever rife fo high in them.

How far this idea holds good with fifties I am not certain,

P 2

as to call forth the powers neceflary for the propagation of the /pe-
des.⁴

Therefore, whenever thefe imperfect animals are expofed to a cold fo
great as to weaken their powers, and difable them from performing the
fir ft of thefe fecondary actions, they in fome meafure ceafe to be volun-
tary agents, and remain in a torpid ftate during that degree of cold which
always occurs during fome part of the winter in fuch countries as they
inhabit; and the food of fuch animals not being in general produced in
the cold feafon, is a reafon why this torpidity becomes in fome meafure
neceflary.

From this circumftance of the heat of fuch animals being allowed to
link to the freezing point, or fomewhat lower, and then becoming fta-
tionary; and the animal not being able to fupport life in a much greater
degree of cold for any length of time, we fee a reafon why they always
endeavour to procure places of abode in the winter where the cold feldom
links to that point. Thus we find toads burrowing, frogs living under
large ftones, fnails leeking Ihelter under ftones and in holes, and fifties
having recourfe to deep water ; the heat of all which places is generally
above the freezing point in our hardeft frofts ; which however are fome-
times fo fevere, as to kill many whofe habitations are not well chofen.

^a The hedge-hog may be called a truly torpid animal, and we find that its heat is dimlni/hed
when the actions are not vigorous. From a general review of this whole fubject it would
appear, that a certain degree of heat in the animal is neceflary for its various ceconomical
operations, among which is digeftion ; and that neceflary heat will be according to the nature
of the animal, and probably the nature of the neceflary operations to be performed. A frog
will digeft food when its heat is at 6o°, but not when at 35⁰ or 40? ; and it is very probable
that, when the heat of the bear, hedge-hog, dormoufe, bat, &c. is reduced to 70°, 75⁰, or
8o°, they lofe their power of digeftion; or rather that the body, in fuch a degree of cold, has
no call upon the ftomach. That animals, in a certain degree of heat, muft always have
food, is further illuftrated by the inftance of bees. The conftru&ion of a bee is very fimilar
to a fly, a wafp, &c. A fly and a wafp can allow their heat to diminifh as in the fifh, fnake,
&c. without lofing life, but a bee cannot; therefore a bee is obliged to keep up its heat as
high as what we call its digeftive heat, but not its propagating-; for which purpofe they pro-
vide againft fuch cold as would deprive them even of their digeftive heat, if they had not food
to preferve it.

When

When the frofl is more intenfe and of longer (landing than common,
or in countries where the winters are always fevere, there is generally
fnow, and the water freezes: the advantage arifmg from thefe two cir-
cumstances are great; the fnow ferving as a blanket to the earth, and
the ice to the water.¹

As all the experiments I ever made upon the freezing of animals,
with a view to fee if it were poffible to reflore the actions of life when
thawed, were made upon whole ones, and as I never faw life return by
thawing," I wifhed to fee how far parts were Similar to the whole in
this refpedt; efpecially as it is afferted, and with fome authority, that
parts of a man may be frozen, and afterwards recover: for this purpoie
I made the following experiments upon an animal of the fame order as
ourfelves.

In January 1777, I mixed fait and ice till the cold was about o ; on
the fide of the veffel was a hole, through which I introduced the ear of
a rabbit. To carry off the heat as fail as poffible, it was held between
two flat pieces of iron that went further into the mixture. That part

1 It would be worthy of the attention of the philofopher, to inveftigate the caufe of the heat
of the earth, upon what principle it is preferved, &c.

Vide Phil. Tranf. for the year 1775, vol. LXV. part II. p. 446.

Of

of the ear projecting into the veffel became ftiff, and when cut did not
bleed ; and the part cut off by a pair of fciffars, flew from between the
blades like a hard chip.

The ear remained in the mixture nearly an hour: when taken out it
foon thawed, and began to bleed, and became very flaccid, fo as to dou-
ble upon itfelf, having loft its natural elafticity. When out of the
mixture nearly an hour, it became warm, and this warmth increafed to
a confiderable degree, and alfo began to thicken, in confequence of in-
flammation, while the other ear continued in its ufual cold. The day
following the frozen ear was ftill warm ; and two days after it retained
its heat and thicknefs, which continued for many days after.

About a week after this, the mixture being the fame as the former, I
introduced both ears of the fame rabbit through the hole, and froze them
both: the found one however froze firft, probably from its being confi-
derably colder at the beginning. When withdrawn they foon thawed,
and both foon became warm, and the frefh ear thickened as the other
had done before.

Thefe changes in the parts do not always fo quickly take place j for on
repeating thefe experiments on the ear of another rabbit till it became as hard
as a board, it was longer in thawing than in the former experiment, and
much longer before it became warm; however in about two hours it be--
came a little warm, and the day following it was very warm and thickened.

In the fpring 1776, I obferved that the cocks I had in the country
had their combs fmooth with an even edge, and not fo broad as formerly,
appearing as if near one half of them had been cut off. Having inquired
into the caufe of this, my fervant told me, that it had been common
in that winter during the hard froft. He obferved, that they had become
in part dead, and at laft dropped off: alfo, that the comb of one cock
had dropped entirely off; this I did not fee, as by accident he burnt him-
felf to death. I naturally imputed this effeCt to the combs having been
frozen in the time of the fevere froft; and having, confequently, loft the
life of that part by this, operation. I endeavoured to try the folidity of
this reafoning by experiment.

I attempted-

I attempted to freeze the comb of a very large young cock (which
was of a confiderable breadth) but could only freeze the ferrated edges
(which proceffes were full half an inch long) ; the comb itfelf being very
thick and warm refilled the cold. The frozen parts became white and
hard j and when I cut off a little bit it did not bleed, nor did the ani-
mal fhow any figns of pain. I next introduced into the cold mixture
one of his wattles, which was very broad and thin; it froze very readily:
upon thawing both the comb and wattle, they became warm, but were
of a purple colour, having loft the tranfparency which remained in the
other parts of the comb and in the other wattle. The wound in the
comb now bled freely.

Both comb and wattle recovered perfectly "in about a month. The
natural colour returned firft neareft to the found parts, increafing gra-
dually till the whole had acquired a healthy appearance.

There was a very material difference in the effeCt between thofe fowls,
the ferrated edges of whofe combs I fufpeCted to have been frozen in the
winter of 1765-6, for they muft have dropped off. The only way in
which I can account for this difference is, that in thofe fowls the parts
were kept fo long frozen, that the unfrozen or aCtive parts had time to
inflame, and had brought about a feparation of the frozen parts, treating
them exactly as dead, limilar to a mortified part; and that before they
thawed, the feparation was fo far compleated as to deprive them of further
fupport.

As it is confidently afferted, that fifties are often frozen and come to life
again, and as I had never fucceeded in any of my experiments of this
kind upon whole fifties, I made fome partial experiments upon this clafs
of animals being led to do this by having found a material difference in
the refult of the experiments made upon the whole animal, and of thofe
made only on parts of the more perfeCt animals.

I froze the tail of a tench (as high as the anus) which became as hard
as a board; when it thawed, that part was whiter than common; and
when it moved, the whole tail moved as one piece, and the termination
of the frozen part appeared like the joint on which it moved.

Oft

On the fame day I froze the tails of two gold fiihes till they became as
folid as a piece of wood. They were put into cold water to thaw, and
appeared for fome days to be very well; but that part of the tails which
had been frozen had not the natural colour, and the fins of the tails be-
came ragged. About three weeks after a fur came all over the frozen
parts ; their tails became lighter, fo that the fifhes were fufpended in the
water perpendicularly, and they had almoft loft the power of motion ;
at laft they died. The water in which they were kept was New River
water, fhifted every day, and about ten gallons in quantity.

I made fimilar experiments upon an order of animals ftill inferior, viz.
common earth-worms.

I firft froze the whole of an earth-worm as a ftandard; when thawed
it was perfectly dead.

I then froze the anterior half of another earth-worm j but the whole
died.

I next froze the pofterior half of an earth-worm; the anterior half
lived, and feparated itfelf from the dead part.

From fome of thefe experiments it appears, that the more imperfeCt
animals are capable of having their heat and cold varied very confiderably,
but not according to the degree of heat or cold of the furrounding me-
dium in which they can fupport life; for they can live in a cold con-
fiderably below the freezing point, and yet the living powers of the ani-
mal will not allow their heat to be diminifhed much beyond 3 2° ; and
whenever the furrounding cold brings them fo low, the power of genera-
ting heat takes placej and if the cold is continued, the animals exert
this power till life is deftroyed ; after which they freeze, and are imme-
diately capable of admitting any degree of cold.

EXPLANATION

C ^SI3 1

explanation of the plate,

A Thermometer which has the fcale fo conftrudted as to admit of
its being introduced into any cavity that can receive the ball. The:
fcale is moveable $ but the freezing point is marked on the ftem or glafs*

Figure I. A front view, expofing the glafs ftem of the thermome-
ter, through which the divifions marked upon the concave furface of the
Aiding ivory fcale which embraces it, are very diftin&ly feen.

a The freezing pointy which iff marked upon tk© ftcm hy a fLicUCÏl Oil
the glafs.

«

Figure II. A fide view, Showing the degrees marked near the edge:
of the convex fide of the ivory fcale.

The thermometer is to be adj ufted for meafuring high or low degrees
of heat, by bringing any number marked upon the fcale oppofite the:
freezing point* and counting either upwards or downwards.

PROPOSALS

C "5 3

PROPOSALS FOR THE RECOVERY OF PERSONS
APPARENTLY DROWNED.

HAVING been requeued by a principal member of the fociety
eftablifhed for the recovery of perfons apparently drowned, to com-
mit my thoughts on that fubjeCt to paper, I readily complied with his
requeft, hoping, that although I have had no opportunities of making-
aCtual experiments upon drowned perfons, it might be in my power to
throw fome lights on a fubjeCt fo clofely connected with the inquiries
which, for many years, have been my favourite bufinefs and amufement.
I therefore collected together my oblervations and experiments relative to
the lofs and recovery of the actions of life, which I now offer to the
public. The practice is new, and has furnifhed as yet few important
and clear facts. If we judge of the queftion by our general knowledge of
the animal œconomy, I am afraid that it is fo imperfectly understood,
that our reafoning from it alone cannot be relied on : neverthelefs, on a
fubjeCt fo interefting to humanity, we mufl not be idle ; we muft throw
out our obfervations, and reafon as well as we can from the few data we
have, in hopes that the fubjeCt, thus put fairly into the hands of the
public, may in time, by their united endeavours, become perfectly un-
derftood.

I fhall confider an animal, apparently drowned, as not dead ; but
that only a fufpenfion of the aCtions of life has taken place/ This,

³ The différence between a fufpenfion of the actions of life, and abfolute death, is well
Llluftratcd by the common fnail when drowning. If a fnail is immerfcd in water and kept
there, certain voluntary and inftinftive actions take place ; but after , remaining a certain
time covered by the water, all thefe anions ceafe -, the animal becomes relaxed, in which
ftate it naturally comes out of the ftiell, and the body appears large, giving the full fize of the
animal, but without any motion ; all its actions being fufpended, and continue to be fo till
either the caufe of the fufpenfion is removed, or fome other ftimulus fhall bring the parts into
aftion ; but in this ftate life cannot be preferved for any confiderable length of time ; and
when the ftimulus of death takes place, the whole animal is thrown into action, in which con-
traded ftate abfolute death is produced. A ftate of relaxation Ihould therefore (in cafes where
an univerfal violence has not been committed) be confidered as a criterion of life ; and even
in them it ihould be for fome time admitted as a probable reafon for fuppofing life ftill toexift.

a probably

probably, is the cafe in the beginning of all violent deaths, except
thofe caufed by lightning, electricity, an univerfal (Lock, by which ab-
folute death may be inflantaneoufly produced; or a blow on the ftomach
which appears to aft in the fame way, producing abfolute death im-
mediately : for in all thofe cafes which have fallen under my obferva-
tion, the concomitant circumftances have refembled thofe which attend
death caufed by lightning or electricity; fuch as a total and inftan-
taneous privation of fenfe and motion without convulfions, confequently
without any rigor of mufcles; and the blood remaining uncoagulated;
differing entirely in thefe refpeCts from what appears in perfons deprived
of fenfe and life by any injury done the brain, It feems only poffible
to account for this effedt of a blow on the ftomach, from the con-
nection fubfifting between this vifcus and every part of the body, at leaft
with vital parts ; the blow mofl probably producing inflant death in that
organ, in confequence of which the whole animal dies/

That I may more fully explain my ideas upon this fubjedt, it will be
neceffary to flate fome proportions.

Firft, that fo long as the animal retains the powers, though deprived
of the action of life, the caufe of that privation may frequently be re-
moved ; but, when the powers of life are deftroyed, the adtion ceafes to
be recoverable. Secondly, it is neceffary to mention that I confider part
of the living principle as inherent in the blood.^b The lafl propofition I
have to eftablifh is, that the ftomach lympathizes with every part of an

³ I fhould confider the fituation of a perfon drowned to be fimilar to that of a perfon in a
trance. In both the action of life is fufpended, without the power being deftroyed; but I am
inclined to believe, that a greater proportion of perfons recover from trances than from drown-
ing ; becaufe a trance is the natural effeft of a difpofition in the perfon to have the action of
life fufpended for a time; but drowning being produced by violence, the fufpenfion will more
frequently laft for ever, unlefs the power of life is roufed to action by fome applications of art.

^b That the living principle is inherent in the blood, is a do&rine which the nature of this
account will not allow me to difcufs : thus much however it may be proper to fay, that it is
founded on the refults of many obfervations and experiments. But it may be thought necef-
fary here to give a definition of what I call the living principle : fo far as I have ufed the term,
I mean to exprefs that principle which preferves the body from difTolution with or without
aftion, and is the caufe of all its actions.

animal,

animal, and that every part lympathizes with the ftomach_; therefore,
whatever adts upon the ftomach as a cordial, or roufes its natural and
healthy a&ions, and whatever affedts it, fo as to produce debility, has an
immediate effedt upon every part of the body. This fympathy is ftrongeft
with the vital parts. Befides this univerfal fympathy between the fto~
mach and all parts of the body, there are peculiar fym£>athies j for in-
ftance, the heart fympathizes immediately with the lungs. If any thing
is received into the lungs, which is a poifon to animal life, fuch as in-
flammable air, volatile vitriolic acid, and many other well known fub-
ftances, the motion of the heart immediately ceafes, much fooner than if
the trachea had been tied j and from experiments it appears, that any
thing falutary to life, applied to the lungs, will reitore the heart\'s a&ion
after it has been at reft fome time.

I lhall divide violent deaths into three kinds. Firft, where a ftop is
only put to the a£tion of life in the animal, but without any irreparable
injury to a vital part; which aftion, if not reftored in a certain time,
will be irrecoverably loft. The length of that time is fubjedt to conli-
derable variation, probably depending on circumftances with which we
are at prefent unacquainted. The fecond is, where an injury is dofte to
a vit^l part as by taking away blood till the powers of action are loft ;
or by a wound or prefture on the brain or fpinal marrow, fufficient life
remaining in the folids, if actions could be reftored to the vital parts „
The third is, where abfolute death inftantly takes place in every part, as
is often the cafe in ftrokes of lightning; in the common method of kill-
ing eels, by throwing them on fome hard fubftance, in fuch manner as
that the whole length of the animal fhall receive the fhock at the fame
inftant; and, as I believe, happens by a blow on the ftomach; in all
which cafes the mufcles remain flexible.⁸

How far that may be ftridtly confidered as a violent death, which is
caufed by affections of the mind, I will not pretend to fay; but if it is to

^a On the other hand, when an eel is killed by chopping it into a number of pieces, the
powers of life are by thofe means roufed into adlion; and, as every part dies in that a&ive
ft ate, every part is found ft iff after death. This explains the cuftom of cutting fifh into
pieces while vet alive, in order to make them hard, ufually known by the name of crimping.

have

have a place in that clafs, it muft be ranked with thofe which happen
from lightning, and a blow on the Stomach : and in moft cafes of perfons
drowned, I can eafily conceive the mind to be fo much affedted, prior to
the immerfion and in the moment immediately fucceeding it, as to make
a material difference in the power of recovery.

The prefent confideration is, which of the kinds of violent death
drowning comes under ? I fuppofe it moll commonly comes under the
fir ft; and upon that ground I fhall principally confider the fubjedt.

The lofs of motion in drowning feems to arife from the lofs of ref-
piration, and the immediate effedts which this has upon the other vital
motions of the animal : except what may have arifen from the affedtions
of the mind ; however, the privation of breathing appears to be the firfl
caufe; and the heart\'s motion ceafing, to be the fecond or confequent;
therefore moft probably the reftoration of breathing is all that is neceffary
to reftore the heart\'s motion: for if a Sufficiency of life Still exifts to
produce that effedt, we may fuppofe every part equally ready to move the
very inftant in which the adtion of the heart takes place, their adtions
depending fo much upon it. What makes it very probable, that in re-
covering perfons drowned, the principle effedt depends upon air being
thrown into the lungs, is, what happens in the birth of children, when
too much time has been fpent after the interruption of that life which is
peculiar to the foetus; they then lofe altogether the difpofition for the
new life; and in fuch cafes there being a total fufpenfion of the adtions
of life, the child remains to all appearance dead, and would die, if air
were not thrown into its lungs, and by this means the firSl principle of
adtion reSlored. To put this in a ftill clearer light, I will give the refult
of fome experiments which I made in the year 1755 upon a dog.

A pair of double bellows were provided, conftrudted in fuch a manner
as by one adtion to throw frefh air into the lungs, and by another to
fuck out again the air which had been thrown in by the former, without
mixing them together. The muzzle of thefe bellows was fixed into the
trachea of a dog, and by working them he was kept perfedtly alive.
While this artificial breathing was going on, I took off the Sternum of
the dog, and expofed the lungs and heart 5 the heart continued to adt as

before,

before, only the frequency of its aCtion was confiderably increafed. I
then flopped the motion of the bellows, and the heart became gradually
weaker and lefs frequent in its contraction, till it left off moving alto-
gether : by renewing my operation, the heart begun again to move, at
firfl very faintly, and with longer intermifllons; but by continuing the
artificial breathing its motion became as frequent and as ftrong as before»
This procefs I repeated upon the fame dog ten times, fometimes flopping
for five, eight, or ten minutes. I obferved that every time I left off
working the bellows, the heart became extremely turgid with blood, and
the blood in the left fide became as dark as that in the right; which
was not the cafe when the bellows were working. Thefe fituations of
the animal appear to me exactly limilar 10 drowning.

The lofs of life in drowned perfons has been accounted for, by fuppo-
fing that the blood rendered unfit by want of the aCtion of the air in re-
lpiration, is fent in that vitiated fiate to the brain and other vital parts»
by which means the nerves lofe their effeCt upon the heart, and the heart
in confequence its motion. This however I am fully convinced is falfe :
firfl, from the experiments on the dog, in whofe cafe a large column of
bad blood, viz. all that was contained in the heart and pulmonary veins
was pufhed forward without any ill effeCt being produced; and next, from
the recovery of drowned perfons and ftill-born children, which, under
fuch circumftances, never could happen, unlefs a change of the blood
could take place in the brain, prior to the refloration of the heart\'s mo-
tion : thefore the heart\'s motion mufl depend immediately upon the ap-
plication of fuch air to the lungs, and not upon the effeCts which air has
upon the blood, and which that blood has upon the vital parts. Thefe
are only fecondary operations in the animal ceconomy. However, if the
affeCtions of the mind have had any fhare in the ceffation of aCtions in the
heart, that will not be fo eafily reftored as it would otherwife be : therefore
in our attempts to recover perfons drowned, it might be proper to inquire
if there had been time fufficient for the perfon to form any idea of his
fituation, previous to his being plunged into the water. It is more than
probable, in fuch a cafe, that the agitated ftate of mind might aflift in
killing him; and I fhould very much doubt the probability of recovering

fuch

fiich a perfon. In the hiftory of thofe who have, and who have not been
recovered, could the difference be afligned to any fuch caufe, it might
lead to fomething ufeful.

It frequently happens in the cafe of drowning, that affiftance cannot be
procured till a confiderable time after the accident; every moment of
which delay renders recovery more precarious, the chances of which are
not only diminifhed in the parts where the firft powers of aCtion princi-
pally refide, but alfo in every other part of the body.

In offering my fentiments on the method of treating perfons who are
apparently drowned, I fhall fay firft, what I would recommend to have
done; fecondly, what I would wifh might be avoided.

When affiftance is called in, i\'oon after the immerfion, perhaps blow-
ing air into the lungs may be Sufficient to effect a recovery/ But if a
confiderable time, fuch as an hour, has been loft, this will feldom be
fufficient; the heart, in all probability, having by this time loft its nice
connection with the lungs. It will therefore be proper to apply fuch
Stimulating medicines, as the vapour of volatile alkali, mixed with the
air _; which may eafily be done, by holding fpirits of hartfhorn in a cup
under the receiver of the bellows. I w^Tould advife the air and volatile
alkali to be thrown in by the nofe, rather than the mouth, as the lafl
mode of adminiftering, by producing ficknefs, is more likely to deprefs
than roufe the living principle. It will be ftill better if it can be done by
both noftrils, as applications of this kind to the olfaCtory nerves are
known to roufe the living principle and put the mufcles of refpiration into
adtion, and are therefore likely to excite the aCtion of the heart: Befides
affeCtions of thefe nerves more immediately affeCt the living principle, for
while a ftrong fmell of very fweet flowers, as orange flowers, fhall in many
caufe fainting, the application of vinegar will immediately reftore the
powers to aCtion again. All perfumes in which there is fome acid, rather
roufes than depreffes, as the fweet-brier, eifence of lemon, &c. If during

^a Perhaps the dephlogifticated air, defcribed by Dr. Prieftley, may prove more efficacious
than common air. It is eafily procured, and may be preferved in bottles or bladders for that
purpofe.

the

the operation of the bellows, the larynx be gently prefied againft the
cefophagus and fpine, it will prevent the Stomach and inteftines being too
much diftended by the air, and leave room for the application of more
effectual Stimuli to thofe parts. This preffure however muft be conducted
with judgment and caution, fo that the trachea and the aperture into the
larynx may both be left perfectly free. While this bufinefs is going on,
an affiftant Should prepare bed-deaths, carefully brought to the proper
degree of heat. I confider heat as congenial with the living principle;
increafing the neceffity of adtion it increafes adtion : cold, on the other
hand, leffens the neceffity, and of courfe the adtion is diminished; to a
due proportion of heat, therefore the living principle owes its vigour.

From obfervations and experiments it appears to he a law of nature in
animal bodies, that the degree of external heat Should bear a propor-
tion to the quantity of life; as it is weakened, this proportion requires
great accuracy in the adjuftment ; while greater powers of life allow^r it
greater latitudes/

I was led to make thefe obfervations by attending to perfons who are
froft-bitten ; the effedt of cold in this cafe being that of leffening the living
principle. The powers of adtion remain as perfedt as ever, only weakened;
and heat is the only thing wanting to put thefe powers into adtion ; yet
heat muft at firit be gradually applied, and proportioned to the quantity of
the living principle; but as that increafes you may increafe the degree of
heat. If this method is not obferved, and too great a degree of heat is
at firft applied, the perfon or part lofes entirely the living principle, and
mortification enfues. This procefs invariably takes place with regard to
men. The fame thing, I am convinced, happens to other animals. If
an eel, for inftance, is expofed to a degree of cold Sufficiently intenfe to
benumb it till the remains of life are fcarcely perceptible, and ftill re-
tained in a cold of about 40⁰ ; this fmall proportion of living principle
. will continue for a considerable time without diminution or increafe; but

^a It is upon thefe principles that cold air is found of fo much fervice to people who are
reduced by difeafe, as the confluent fmallpox, and fevers, by diminishing heat in proportion to
the diminution of life ; or lefieaing the neceffity of the body\'s producing its own cold.

R if

if the animal is afterwards placed in a heat about 60 after fhowing
ftrong figns of returning life, it will die in a few minutes. Nor is this
circumftance peculiar to the diminution of life by cold. The fame phe-
nomena take place in animals who have been very much reduced by
hunger.

If a lizard, or fnake, when it goes to its autumnal hiding place, is not
fufficiently fat, the living powers become, before the feafon permits it
to come out, very confiderably weakened, perhaps fo much as not to be
again reftored. If animals, in fuch a ftate, are expofed to the fun\'s rays,
or placed in any fituation which by its warmth would give vigour to
thofe of the fame kind, poftefled of a larger fhare of life, they will im-
mediately ihow figns of increafed life, but quickly fink under the experi-
ment and die; while others, reduced to the fame degree of weaknefs, as
far as appearances can difcover, will live for many weeks, if kept in a
degree of cold proportioned to the quantity of life they poftefs.

I obferved many years ago, in fome of the colder parts of this illand,
that when intenfe cold had forced blackbirds or thrufhes to take fhelter in
out-houfes, any of them that had been caught, and from an ill-judged
companion expofed to a confiderable degree of warmth, died very foon.
The reafon of this I did not then underftand but I am now fatisfied
that it was owing, as in other inftances, to the degree of heat being in-
creafed too fuddenly for the proportion of life remaining in the animal.

From thefe fadts it appears, that warmth caufes a greater exertion of
the living powers than cold; and that an animal in a weakly ftate may
be obliged by it to exert a quantity of the adtion of life fufRcient to deftroy
the very powers themfelves.^a The fame effedts probably take place even
in perfedt health. It appears from experiments made in a heated room,
that a perfon in health, expofed to a great degree of heat, found the ac-
tions of life accelerated fo much as to produce at laft faintnefs and debility .^b

If bed-cloaths are put over the drowned perfon fo as fcarce to touch
him. fteam of volatile alkali, or of warm balfams and elfential oils, may

^a It is upon this principle that parts mortify in confequence of inflammation.

* Vide Phil. Tranf. for the year 1775, vol. 65. p.. in..

be

be thrown under fo as to come in contact with many parts of his body.
It will certainly prove advantageous if the fame fleams can be conveyed
into the llomach, as that feat of univerfal fympathy will be roufed by fuch
means. This may be done by a hollow bougie and a fyringe ; but the
operation fhould be performed with all poffible expedition, becaufe the
inftrument, by continuing in the mouth, may produce ficknefs, an effedt
I fhould chufe to avoid. Some of the ftimulating fubflances, which are
of a warm nature, and have an immediate effedt, may be thrown into the
ftomach in a fluid ftate, viz. as fpirits of hartfhorn, peppermint-water,
juice of horfe-raddifh, and many others which produce a more lafting
ftimulus, as balfams and turpentines, which are found to quicken the
pulfe of a man in health ; but the quantity muft he fmall, ay they have
a tendency to produce ficknefs. The fame fleam and fubflances fhould
alfo be thrown up by the anus. The procefs recommended under the
firfl head of treatment fhould flill be continued, while that recommended
under the fecond is putting in practice, as the lafl is only an auxiliary to
the firfl. The firfl, in many cafes, may fucceed alone; but the fecond
without the firfl muft, I think, always fail where the powers of life are
confiderably weakened. Motion may poftibly be of fervice, it may at
leaft be tried; but, as it has lefs effedt than any other of the ufually pre-
fcribed ftimuli, it fhould be the lafl part of the procefs.^a I would recom-
mend to the operator the fame care in regulating the proportion of every
one of thefe methods, as I did before in the application of heat; as every
one of them may poflibly have the fame property of entirely deftroying
the feeble action which they have excited, if adminiftered in too great a
quantity; inftead therefore of increasing and haftening the operations on
the firfl figns of returning life being obferved, as is ufually done, I fhould
with them to be leffened, that their increafe afterwards may be directed,

^a Electricity has been known to be of fervice, and fhould be tried when other methods
have failed. It is probably the only method we have of immediately ftimulating the heart;
all other methods being more by fympathy. I have not mentioned injecting ftimulating fub-
flances direftly into the veins, though it might be fuppofed a proper expedient; becaufe, in
looking over my experiments on that fubject, I found none where animal life received increafe
by that method.

R 2 as

as nearly as poflible, by the quantity of powers as they arife. As the
heart is commonly the laft part that ceafes to aft, it is probably the firft
part that takes on the adtion of recovery. When it begins to move, I
would advife leffening the application of air to the lungs, and enjoin ob-
ferving with great attention when the mufcles of refpiration begin to adt,
that our endeavours may not interfere with their natural exertions ; yet
that we may be ftill ready to aflift. I would by all means difcourage
blood-letting; which I think weakens the animal principle, and life itfelf,
confequently leffens both the powers and difpofitions to action : and I
would advife to be careful not to call forth any dilpofition that might
deprefs, by introducing any thing into the ftomach, which ordinarily cre-
ates naufea, as that alfo will have a fimilar effedt, except it can be carried
fo far as to relieve itfelf by exciting vomiting, and would therefore avoid
throwing any thing in by the anus which is likely to produce an evacu-
ation that way, as every fuch evacuation alfo tends to leflen the animal
powers : I have purpofely avoided fpeaking of the fumes of tobacco*
which always produce ficknefs or purging, according as they are applied.

Whoever is appointed for the purpofes of recovering drowned perfons,
Should have an affiftant, well acquainted with the methods intended to
be made ufe of; that while the one is going on with the firft and moll
fimple methods, the other may be preparing what elfe may be neceiTary,
fo that no time may be loft between the operations; and the more fo, as
the firft means recommended, will, in all cafes, afiift the fecond, and both
together may often be attended with fuccefs, though each feparately might
have failed.

A proper apparatus is alfo eflentially neceftary to the inftitution, a de-
fcription of which I here annex. Firft, a pair of bellows, fo contrived
with two feparate cavities, that by expanding them, when applied to
the noftrils or mouth of a patient, one cavity may be filled with the
common air, and the other with air fucked out from the lungs ; and by
Shutting them again, the common air may be thrown into the lungs, and
that which is fucked out of the lungs be difcharged into the room. The
pipe of thefe Should be flexible, in length a foot or a foot and a half, and
at leaft three-eighths of an inch in width; by this the artificial breathing

may

may be continued, while the other operations, except the application of
the ftimuli to the ftojmach, are going on, which cannot conveniently be
done if the muzzle of the bellows be introduced into the nofe. The end
next the nofe Ihould be double, and applied to both noftrils. Secondly,
a fyringe, with a hollow bougie, or flexible catheter, of fufficient length
to go into the ftomach, and convey any Simulating matter into it, with-
out affedting the lungs. Thirdly, a pair of fmall bellows, fuch as are
commonly ufed in throwing fumes of tobacco up the anus, by which
Simulating fluids, or even fumes may be thrown in.

I {hall conclude this account by propofmg, that all who are employed
In this practice be particularly required to keep an accurate journal of the
means ufed, and the degree of fuccefs attending them 5 whence we may
be furnifhed with fadts fufficient to enable us to draw conclufions, on
which a certain pradtice may hereafter be eftablifhed*

ON

ON THE STRUCTURE OF THE PLACENTA,

jeCt, has in every age, in which fcience has been cultivated, called
forth the attention of the anatomift, the phyfiologift, and even the phi-
lofopher •> but both that connection, and the itruCture of the parts which
form the connection, were unknown until about the year 1754. The
fubjeCt is certainly moft interefting, and the difcovery important; and it
is my intention, in the following pages, to give fuch an account of it as
I hope may be acceptable to the public while, at the fame time, I
eftablifh my own claim to the difcovery. But that I may not feem to
arrogate to myfelf more merit than I am entitled to, .let me, in jultice
to another perfon, relate what follows.

The late indefatigable Dr. Mc. Kenzie, about the month of May
1754, when affiltant to Dr. Smellie, having procured the body of a
pregnant woman, who had died undelivered at the full term, had injeCted
both the veins and arteries with particular fuccefs; the veins being filled
with yellow, the arteries with red.^b

Having opened the abdomen, and expofed the uterus ; he made an in-
eifion into the fore part, quite through its fubfiance, and came to fome-
what having the appearance of an irregular mafs of injeCted matter,
which afterwards proved to be the placenta. This.appearance being new,
he flopped, and greatly obliged me, by defiring my attendance to examine
the parts, in which there appeared fomething lo uncommon. This ex-
amination was made in his. prefence, and in the prefence of feveral other

^a This paper was read at the Royal Society; hut as the fails had, before that, time, been
given to the public, it was not publifhed in the Philofophical Transactions.

^b Dr. Mc. Kenzie being then an affiftant to the late Dr. Smellie, his procuring and di,Test-
ing\' this woman, without Dr.. Smellie\'s knowledge, was the caufe of a .feparation between
them : for the leading fteps to fuch a difcovery could not be kept a fee ret. The winter fol-
lowing, Dr. M.c. Kenzie began to teach, midwifery in the Borough of Southwark.

gentlemen

gentlemen whole names I have now forgotten; but I have reafon to
believe that fome are fettled in this country, and I hope will have an
opportunity of perufing this publication/

I firft raifed, with great care, part of the uterus from the irregular
mafs above mentioned; in doing which I obferved regular pieces of wax
paffing obliquely between it and the uterus, which broke off, leaving part
upon this mafs ; and when they were attentively examined, towards the
uterus, plainly appeared to be a continuation of the veins paffing from it
to this fubftance or placenta.

I likewife obferved other veffels, about the fize of a crow-quill, paffing
in the fame manner, although not fo obliquely ; thefe alfo broke upon
feparating the placenta and uterus, leaving a fmall portion on the furface
of the placenta and on examination they were difcovered to be contin-
uations of the arteries of the uterus. My next ftep was to trace thefe
veffels into the fubftance of what appeared placenta, which I firft at-
tempted in a vein ; but that foon loft the regularity of a veffel, by termi-
nating at once upon the furface of the placenta in a very fine fpongy fub-
ftance the interftices of which were filled with the yellow injected
matter. This termination being new, I repeated the fame kind of exa-
mination on other veins, which always led me to the fame terminations,
never entering the fubftance of the placenta in the form of a veffel. I

^a If I fhould be fo fortunate as to have this publication fall into any of thofe gentlemens
hands, I hope they will favour me with their opinion of my ftate of the facts, which led to
the difcovery.

It may be fufpected by fome, (but none I hope to whom I have the pleafure of beinc;
known) that I am not doing Dr. Mc. Kenzie juftice, and am perhaps fuppreffing fome part
of that fhare of the difcovery to which he is entitled. This idea, (if ever it ftiould arife) I
may probably not be able to remove; but I hope it will alfo be feen, that I myfelf have given
rife to it; believing, if I had been fo inclined, that I might have fupprefled Dr. Mc. Kenzie\'s
name altogether, without ever running the hazard of being detected. I was indeed fo tena-
cious of my claim to the difcovery, that I wrote this account in Dr. Mc. Kenzie\'s life-time,
with a defign to publiih it; and often communicated my intentions to Dr. George Fordyce,
who I knew was very intimate with the Doctor, in confequence of both teaching in the fame
place, and making many experiments together 3 therefore he is a kind of collateral witne%
that what I now publifh is the fame account which I gave in Dr. Mc. Kenzie\'s life-time.

next

next examined the arteries, and tracing them in the fame manner toward
the placenta, found that they made a twift, or dole fpiral turn upon
themfelves, and then were loft on its furface. On a more attentive view, I
perceived that they terminated in the fame way as the veins; for oppofite
to the mouth of the artery, the fpongy fubftance of the placenta was
readily obferved, and was intermixed with the red injection.

Upon cutting into the placenta, I difcovered in many places of its
fubftance, yellow injection _; in others red, and in many others theie two
colours mixed. This fubftance of the placenta, now filled with injec-
tion, had nothing of the vafcular appearance, nor that of extravafation,
but had a regularity in its form which fhowed it to be a natural cellular
ftrudture, fitted to be a refervoir for blood.

In fome of the veins leading from the placenta to the uterus, I per-
ceived that the red injection of the arteries, (which had been firft inje&ed)
had palled into them out of the fubftance of the placenta, mixing itfelf
with the yellow injection. I alfo obferved, that the fpongy chorion,
called the decidua, by Dr. Hunter, was very vafcular, its veffels coming
from and returning to the uterus, being filled with the different coloured
inje&ions.

After having confidered thefe appearances, it was not difficult for me
to determine the real ftrudture of the placenta and courle of the blood in
thefe parts; but the company, prejudiced in favour of former theories,
combated my opinion; and it was even difputed, whether or not thefe
curling arteries could carry red blood. After having dilTefted the uterus,
with the placenta and membranes, and made the whole into preparations,
tending to fhow the above fails, I returned home in the evening, and
communicated what I had difcovered to my brother, Dr. Hunter, who at
firft treated it and me with good humoured raillery; but 011 going with
me to Dr. Mc. Kenzie\'s, was foon convinced. Some of the parts were
given to him, which he afterwards fhowed at his le&ures, and prob-
ably they ftill remain in his colle&ion.

Soon after this time, Dr. Hunter and I procured feveral placentas, to
fee if after delivery the termination of the veins, and the curling arteries,
could be obferved : they were difcernible almoft in every one j and by

S pu (Ling

pufhing a pipe into the placenta, we could fill not only its whole iub-
ftance, but alio the veffels on that furface which was attached to the
uterus.

The facts being now afcertained, and univerfally acknowledged, I
confider myfelf as having a juft claim to the difcovery of the ftru&ure of
the placenta, and its communication with the uterus j together with the
ufe arifing from fuch ftrudtu-re and communication, and of having fir ft
demonftrated the vafcularity of the fpongy chorion.

It is not neceffary at prefent to enter into the various opinions which
have been formed on this fabjeft; becaufe, whatever they were, they
could not be juft, the ftrudxire of the parts not being known : neither
fhall I endeavour to give a complete defcription of all the parts imme-
diately connected with uterine geftation, but (hall content myfelf with de~
{bribing the ftrudture of the placenta, as far as it has any relation to the
uterus and child; and with explaining the connection between the two;
leaving the reader to examine what has been faid upon this fubject by
others, efpecially by Dr. Hunter, in that very accurate and elaborate
work which he has publiihed on the Gravid Uterus, in which he has
minutely defcribed, and accurately delineated the parts, without mention-
ing the mode of difcovery.

The neceffary connexion fabfifting in all animals between the mother
and foetus, for the nourifhment of the latter, as far as I know, takes
place in two ways. In fome it is continued, and fublifts through the
whole term of geftation ; in others the union is foon diffolved, but an
apparatus is provided, which at once furnifhes what is fufficient for the
fupport of the animal till it comes forth.

The firft of thefe are the viviparous, the fecond the oviparous, animals,
both of which admit of great variety in the modes by which they pro-
duce the fame effedt.^a In the firft divifion is included the human fpecies,

^a It may be remarked here* that the oviparous admit of being diftinguifhed into two clafTes,
one where the egg is hatched in the belly, as in the viper, which has been commonly called
viviparous ; the others, where the eggs have been firft laid and then hatched, which is the
clafs commonly called oviparous, fuch as all the bird tribe, and many others, as fnakes,
lizards, &c,

which

which alone will engage our prefent attention. But before I defcribe this
connection, it may be neceffary that the reader fhould understand my idea
of generation : I Shall therefore refer him to what I have faid upon that
fubjeCt in my account of the free martin/

In the human fpecies the anatomical Structure of the mother and em-
bryo, relative to fœtation, being well known, it will only be neceffaty
fully to defcribe the nature of that connection between them, which is
formed by the intermediate fubStance, called placenta. For this purpofe
we muft firlt confider the placenta as a common part ; next, the uterus,
as belonging to the mother, yet having an immediate connection with
the placenta, from which the nourishment of the fœtus is to be derived ;
which will lead us laftly to a consideration of thofe peculiarities by which
the foetus is to receive its nourifhment, and that conftitute its imme-
diate communication likewife with the placenta. It is the Structure of
this intermediate fubStance, and its connection with the child and the
uterus of the mother, which have hitherto been fo little understood ;
and without an accurate knowledge of which, it was impoffible any juSt
idea could be formed of its functions.

The placenta is a mafs lying nearly in contaCt with the uterus ; indeed
it may in fome degree be faid to be in continuity with a part of its internal
Surface. On the Side applied to the uterus the placenta is lobulated,
having deep irregular fiffures ; but all thefe lobes are united into one uni-
form furface next to the child, on which its umbilical veffels ramify.
When we cut into the placenta, its whole fubfiance appears to be little elfe
than a net-work, or Spongy mafs, through which the blood veffels of the
foetus ramify, and indeed it leems to be principally formed by the ramifi-
cations of thofe veffels ; exhibiting hardly any appearance of connecting
membrane : but we can hardly fuppofe it to be without fuch a mem-
brane, as there is fo much regularity in its texture. The cella, or inter-
stices of each lobe communicate with one another, even much more freely
than thofe of the cellular membrane in any other part of the body ; fo
that whatever fluid will pafs in at one part, readily diffufes itfelf through

^a Vide page 45.
S Z

the whole mafs of placenta, and all the cells have a communication at
the common bafe.

This ftrudture of the placenta, its reciprocal communication with the
two bodies with which it is immediately connected, and the ufe arifing
from this arrangement, form the union between the mother and fetus
for the fupport of the latter. Prior to the time I have mentioned above,
anatomifts feem to have been wholly unacquainted with this ft rue -
ture-of placenta. By notes taken from Dr. Hunter\'s lediures, in the
winter, 1755-6, it appears that he exprefled himfelf in the following
manner.³ " The fubftance of the placenta is a flefhy mafs, which
feems to be formed entirely of the veflels of the umbilical rope." In
another part, mentioning the appearances when injedted, he fays, " and
upon a flight putrefadtion coming on, you will find the whole appear-
ing like a mafs of veflels"; then fays, " there is always a white uninjedted
fubftance between the veflels, but whether lymphatics or what I cannot
tell." This uninjedted fubftance, mentioned by Dr. Hunter, is what
forms the cellular ftrudture.

The placenta feems to be principally compofed of the ramifications of
the veflels of the embryo, and may have been originally formed in con-
fequence of thofe next to the uterus laying hold by a fpecies of animal
attraction of the coagulable lymph which lines the uterus. This might
take place in a manner refembling what happens when the root of a
plant fpreads on the furface of moift bodies ; with this difference, that in
the prefent inftance the veflels form the fubftance through which they
ramify, as in the cafe of granulations.

At the time, or very probably before the female feed enters the uterus*
coagulable lymph, from the blood of the mother, is thrown out every
where on its inner furface, either from the ftimulus of impregnation taking
place in the ovarium, or in confequence of the feed being expelled from
it. When the feed has entered the uterus,, it attaches itfelf to that

^a Thefe quotations were taken from Mr. Galhie\'s MS. of Dr. Hunter\'s leflures, who is
one of the gentlemen that favoured Dr. Hunter, upon a former occafionj with the fame ufe of
his notes. Vide Dr. Hunter\'s Commentaries..

lymph

lymph, by which it becomes covered and immediately furrounded.^a
This coagulable lymph forms a foft pulpy membrane, the decidua,
which is, I believe, peculiar to the human fpecies, and to monkeys,
having never found it in any other animal. That part which covers the
feed or fœtus, where it is not immediately attached to the uterus, and
likewife forms a membrane, was difcovered by Dr. Hunter, and is
by him called decidua reflexa. The whole of this coagulable lymph
continues to be a living part for the time; the velfels of the uterus
ramify upon it ; and where the velfels of the fœtus form the placenta,
there the velfels of the uterus, after paifing through the decidua, open
into the cellular fubftance of the placenta, as before defcribed. As this
membrane lines the uterus and covers the feed, it is ftretched out, and
becomes thinner and thinner, as the uterus is diftended by the fœtus
growing larger, efpecially that part of it, called decidua reflexa, which
covers the fœtus, as there it cannot pofiibly acquire any new matter,
except we could fuppofe that the foetus afîîfted in the formation of it.
This membrane is moft diftinCt where it covers the chorion 3 for where
it covers the placenta it is blended with coagula in the great veins that
pafs obliquely through it, more efpecially all round the edge¹ where in-
numerable large veins come out ; but the chorion and decidua can be
eafily diftingui&ed from one another, the decidua being lefs elaftic.

From the defcription now given, I think we are juflified in fuppofing
the placenta to be formed entirely by the fœtus, and the decidua to be
a produdion of the mother ; and an additional proof of both thefe may
be drawn from the circumflance of the decidua paffing between the pla-
centa and uterus. For if the veffels of the fœtus branched into a part of
the decidua, we might conceive the whole placenta to be formed from
that exudation ; the portion of it where the veffels had ramified, like the
roots of a plant, becoming thicker than the reft, and forming the ⁿpla~
centa. If that were the cafe, this membrana decidua, when traced from
parts diftinCt, and at a diftance from the placenta, fhould be plainly feen

³ This is exactly fimilar to another operation in the animal ceconomy. If an extraneous
living part is introduced into any cavity, it will be immediately enclofed with coagulable
lymph. Thus we find worms inclofed, hydatids detached, and afterwards inclofed.

paffing

paffing into its fubftance all round at the edges, as a continuation of it.
But the fact is quite otherways -, for the decidua can be diftinftly traced
between the placenta and uterus, hardly ever paffing between the lobuli :
the veffels of the fœtus never entering into it, and of courfe none of
them ever coming in abfolute con tad: with the uterus.

The veffels of the fœtus adhering, by the intervention of the decidua,
to a certain fpace of the uterus when both are yet fmall, as the uterus
increafes in every part of its furface during the time of uterine geftation,
we muft fuppofe that this furface of adhefion increafes alfo ; and that by
the elongation of thofe veffels of the fœtus in every direction, this fub-
ftance fhould like wile be increafed in every direction : this is in fome
degree the cafe, yet the placenta does not occupy fo much of the enlarged
furface of the uterus as one at firft would expeét.

The veffels of the uterus in the time of the geftation, are increafed in
fize nearly in a proportion equal to the increafed circumference of the
uterus, and confequently-in a proportion much greater than the real in-
creafe of its fubftance. But when we refledt that the uterus ought not
to be confidered as hollow, but as a body nearly folid, on account of
its contents, which derive fupport from this fource and that a much
greater quantity of blood muft neceffarily pafs than what is required for
the fupport of the vifcus itfelf, we cannot be at a lofs to account for the
greatly increafed fize of its veffels.

The arteries of the uterus which are not immediately employed in con-
veying nourishment to it, go on towards the placenta, and proceeding;
obliquely between it and the uterus, pafs through the decidua without
ramifying ; juft before they enter the placenta, making two or three clofe
fpiral turns upon themfelves, they open at once, into its fpongy fubftance
without any diminution of fize, and without paffing beyond the furface
as above defcribed. The intention of thefe fpiral turns would appear to
be that of diminishing the force of the circulation as it approaches the
fpongy fubftance of the placenta, and is a ftruéture which muft leffen
the quick motion of the blood in a part where a quick motion of this
fluid was not wanted. The fize of thefe curling arteries at this termina-
tion is about that of a crow\'s quill.

The

The veins of the uterus appropriated to bring back the blood from
the placenta, commence from this fpongy fubftance by fuch wide begin-
nings as are more than equal to the fize of the veins themfelves. Thefe

O ^} 1

veins pafs obliquely through the decidua to the uterus, enter its fubftance
obliquely, and immediately * communicate with the proper veins of the
uterus. The area of thofe veins bear no proportion to their circumference,
the veins being very much flattened.

This ftrudture of parts points out at once the motion of the blood in
the placenta ; but as this is a fadt but lately afcertained, a juft idea may
perhaps be conveyed by faying, that it is flmilar, as far as we yet know,
to the blood\'s motion through the cavernous fubftance of the penis.

The blood, detached from the common circulation of the mother,
moves through the placenta of the foetus -, and is then returned back into
the courfe of the circulation of the mother to pafs on to the heart.

This ftrudture of the placenta, and its communication with the uterus,
leads us a ftep further in our knowledge of the connection between the
mother and fœtus -, the blood of the mother muft pafs freely into the fub-
ftance of the placenta, and the placenta moft probably will be conftantlv
filled ; the turgidity of which will aflift to fqueeze the blood into the
mouths of the veins of the uterus, that it may again pafs into the com-
mon circulation of the mother : and as the interftices of the placenta are
of much greater extent than the arteries which convey the blood, the
motion of the blood in that part muft be fo much diminifhed as almoft
to approach to ftagnation ; fo far and no further does the mother appear
to be concerned in this connection.

The foetus has a communication with the placenta of another kind.,
The arteries from the fœtus pafs out to a confiderable length, under the
name of the umbilical chord, and when they arrive at the placenta,
ramify upon its furface, fending into its fubftance branches which pafs
through it, and divide into final 1er and fmaller, till at laft they terminate
in veins ; thefe uniting become larger and larger, and end in one, which
at laft terminates in the proper circulation of the fœtus.

This courfe of veflels, and the blood\'s motion in them, is fimilar to the
courfe of the veflels and the motion of the blood in other parts of the body,

OBSERVATIONS

OBSERVATIONS ON THE PLACENTA OF THE MONKEY.

Monkeys always copulate backwards; this is performed fometimes
when the female is Standing on all-fours ; and at other times the male
brings her between his thighs when he is fitting, holding her with his
fore paws.

The female has her regular periods for the male, but fhe has commonly
too much complaifance ever to refufe him. They carry this Still further,
for they receive the male when with young, even when pretty far gone;
at leaft this was the cafe with the one I am going to give an account of.

A female monkey, belonging to Mr. Enderfbay, in the fummer 1782,
had frequently taken the male. The keeper obferved that after the 21ft
of June fhe became lefs lively than ufual, although it was not fufpedted
that fhe had conceived. However, fome time after, fhe appeared to be
bigger in the belly, which created a fufpicion of her being with young.
Great attention was paid to her, and great care was taken of her. She
went on gradually increafing in fize, and at laft fomething was obferved
to move in her belly at particular times, and the motion could even be
felt through the abdominal mufcles. She became indolent, and did not
like to leap or perform her ufual feats of activity. Towards the latter
part of the time they perceived the breaft and nipple to have become ra-
ther fuller; and that a kind of water could be fqueezed out at the nipple.
Some time before fhe brought forth, fhe \'became red about the hips and
pofleriors; which rednefs extended to the infide of the thighs, and It
was now certain fhe was with young. I defired that fhe might be parti-
cularly attended to when there were figns of approaching delivery, both
on her own account and that of the young one, and requefted the after-
birth might be carefully preferved, as that part would afliffc to afcertain
the mode of uterine geftation. Thefe directions were attentively followed;
and when in labour it was obferved, that fhe had regular pains; that
when the young one was in part come into the world, fhe affifted herfelf
with her fore paws; and that it came with the hind parts firft. This

happened

happened on the 15th of December 1782, in all about fix months after
conception j and when fhe brought forth her young one, it fhowed
figns of life, but died immediately, owing probably to the unfavourable
mode of its being brought into the world. When delivered, Ihe took the
young one up, and although it was dead, clafped it to her breaft.

The after-birth was preferved entire, and was perfectly fit for exami-
nation. It confifted of placenta, with the membranes and navel firing,
which all very much refembled the correfponding parts in the human
fubjed, as will now be defcribed.

The placenta had the appearance of being divided into two oblong
bodies, united by their edges, each terminating in an obtufe point at the
other end, which were of courfe at fome little diftance from one another.

It is probable, that thefe two points were placed towards the openings
of the Fallopian tubes, where the uterus a flumes a form refemblmg two
obtufe horns.

The two lobes above mentioned, were made up of fmaller ones,
united clofely at their edges, which were more apparent and diftind at
fome parts than at others. Some of thefe lobes were divided by fiffures
which feem to be derived from one centre; while there were others near
the edges, palling in a different direction : in which fiffures are placed
veins or finufes that receives the blood laterally from the lobes. The fub--
ilance of the placenta feems to be cellular, as in the human fubjed; this
ftrudure allows a communication to be kept up between different parts
of each lobe, and the finufes allowing of a communication between the
different lobes of which the placenta is compofed, and the blood paffes
into the fiffures before it enters the veins ; in which refped it differs from,
the human placenta.

The arteries from the uterus, on the furface of the placenta, were
dfible, but too fmall to be injeded y I cannot therefore fay how they
treminated in the placenta.

The principal veins in general arofe from the fiffures beginning from
the furface, as in the human placenta; but befides thefe, there were other
Imall ones, all which we may fuppofe pafs through, the decidua and;

T enter

enter the fubflance of the uterus, mod probably in the fame way as in
the human.

The membranes are the amnios, the chorion, and the membrana deci-
dua. Theie appear to be very much the fame as in the human, except
that the decidua is conliderably thicker, efpecially where it paffes between
the uterus and the placenta.

The navel firing in the monkey is not proportionally fo long as in the
human ; and is very much, and very regularly twilled.

There is no urachus, and of courfe no allantois, not even the fmall
ligament that appears to be a drawing in of the bladder at its attachment
to the navels the bladder here being rounded.

EXPLANATION

EXPLANATION OF THE PLATE«

APart of a uterus at the ninth month of utero-geftation, with a
portion of the placenta, to fhow the mode in which the blood-
velTels of the mother communicate with it.

A The fubftance of the uterus, feparated from the placenta, and turned
back.

B The furface of the placenta by which it is attached to the uterus,
covered by the decidua.

C The angle of reflection, at which the uterus is turned back upon it-
felf.

D The edge of the placenta.
E The decidua covering the chorion.

Upon the furface of the uterus are to be feen the veins or finufes,
running in an oblique direction, filled with wax, and broken
off where they pais through the decidua.
a a a a The arteries injected and broken off as they pafs from the uterus
to the placenta.

b b b b The continuation of thefe arteries, which make feveral fpiral
turns as they dip into the decidua, and afterwards terminate on the

furface of the placenta.
cc-cg The veins injected and broken off where they pafs into the fub-
ftance of the uterus,
d d d d The correfponding portions of the fame veins, where they pafs

from the placenta through the decidua.
eeee The blood-veffels, ramifying upon the decidua, broken off from
the uterus,

1 • •■.

OBSERVATIONS

OBSERVATIONS ON THE GILLAROO TROUT,
COMMONLY CALLED IN IRELAND THE
GIZZARD TROUT.

ONE of the digeftive organs of this trout being fo very remarkable
as to have given name to the fifh, and to be looked upon as its
diftinguifhing charadteriftic ; it will be necefTary to take a general view of
the varieties in the digeftive organs of animals, to be able to determine
what place the ftomach of this particular trout holds among them, and
to throw fame light upon the queftion, whether its refemblance to a
gizzard be fuch, as to render the name of gizzard trout a proper appel-
lation. For this purpofe let me ft ate fome general fa£ts. Food of ani-
mals may be divided into two kinds, what does, and what does not„
require maftication to facilitate digeftion. All animal food is of this
latter kind. But grain, and many other fubftances which ferve for ali-
ment, require a previous grinding or trituration ; and therefore animals
which live on fuch food are furnifhed with organs for that purpofe,
Granivorous quadrupeds have the two powers, for maftication and di-
geftion, feparate or diftinft from one another ; the fir ft being executed by
a fet of teeth of a particular form, which ferve as fo many grindftones for
reducing their food to a powder, before they convey it into the ftomach
for digeftion. When fo prepared, it is, with regard to the digeftive
power, rendered fimilar to animal food : therefore in many fuch animals,
the ftomach is fimilar to that of the: carnivorus y and whenever the
ftomach in granivorous quadrupeds departs from this general rule, there
is a Angularity in the operations of digeftion. Such birds as live upon
food, for the digeftion of which trituration is indifpenfably neceffary,
have the powers of maftication and digeftion united in one part, the giz-
zard which is peculiarly conftructed for that purpofe. In granivorous
birds therefore one lingle organ anfwers both to the teeth and ftomach
of granivorous quadrupeds, and confequently the gizzard alone of birds

T 2 will

will point out the food of the fpecies as clearly as the teeth and ftomaeh
together do in thofe animals in which the two offices of maftication and
and digeftion are not joined together in the fame part.

As it appears then to be the difference of the ftomachs only, that fits
birds for their different kinds of food, it is evident that every gradation of
ftomaeh muft be found among them, from the true gizzard which is one
extreme, to the mere membranous ftomaeh which is the other fince the
food of different fpecies is of every different kind, from the hardeft grain
to the fofteft animal matter. In confequence of this, it muft be as diffi-
cult to determine the exadt limits of the two different confirmations, to
which the names of gizzard and ftomaeh fpecifically belong, as, in any-
other cafe, to diftinguifh proximate fteps in the flow and imperceptible
gradations of nature.

The two extremes of true gizzard, and membranous ftomaeh, are eafily
defined; but they run fo into each other, that the end of one and the
beginning of the other are quite imperceptible. Similar gradations are
obferved in the food; the kinds fuited to the two extremes mixing toge-
ther in different proportions, adapted to the intermediate ftates of ftomaeh.

A true gizzard is compofed of two ftrong mufcles placed oppofite, and
a&ing upon each other, as two broad grindftones. Thefe mufcles are
joined together at their fides by a middle tendon, into which the mufcular
fibres are inferted, and which fdrms the narrow anterior and pofterior fides
of the flat quadrangular cavity, in which the grinding is performed. The
upper end of this cavity is filled up by the termination of the cefophagus,
and the beginning of the inteftine. The lower end confifts of a thin
mufcular bag connecting the edges of the two mufcles together.

By thefe two fofter and flexible fubftances being thus interpofed be-
tween the two ftrong grinding mufcles, a double advantage is gained ; for
whilft one gives an eafy paflage to the cefophagus! and gut, they both aCt,
in fome degree, as a hinge, on which the two mufcles may be faid to
move, by means of the middle tendon allowing of a free motion of the
grinding furfaces on each other, which is neceffary for the comminution
of food.

The

The two flat lateral fides of the grinding cavity are lined with a thick
horny fubftance flmilar to a hard and thick cuticle : the narrow anterior
and pofterior tendinous parts are alio lined with a cuticle, but not fo
ftrong as the former: this horny fubftance is gradually loft at one end
in a very thin cuticle, which lines the paflages of the oefophagus and
Inteftine for a little way; and at the other end is loft in the fame manner
in the membranous bag.

The two large mufcles may be considered as a pair of jaws, whole
teeth are taken in occafionally, being fmall rough ftones or pebbles which
the animal fwallows : and from the feeling on the tongue, it can diftin-
guifh fuch of thefe as are proper, from thofe which are fmooth or other-
ways unfit for the purpofe, which laft it inftantly drops out of its mouth.

Some birds, with gizzards, have a craw or crop alfo, which ferves as
a refervoir, and for foftening the grain; but as all of them have not this
organ, it is not to our prefent purpoie.

There are other animals befides that clafs of birds, which mafticate
their food in their ftomach, but their teeth are placed there by nature:
crabs and lobfters are of this kind.

The gradation from gizzard to ftomach is made by the mufcular fides
becoming weaker and weaker, and the food keeps pace with this change,
varying gradually from vegetable to animal. In one point of view there-»
fore food may be confidered as a firft principle, with refped to which the
digeftive powers, with their appendages, are as fecondary parts, being
adapted to and determined by the food, as the primary object.

We find then that in granivorous animals of all forts, there is an ap-
paratus for the maftication of the food, although of different kinds and
differently placed. But in true carnivorous animals of whatever tribe,
maftication is not fo neceflary, and therefore they have no apparatus for
that purpofe. The teeth of fuch quadrupeds, as are carnivorous, ferve
chiefly to procure food and prepare it for deglutition. The fame thing
holds in the true carnivorous bird, the office of whofe beak and talons i£
to procure the aliment, and fit it for deglutition, correfponding in this
refpect to the teeth of the others. Applying this to fifh, it feems, at firft
fight, that there is no occafion in them for that variety of ftru&ure in the

digeftive

digeftive organs, which is found in the before mentioned quadrupeds and
birds ; the food of fifh being principally of one fort, namely, animal,
which however with regard to the digeftive powers, is to be diftinguifhed
into two kinds, viz. common foft fifh and fhell-fifh. Such fifh as live
on the fir ft kind, have like the carnivorous quadrupeds and birds, no
apparatus for maftication ; their teeth being intended merely for catching
the food and fitting it to be fwallowed. But the fhells of the fecond
kind of food render fome degree of mafticating power neceffary, and ac-
cordingly we find in certain fifh a ftrufture fuited to this purpofe.

Thus the mouth of the wolf-fifh is almofl paved with teeth, by means
of which it can break any fhells to pieces, and fo effectually difengage
the food for digeftion, that though it lives upon fuch hard food, the
ftomach does not differ from that of other fifh : the organs of maftication
and digeftion therefore in this animal exa£tly correfpond to thofe of many
granivorous quadrupeds.

Other fifh, on the contrary, approach nearer to the ftruCture of birds,
in having their ftomach furnifhed with fome degree of mafticating power;
this in many is very imperfect, compared with the gizzards of fowls,
though perhaps the difference is fuch only as the difference of food will
properly allow: for in thofe fifh who have this power, the food being
Hill animal; and in general but imperfe&ly covered with the fhell, it per-
haps wants only to be broken ; however, in the bulla lignaria of Lin-
naeus, this apparatus is more perfedt, confifting of two bones, which we
muft fuppofe capable of grinding hard fhells; whereas the food of
granivorous birds requires to be ground into a kind of meal..

Of all the fifh I have feen, the mullet is the cleareft inftance of this
itrudture 3 its ftrong mufcular ftomach being evidently adapted, like the
gizzard of birds, to the two offices of maftication and digeftion. The
ftomach of the fifh now before us holds the fecond place.

But ftill neither of thofe ftomachs can be juftly ranked as gizzards,
fince they want fome of the moft effential characters-, viz. a power and
motion fitted for grinding, and the horny cuticle, The ftomach of the
Gillaroo trout is however more circumfcribed than that of moft fifh, better:
adapted for fmall food₅ and endued with, fufficient ftrength to break the

fhells

(hells of fmall fhell-fifh; which will moft probably be beft done by
having more than one in the ftomach at a time, and alio by taking pretty
large and fmooth ftones into the ftomach, which will anfwer the purpofe
of breaking; but not fo well that of grinding; nor will they hurt the
ftomach as they are fmooth, when fwallowed; but this ftomach can
fcarcely poffefs any power of grinding, as the whole cavity is lined with
a fine villous coat, the internal furface of which appears every where to
be digeftive, and by no means fitted for maftication.

The ftomach of the Englifh trout is exactly of the fame fpecies with
that of the Gillaroo, but its coat is not fo thick by two-thirds.¹ How
far this difference in thicknefs of ftomach is fufficient to make a diftinCt
fpecies, or barely a variety of the fame, is only to be determined by expe-
riment.¹³

The cefophagus in the trout is confiderably longer and fmaller than
in many other claffes of fifh.

The inteftines are fimilar to thofe of the falmon, herring, fprat, &c.

The pancreas is appendiculated.^c

The teeth fhow them to be fifh of prey.

So far as we are led to determine by analogy, we rnuft not confider
the ftomach of this fifh as a gizzard, but as a true ftomach.

^s The Englifh trout fwallows fhell-fiih, and alfo pretty large fmooth ftones, which ferve
as kind of fhell-breakers.

^b Viz. Take fome Gillaroo trout, male and female, and put them into water in which
there are no trout, to fee if they continue the fame.

^e I chufe to give this name to the pancreas from its appearance,

some observations on DIGESTION.

THE paper which I formerly prefented to the Royal Society, on
the flomach being digefted after death, and which was published in
1772, in the 62^nd volume of the Philofophical Tranfaótions, feems to have
attracted the attention of Spallanzani, and others. I fliall therefore make
fome remarks upon the experiments and opinions of thofe gentlemen;
compare them with thofe of Reaumur, and give fome general fails and
obfervations of my own upon digeftion, and ihall conclude by adding a
copy of the above mentioned paper, wifh the hope that others will take up
the fubjeCt in a more enlarged point of view, and profecute an inquiry which
is of fo much confequence in the inveftigation of the operations of the ani-
mal ceconomy. I cannot, at prefent, fpare fufficient time to give my opinions
at large on this fubjedt, with all the experiments and obfervations I have
made upon it; but as foon as I have leifure I fhall lay them before the public.

The difcovery of parts has been a principal objeft in the refearches of
the young or practical anatomift ; but the connection, arrangement, mode
of action, and ufes of the whole, or of particular organs, have more com-
monly been referved for the confederation of thole whofe views were
extended further; and whofe powers of reafoning had been enlarged by
habits of obfervation and inquiry. Curious and fpeculative men have
likewife made attempts in this way, often without being fufficiently ac-
quainted with the ftru&ure of the parts they were about to confider; and
confequently ignorant of their relations and connections with one another.
They have not been contented to fpeculate concerning thofe which were
moil obvious, which might have led to ufeful knowledge but directed
by what bell fuited their fancy, they have principally attempted the moll
obfeure and intricate. Generation, or the mode of continuing the fpecies,
and digeftion, or the means of preferving the individual, have been with
them the great objects of inquiry ; but it does not appear that they have
been very fuccefsful. Digeftion, as being one of the molt important ope-
rations of the animal ceconomy, and moft obvious in its effects, fupplies

U a number

a number of facts to aftift in afcertaining its powers; yet little has been
hitherto made out towards investigating the various circumftances under
which it is performed.

The mode of dividing the food, for the increafe of its furface in fome
animals, fuggefted one method of explaining the procefs of digeftion;
and the fecretion of a juice, having the power of converting vegetable
and animal matter into a fluid proper for the purpofes of nutrition,
fumifhed another. Both thefe opinions have had their advocates j and
while one party contended for a mechanical power, fuppofed to exift in
the gizzard, the other had recourfe to a chymical power; and thefe laft
considered fermentation as the great agent in digeftion : but as they were
rather fpeculative philofophers, than practical anatomifts, they have
frequently been milled with refped: to the very faóts and obfervations
whofe refult was to decide the truth of their opinions. What, for inftance,
does it explain in digeftion, that the force of the gizzard of a turkey is
found equal to four hundred and feventy-three pounds ? Does it afford a
better folution of our doubts, than we £hould derive from determining
the force of the mill that grinds the wheat into flour ? Or, on the other
hand, will the moft correct idea of fermentation enable us to account for
the various phenomena in the operation of digeftion ? But we can have no
very high idea of experiments made by gentlemen and priefts, who, for
want of anatomical knowledge, have not been able to purfue their rea-
foning even beyond the fimple experiment itfelf.

The great objeét fhould have been, an endeavour to difcover the uni-
verfal agent in digeftion : for the digeftive organ is evidently conftrudted
in a different manner in different animals; the mechanical power for the
divilion of the food not being univerfal; and thofe gentlemen who
eonfidered this power in the gizzard as the immediate caufe of digeftion,
forgot that the fame effeót was produced in other claffes of animals, with
a different ftruCture of ftomach, by means of the grinding teeth. Thus
while the gizzard favoured the theory of the mechanical reafoner, that
idea was again deftroyed by the membranous ftru&ure of the ftomach in
many animals, which at the fame time fupplied the chymift with argu-
ments in favour of the procefs of fermentation»

It

It is indeed a more dilf cult matter than thole gentlemen imagine, to
acquire on this fubjed a knowledge fufficiently accurate, to be able to
explain a procefs fo complicated as that of digeftion. There are in
Nature\'s operations always two obvious extremes and the mind of man
eagerly adopts that which accords with fome principle he is fond of, and
with which he is heft acquainted; but the intermediate connections and
gradations being lefs ftriking, do not fo forcibly affed the fuperficial
inquirer.

It happens unfortunately that thofe who from the nature of their edu-
cation are belt qualified to inveftigate the intricacies, and improve our
knowledge of the animal ceconomy, are compelled to get their living by
the practice of a profeffion which is constant employment. The only
idle profeffional men are thofe of the church; and we therefore frequently
fee them becoming philofophers and phyliologifts, as it were inftindively,
without having had that kind of education which might dired their pur-
fuits. Experiments, it is true, may be made by fuch men ; but they
rnuft not be complicated, nor having any immediate relation to a branch
of knowledge, with which they cannot be much acquainted; and ex-
periments fo made, will feldom go further than perhaps to explain a
fingle fad. They may look through microfcopes and examine the red
globules of blood; they may view animalcule and give us a candid rela-
tion of what they fee ; but fhould not prefume to carry their reafoning
into a fcience of which they can know nothing ; or hope to throw light
on a fubjed which it is impofllble they can underftand. It fhould be
remembered, that nothing in nature ftands alone; but that every art
and fcience has a relation to fome other art or fcience, and that it requires
a knowledge of thefe others, as far as this connedion takes place, to
enable us to become perfed in that which engages our particular atten-
tion.

Thefe obfervations are applicable to all thofe who have made experi-
ments to explain digeftion. The mechanical powers being eafily under-
ftood, thofe who confidered digeftion mechanically have in general ex-
plained their effeds juftly, as fat as they applied to the gizzard; but
their powers of reafoning went no further, and they fuppofed thefe effeds

U 2 to

to be digeftion. But thofe who took it up chymically being lefs ac-
quainted with chymiftry, and totally ignorant of the principles of the
animal (economy\', have erroneoufly referred the operations of the animal
machine to the laws of chymiftry.

The fir ft inquirers into digeftion were ftruck only by the extremes,
the gizzard, and membranous ftomach, paying no regard to the grada-
tions leading from the one to the other; which if properly examined would
have affifted them more effectually to explain the functions of the ftomach.

Vallifneri, confidering the power of the gizzard in one view only,
imagined it would be as liable to be affected by the mechanical powers
neceffary for digeftion, as the grain which was to be digefted; therefore
fuppofed the exiftence of a folvent: but he is entitled to no merit from
this idea, as the premifes are falfe : however, this opinion of Vallifneri
fet Reaumur to work, and has been the means of bringing feveral curious
facts to light. His experiments were firft made with a view to contra-
dict that idea ; and were therefore made upon birds that had gizzards,
as beft adapted to his purpofe. In this purfuit he only attended to thofe
parts of the experiments which beft accorded with his own opinion ; yet
carefully guarded againft every poftible accident that might affect their
accuracy. If trituration was the immediate caufe of digeftion, his
making experiments on the gizzards of birds was unneceffary ; it would
have been fufiicient to have examined the food after it had been mafti-
cated by the teeth of animals who have grinders j for the teeth and
gizzard anfwer one and the fame purpofe: but the circumftance of
animals who mafticate their food in their mouth, having alfo a ftomach,
ihould have taught, that there was fomething more in digeftion than,
trituration.

Reaumur\'s firft experiments were made to afcertain the ftrength of the
gizzard, with its effects ; to prove that fharp cutting fubftances, when
fwallowed, in no way injured its internal coat; and that the common food
of the bird was not diffolved when guarded againft its action. Yet after
all thefe proofs he feems to doubt, and fays, " are\'we to conclude that
grinding alone is fufficient to convert the grain and other aliment into a
matter proper for the nutrition of the animal, without undergoing any

other

other preparation ? Several reafons feem to oppofe this; trituration
alone might reduce the grain into a flour; but flour alone is not chyle."
" From the fmell of the aliment (taken from the gizzards of birds)
are we not led to conclude that it undergoes a fermentation ? This
fmell may be faid to arife from the liquor with which the aliment is
mixed; but is it likely that juices do not difpofe to fermentation,
fuch fubftances in which it is fo eaflly excited ? Flour made into a pafte
and fruit, require little more than heat to make them ferment." From
thefe very experiments made with a view to prove that digeftion is carried
011 by trituration, Reaumur was led to fuppofe a folvent. But as
there are fome birds whofe ftomachs do not feem fufficiently ftrong to
have the power of trituration, he /elected th© busaard, as being of that
kind, and the fitteft, for the fubje£t of his experiments, from the cir-
cumftance of its throwing up whatever is folid and indigeftible;\' therefore
without killing the bird, he could know the refult, and repeat the expe-
riment as often as he thought neceflary.

From the ftomach in the buzzard being incapable of trituration, he
concluded that a folvent was neceflary for digeftion ; but to preclude all
mechanical effects of the ftomach, in his experiments, he employed tin
tubes filled with meat, which, after the tubes had remained twenty-four
hours in the ftomach of the buzzard, was reduced to three-fourths of its
fize was like threads, and was neither putrid, four, nor volatile, but infipid.
On this effeCt he made his remarks, which are very pertinent. In another
experiment which was more accurate and conclufive, he is convinced of
the a£tion of a folvent.. He then tried the foft bones of young animals,
and found they were digefted; and that though the hard bones were not
aCted on fo readily 5 yet by returning the fame bones feveral times into
the ftomach, they were at laft digefted.

Reaumur was next anxious to know, if fuch birds as were intended
by nature to live upon meat, could alio digeft vegetables; but the refult
was not fo fatisfaCtory. He gave bread to his buzzard, which upon
being returned had the appearance of having been chewed. He next
tried a piece of a ripe pear ; which, after having been twenty-four hours
in the ftomach it had loft fome of its weight, and had the appearance of

beine;

being boiled or baked ; and thence he concludes that its powers are too
weak to digeft vegetables fo as to nourifh the animal.

To afcertain the nature of this liquor which had fuch powers, he tailed
the jelly to w^Thich the meat and bone had been reduced, conceiving it muft
be well impregnated with this fluid, but could only diftinguiih a bitter or
faltifh tafte. To have an opportunity of more fully determining the nature
of this folvent, he made his buzzard fwallow fmall tubes filled with
Iponge, which imbibed fifty grains of this liquor, having the fame tafte
as the jelly, and changing blue paper to a red. He tried the effedts of
this liquor on meat out of the body, with comparative experiments in
water; and after twenty-four hours, the meat in the water was become
putrid ; but that in the liquor from the ftomach was only foftened, not
diflfolved. To fee how far the analogy held good in membranous ftomachs,
he gave two bones to a dog, which being killed after twenty-fix hours,
they were found leffened in fize, and become as foft as horn. He found
that the ftomach of the dog did not alter the fhape of any of his cubes.

He conveyed grafs and hay, enclofed in tubes, into the ftomachs of
ruminating animals, which were not digefted, but appeared as if mace-
rated.

Let us enumerate the experiments and fadts made out by Reaumur.

The gizzard ivas not hurt by adting upon glafs, which it ground to a
powder.

The ftomach, or gizzard, had hardly any vifible motion.

The force of the gizzard was afcertained. ^ll3

The fize of the ftones found in the gizzard was in proportion to the
fize of the bird.

The ftomach of a buzzard digefted bone; from which he concluded
the gaftric juice has a folvent power ; but it did not digeft bread, although
it adted in a flight degree on fruit.

He made experiments with the gaftric juice.

The juice in the ruminating animals ftomachs produced no effedt on
hay or grafs, when inclofed in tubes.

Reaumur\'s experiments, although not compleat, yet paved the way
for future inveftigation 5 and Spallanzani proceeding on the fame ground,

has

has confirmed them by his own, and has filled up feveral blanks not
compleatly ma:le out by Reaumur; for in fome inftances Reaumur gave
up the point too foon, efpecially in the experiments refpedting the buz-
zard\'s power of digefting vegetables. Reaumur did not pofiefs general
knowledge fufficient to dired: him in his purfuits, which neceftarily con-
fined him to what he was moft mafter of, the mere making experiments.
He was neither an anatomift, nor a phyftologift nor can he be faid to
have been perfectly juft in his defcription of parts, having confidered the
crop, and the cefophagus leading from it to the gizzard, as being two
diftindt ftomachs. This however is only to be fet down as a piece of
anatomical ignorance, not affedting the fubjedt in the leaft. Spallanzani
is alfo incorrect in his anatomical knowledge but it muft be owned,
that his experiments, as far as they go, are in themfelves conclufive;
but like all mere makers of experiments, he is not fatisfied with thofe
which are clear and decifive, but multiplies them moft unneceftarily,
without varying them to elucidate other and efiential parts of the fame
fubjedt. I think we may fet it down as an axiom, that experiments
fhould not be often repeated, which merely tend to eftablifh a principle
already known and admitted; but that the next ftep fhould be, the ap-
plication of that principle to uleful purpofes. If Spallanzani had em-
ployed half his time in this way, and had confidered digeftion under all
the various ftates of the body and ftomach, with all the varieties of food,
both natural and artificial, he had employed his time much better than
in making experiments without end.

The food of moft animals being compofed either of vegetables, ani-
mals, or both, and a Iblvent admitted as an agent in digeftion , it only
remained to prove, that the effedt of the procefs of digeftion, was to
produce from thefe various fubftances, an animal matter, fimilar in all
animals who live on fuch fubftances. But the application of principles
requires more than fimply the knowledge of the principle itfelf; and
therefore thofe who cannot reafon from analogy, or draw general conclu-
fions from a few convincing fads j and who require to have every relative
conclufion or inference proved by an experiment, however unneceftary or
fatiguing to the reader, muft be pleafed with Spallanzani; but he mult

tire

tire even thofe whom he informed, and much more thofe who only read
his works in expectation of fomething new. Reaumur, feemed indeed
willing to give up the idea of trituration being the fole caufe of digef-
tion; but Spallanzani perfifts in proving that it is not performed by
trituration.

To make comparative experiments upon the digeffcive power of different
animals, they fhou" d be under the fame circumftances relative to digeftion:
they fhould be equal in age ; for the growing eat more than the full-grown,
and of courfe digeft fafter; and this point therefore can be beft afcertained
in each clafs of animals, by feledting thofe which have attained their full-
growth. They fhould be equal in fatnefs, for this makes a very material dif-
ference in the powers of digeftion in the fame animal and they fhould be
equal in health ; which laft circumftance, of all others, probably makes the
greateft difference in the powers of the ftomach. In comparing animals
of the fame clafs, the atmofphere fhould likewiie be of the fame tem-
perature ; for the different claffes of animals are varioufly affected by the
fame degree of heat. Experiments made upon fnakes and lizards in
the winter, will differ greatly from thofe made in the fummer, while
fimilar experiments made on dogs will have nearly the fame refult in both
feafons. Nor will the powers of the ftomach be found equal in the fame
clafs ; for fleeping animals, of the quadruped kind, as hedge-hogs, do
not digeft in the winter, but in the fummer only ; therefore the conclu-
fions to be drawn from experiments made refpe&ing the digeftive powers
in one, are not at all applicable to thofe made in the other feafon.

Spallanzani obferved that the fnake digefted food fafter in June, when
the heat was at 82° and 83°, than in April, when it was only 6o°_}
from whence he concludes, that heat afiifts digeftion; but this heat is
not the immediate, but the remote caufe of the increafed power: heat
having produced in the animal greater neceffity for nourifhment; and of
courfe greater powers j gaftric juice was therefore fecreted fafter or in.
greater quantity.

As a proof that heat does not a£t as an immediate, but only as a re-
mote caufe in affifting digeftion, I fhall mention the effeCt it produced

upon

upon a hedge-hog, the fubjedt of Mr. Jenner\'s third experiment on the
heat of that animal, related in the former part of this volume

" The hedge-hog, while the heat of the ftomach was at 30had
neither delire for food, nor power of digefting it; but when increafed
by inflammation in the abdomen to 93⁰, the animal feized a toad which
happened to be in the room; and upon being offered fame bread and
milk, it immediately eat it. The heat roufed up the actions of the ani-
mal ceconomy; and the parts being unable to carry on thefe actions
without being fupplied with nourilhment, the ftomach was ftimulated to
digeft, to afford them that fupply."

Spallanzani alfo mentions the flow digeftion in ferpents, and quotes
Bomare; who gives an account of a /crpcrit at Martinico, which after
having retained a chicken in its ftomach for three months, it was not
completely digefted, the feathers ftill adhering to the Ikin^b. The truth
of this fact I fhould very much doubt, efpecially in fo warm a climate
as that of Martinico; where I muft fuppofe the digeftive powers to be
conftantly wanted; unlefs in Martinico, as in colder climates, there is a
torpid feafon, in which the adt of digeftion is not neceffary : but in
that cafe the ferpent would not have fwallowed the chicken. When at
Bellifle, in the beginning of the winter 1761-2, I conveyed worms, and
pieces of meat, down the throats of lizards when they were going into
winter quarters, keeping them afterwards in a cool place. On opening
them at different periods, I always found the fubftances which I had in-
troduced, entire, and without any alteration : fometimes they were in the
ftomach; at other times they had paffed into the inteftine ; and fome of
the lizards that were allowed to live, voided them towards the fpring,
with but very little alteration in their ftrudture. So that digeftion is
regulated by the other actions of the body. Warmth requiring action
fuitable to that warmth ; the body requiring nourifhment fuitable to that
adtion; and the ftomach being called upon, obeys.

Spallanzani has made feveral attempts to prove what few will fubfcribe
to; that ftones in the gizzards of birds are of no ufe towards the break-

^b Bomare Did. d\'Hiftoire Nat,

X ing

ing or grinding down the grain ; and that they are picked up accidentally.
Thefe ftones have long been fuppofed to anfwer the purpofes of tritura-
tion : they have been considered as an affiftance to the ftomach, in the
manner of teeth, and of courfe neceifary for digeflion. Spallanzani com-
bats this opinion ; but as ftones are univerfally found in gizzards, he found
it neceifary to account for the mode of their being conveyed there, and at-
tributes it to chance. But we find that the gizzards which have moft
occafion for them, and are moft able to ufe them, are likewife beft fup-
plied with them : to corroborate which fadts, may be added what we
obferved before, that in the larger gizzards are to be found the largeft
pebbles. In a turkey, two hundred were found; in a goofe, a thoufand;
which could not depend entirely upon chance. In trying whether the ftones
were of fervice, Spallanzani put tubes, needles, and lancets, in gizzards in
which there were but very few ftones, and found them broken; but in this
experiment they had been forty-eight hours in the gizzards ; whereas in
the former experiments with the fame kind of tubes, thirty-fix hours was
the longeft time; in another eighteen hours; and in another the breaking
of thofe fubftances was begun in lefs than two hours ; therefore the ex-
periments were not perfectly fair, as the times were not equal. What he
thinks the moft conclufive, is where he had taken care there fhould be no
ftones, yet the hard indigeflible fubftances were adted upon much in the
fame way as when there were ftones ; but in this experiment he does not
give the time, which is very accurately ftated in moft of the others.

He found that the inner furface of the ftomach was not hurt by fuch
fubftances. Indeed it is fcarcely poffible for the inner coat of the ftomach
of a fowl to be pierced by fharp pointed fubftances ; its quantity of mo-
tion being fo inconfiderable, as hardly to make a body pafs through its
inner coat. But the principal reafon is, that this motion being lateral,
it does not prefs perpendicularly to its axis, but is one furface Hiding
in a contrary diredtion to another; and this not in a ftraight, but in a
circular diredtion, as will be explained hereafter.

In confidering the ftrength of the gizzard, and its probable effedts
when compared with the human ftomach, it mult appear that the giz-
zard is in itfelf very fit for trituration; we are not however to conclude

that

that ftones are entirely ufelefs; for if we compare the ftrength of the
mufcles of the jaws of animals who mafticate-their food, with thofe of birds
who do not, we (hall fay that the parts are well calculated for the purpofe
of maftication, yet we are not from thence to infer that the teeth in fuch jaws
are ufelefs, even although we have proof that the gums do the bufinefs when
the teeth are gone. If ftones are of ufe, which we may reafonably conclude
they are, birds have an advantage over animals having teeth, fo far as ftones
are always to be found, while the teeth are not renewed : he concludes,
" That we have at length a decifion of the famous queftion concerning
the ufe of thefe pebbles, fo long agitated by authors; it appearing that
they are not at all neceftary for the trituration of the firmeft food, &c." but
fays, ^<e He will, however, nut deny ttrat when put in motion by the gaftric
mufcles, they are capable of producing fome effects on the contents of
the ftomach." Now if we conftantly find in an organ fubftances which
can only be fubfervient to the functions of that organ, fhould we deny
them that ufe, although the part can do its office without them ?

To account for pebbles being found in the gizzards of birds, he fup-
pofes them picked up by chance, or by their not diftinguiftiing between
food and ftones. It appears lingular, that only thofe which have giz-
zards fhould be fo ftupid: he owns, that Redi and himfelf found that
birds died of hunger, without having picked up more ftones than ufual,
which we might fuppofe would not have been the cafe if they had no
choice; nor can ftones be confounded with the grain on which thefe birds
feed.

The ftones aflift in grinding down the grain, and by feparating its parts
allow the gaftric juice to come more readily in contact with it; they alfo
rub off the digefted furface, by which means the remainder is fooner brought
into con tad: with the gaftric juice.

It has been mentioned, that the motion of the gizzard is hardly ob~
fervable, and cannot be felt by the hand ; but for the purpofe of tritura-
tion that is not neceftary; for its cavity is very fmall, and adapted to
its contents, which it muft always be, or it cannot poffibly grind; and
therefore they require but little motion to affedt them. A fwelling and
collapfing, like the motion of the heart, would have no efteft. The ex-

X 2 tent

tent of motion in grinci-ftones need not be the tenth of an inch, if their
motion is alternate and in contrary directions. But although the mo-
tion of the gizzard is hardly vifible, yet we may be made very fenfible of
its adtion by putting the ear to the fides of a fowl while it is grinding its.
food, when we can hear the ftones moving upon one another.

It may be remarked, that the motion of the whole inteftinal canal,
from the. fauces, to the anus,, is naturally fo flow, as not to be excited into
quick motion. The food paftes flowly along the oefophagus; and even
in that of a man, fluids which might be expected to adt by their own
gravity, defcend but flowly. I imagine, however, we may be certain
that the cefophagus has always a regular contraction ; and that the lower
parts mull relax in progreflion, as it contracts above; fo that no poll-
tion of the body makes any difference in this action.

Upon expoiing the ftomach in living animals, we do not find it much
agitated or affected ; not even by handling or being irritated. The fame
thing may be obferved in the whole tract of inteftines ; and we find that
when the fasces are expelled by the action of the gut alone, that this ex-
pulfion is flow; the ftomach and redtum, however, can be emptied at
once j but this is done by the abdominal and other mufcles. We know
that the action of vomiting is performed entirely by the diaphragm and ab-
dominal mufcles ; and we know by the fame adtion the contents of the
rectum can be expelled.

. We need not feek for another power to empty the ftomach in vomiting,
thefe mufcles being" often capable of forcing the bowels themfelves out
of the abdomen, producing a rupture. It is not neceflary the ftomach
itfelf fhould adt violently to produce an evacuation of its contents ; nor
is it even neceflary it fhould adt at all. Since the lungs do not adt in
the leaft of themfelves, to throw up any extraneous matter; and a cough
to the lungs is fimilar to a vomit to the ftomach. The mufcles of ref-
piration are the active parts in emptying the lungs, and adt both natu-
rally and preternaturally. The mufcles of the thorax and abdomen do
not adt naturally on the contents of the abdomen, but often adt preter-
aiaturally, producing an evacuation from its vifcera,

There

There is reafon to believe that the natural motion in all ftomachs is re-
gular. What makes me of this opinion, is that appearance which takes
place in the ftomach of animals who are covered with hair, and who
lick their own bodies and of fuch as feed on whole animals, who are
likewife covered with hair. In the calf, for inftance, who licks his (kin
with his tongue, and fwallows whatever is attached to the rough furface
of that organ, balls of hair are often found in the cavity of the fto-
mach; on examining their furface, the hairs in each hemifphere feem to
arife from a centre, and to have the fame direction, which is circular,
and correfponding to what would appear to be the axis of this motion,
refembiing what we fee in different parts of the fkin of animals whole
hair take different turns. THIS regularity in the direction of the hair, in
fuch balls, could not be produced if there was not a regular motion in
the ftomach. This motion is alfo proved in the dog j for I have feen a
ball of this kind, that had been thrown up from a dog\'s ftomach, where
die fame regularity in the turns of the hair was very evident and com-
pleat. The fame motion feems alfo to take place in the bird kind : in
the cuckoo, for inftance, which in certain feafons lives on caterpillars,
fome of whom have hairs of a considerable length on their bodies, the
ends of thefe are found flicking in the inner horny coat of the ftomach or
gizzard, while the hairs themfelves are laid flat on its furface; not in
every direction, which would be the cafe if there was n© regular motion,
but all one way, ariiing from a central point placed in the middle of the
horny part; and this appearance on the furface of both fides of the giz-
zard correfponding. Thefe two fads prove, in my opinion, a regular and
circular motion taking place in the gizzard and membranous ftomach •
and therefore, molt probably, fomething Similar is carried on in all the
various kinds of Stomachs. Indeed this motion in the ftomach is fo con-
fiderable, than when there is no horny defence, we find the coats of the
ftomach fometimes pierced by hard pointed bodies. Thus the cows who
feed on the grafs of bleaching grounds have their ftomachs, efpecially
the fecond, ftuck full of pins; and fifh who prey upon, and fwallow
other fifh entire, often have their ftomachs pierced by the bones.

Spallanzant.

Spallanzani calls the inner coat, cartilaginous3 whereas, in fad, it is
a horny fubflance, forming an inner cuticle, but differing in fome refpe&s
from the common cuticle. This horny fubflance not only differs in flruc-
ture from the common cuticle, but in its attachment, from both cutLle,
nails, and hoofs. The cutis, where it is covered by fuch fubftances, has a
vafl number of villi on its furface, which oafs into correfponding perforations
in the cuticle, by which flrudture of parts, when the cuticle, nails, or hoofs
are feparated, their inner furface appears to be full of fmall perforations3
and the cutis from which they have been removed is villous 3 and thefe villi
are more numerous in fome parts than in others, where the fenfe of touch
is required to be delicate or acute. But the inner lining of the gizzard is
jufl the reverfe 3 that furface of the horny fubflance which is in contadfe
with the gizzard being villous 3 and when feparated, the inner furface of
the gizzard appears perforated. Thefe villi are the lafl formed parts of
?his horny fubflance, or are the fibres of which the horny coat is corn-
pofed. It is probable, that this horny fubflance takes the form of villi
that it may be more firmly connected with the inner furface of the
flomach 3 there being no occafion for acute fenfation in the flomach.

We may remark here, that the experiments made on the digeflion of
ruminating animals have been deficient, which arifes from this procefs in
them being more complicated than in the flomachs of other animals3
requiring attention to be paid to certain circumflances, which cannot
take place in flomachs of only one cavity.

The circumflance mentioned by Spallanzani, of the ruminating ani-
mals voiding the tubes, fhows that they are not careful the whole food
fliould be returned into the mouth to be chewed a fecond time 3 for if
they were, the tubes would certainly come up likewife, and would as
certainly be thrown out of their mouths as improper to be chewed,
which very often happened. But it was hardly neceffary to make expe-
riments to afcertain whether ruminating animals digefled -meat, when
we know that in fome cold countries, the cattle are fed on dried fifh3:
and mofl animals eat their own fecondines: indeed the circumflance of.
animals living upon both animal and vegetable food might have taught-
us, that the mode of digefling both (whatever it is) was the fame 3

therefore

therefore it could only be neceflary to difcover that mode; except we
abfurdly conceive, that two different modes might take place in the fame
ftomach at the fame time.

Spallanzani gives the opinion of authors refpedb\'ng digeftion; and fo
anxious is he to combat the idea of its being fermentation, that he
will hardly allow that fermentation ever takes place in the ftomach.
That fermentation can go on in the ftomach, there is no doubt; but
when this happens it arifes from the powers of digeftion being defec-
tive. It is often found that milk, vegetables of all kinds, wine, and
whatever has fugar in its composition, become much fooner four in
fome ftomachs, than they would, if left to undergo a fpontaneous
change out of the body: and even jfpirlts, In certain ftomachs, almoft:
immediately degenerate into a very ftrong acid. I am inclined to fuppofe,
that it is the fugar which is converted into fpirit, and the fpirit into
acid ; confequently a glafs of brandy, from being much ftronger, becaufe
lefs diluted, moft probably contains as much matter, likely to become acid,
as half a pint of wine. In other fubftances, befides thofe mentioned
above, the fermentative procefs (unlefs prevented by that of digeftion)
appears to begin fooner in the ftomach, than out of the body. All oily
fubftances, particularly butter, very foon become rancid after being
taken into the ftomach; and this rancidity is the effect of the firft pro-
cefs of the fermentation of oil. Mr. Sieffert has been able to reftore
rancid oils to their original fweetnefs, by adding to them their due quan-
tity of fixed air^a; the lofs of which I confider as the firft procefs in this
fermentation, fimilar to what happens in the fermentation of animal and
vegetable fubftances.

Animal food does not fo readily ferment in the ftomach, when com-
bined with vegetables, as when it is not; for the vegetables running more
quickly into fermentation, preferve the meat from putrefaction. Put a
piece of meat and fome fugar, or bread, into water, and let them ftand in
a warm place, the bread and fugar will begin to ferment, the water will
become four, and the meat be preferved : but the acid becoming weaker,

¹ Phyfical and chvmical E%s by Sir Tobern Bergman.

Mr

as the fermentation advances towards the putrefadtive, the meat at laft
begins to acquire the fame putrid difpofition. Of this Sir John Pringle
was not aware in making his experiments on this fubjedt. Yet this laft
part of the procefs cannot, I think, take place in the ftomach ; for a
fucceffion of acids will be formed, by which the meat will be preferred
fweet till it is digefted : the formation of this acid in the ftomach, moft
probably, not preventing the digeftion of thofe fubftances which are in-
capable of being rendered acid.

Bread allowed to remain in the ftomach of a dog for eight hours, is
fo much changed, that it will not run into the vinous fermentation; but
when taken out and kept in a warm place, becomes putrid: its putre-
faction, however, is not fo quick as a folution of meat that has been in
the ftomach for the fame length of time. Similar effedts are produced
when milk and bread are the food adminiftered; and probably the
gaftric juice, when in fuflicient quantity, will always prevent the vinous
fermentation.

Spallanzani\'s next trials were to determine, whether the gaftric juice
had the power of recovering meat already putrid; a fadt which might have
been proved by one experiment. For if very putrid meat is given to a
dog, and the dog killed after fome time, the meat will be found fweet,
and all putrefa&ion at an end. Therefore his allowing frefh meat to
continue a longer or Ihorter time in the ftomach was immaterial, as it
could not become putrid.

It appears from the above facts, that the ftomach has not fo much
power in preventing the acetous fermentation in vegetables, as in cor-
recting the putrefadtive difpofition in animal fubftances. For although
this cannot be certainly known in thofe who eat both animal and vege-
table food, yet it does not appear that the putrefaction of animal fub-
ftances (where nothing elfe is eaten) takes place fo quickly in the ftomach,
as the change which is produced in vegetables; the acetous difpofition
is therefore either ftronger than the putrefadtive, or it more readily takes
place.

It may be admitted as an axiom, that two proceffes cannot go on at
the fame time, in the fame part, of any fubftance j therefore, neither ve-
getable

getable nor animal fubftances can undergo their fpontaneous changes,,
while digeftion is going on in them; a procefs fuperior in power to
that of fermentation. But if the digeftive power is not perfect, then
the vinous and acetous fermentation will take place in the vegetable,,
and the putrefactive in the food of thofe animals which live wholly on
flefh. The gaftric juice therefore preferves vegetables from running into
fermentation, and animal fubftances from putrefaction; not from any
antifeptic quality in the juice, but, by making them go through another
procefs, prevents the fpontaneous change from taking place. In moft
ftomachs there is an acid, even although the animal has lived upon meat
for many weeks; this, however, is not always the cafe, therefore we
muft fupDole it is only formed occasionally. WLcthcx the ftomach has
a power of immediately fecreting this acid, or fir ft fecretes a fugar which
afterwards becomes acid, is not eafily afcertained: but I fhould be inclin-
ed to fuppofe, from analogy, the laft to be the cafe; for animals in health
feem to have the power of fecreting fugar, as we find in the milk, and
fometimes in the urine, from difeafe. The acid prevails fometimes to
fo great a degree, as to become a difeafe, attended with very difagreeable
fymptoms, the ftomach converting all fubftances which have a tendency to
become acid, into that form: the fugar of vegetables, and in fome ftomachs
even vinous fpirits, turning diredtly into acid. To afcertain whether
there is an acid naturally in the ftomach, it will be proper to examine
the contents before the birth, when the digeftive organs are perfedt, and
when no acid can have been produced by difeafe, or any thing that has
been fwallowed. In the flink calf, near the full time, there is no acid
found in the ftomach; although the contents have the fame coagulating
powers with thofe of-animals who have fucked*

As we find ftomachs poftefted of a power of diflolving the whole fub-
fiance of a bone, it is reafonable to fuppofe that its earth is deftroyed by
the acid in the ftomach. ¹

The ftomach appears not only to be capable of generating an acid, but
alfo to have the power of producing air ; but the laft effect, I believe, arifes
from difeafe in that vifcus. It may be difficult to account for the forma-
tion of this air; and as the ftomach is a refervoir for fubftances difpofed to

Y ferment

ferment, it might be fuppofed to arife from the food going into that pro-
cefs: but this, in my opinion, v/ill not account for the vaft quantity of
air frequently thrown up from fome ftomachs, even where food has not
been fvvallowed for a conliderable time, and where digeftion appeared to
have been compleated; which we muft conclude to have been the cafe,
from the food not having difagreed with either ftomach or bowels, and from
the ftools being good. When the gout falls on the ftomach, the quan-
tity of air thrown up is often immenfe. The fame thing may be obferved
in fome cafes which are commonly called nervous ; yet the procefs of
digeftion will not account for this formation of air, as no air is to be
found¹¹ in healthy ftomachs; neither is it to be accounted for from a
defedt in digeftion, as that would probably be productive of worfe con-
fequences.

1 am inclined to believe that the ftomach has a power of forming air or
letting it loofe from the blood, as a kind of fecretion : we can give no
abfolute proof of this taking place in the ftomach, as it may in all cafes
be referred to a defedt in digeftion: but we have inftances of air being found
in other cavities, where no fecondary caufe can be affigned. I have been
informed of air being detected in the uterus or vagina, without the perfons
themfelves knowing any thing of it, except by not having at the time of its
palling the fame power to prevent its efcape, as when it is in the redtum_}
from which circumftance they were always alarmed leaft it might make
a noife in its paftage. This fad; being fo extraordinary, rendered me
fomewhat incredulous ; but made me more inquifitive, with the hope of
being enabled to afcertain and account for it; and thofe of whom I have
been led to inquire, have always made the natural diftindtion, between air
palling from the vagina, and by the anus ; that from the anus they feel
and can.retain ; but that in the vagina they cannot; nor are they fenfible
of it till it paffes.. A woman, whom I attended with the late Sir John
Pringle, informed us of this fadt; but mentioned it only as a difagreeable
thing. I was anxious to determine, if there were any communication

² In all my experiments on digeftion, in dogs, I have never been able to detect any air
in the cavity of the ftomach.

between

between the vagina and redtum, and was allowed to examine, but dis-
covered nothing uncommon in the ftrudture of thefe parts. She\'died
fome time after; and being permitted to open the body, I found, no dif-
eafe either in the vagina or uterus. Since that time I have taken op-
portunities of inquiring of a number of women, concerning this cir-
cumflance, and by three or four have been informed exactly of the fame
fact, with all the circumftances abovementioned : how far they are to be
relied upon I will not pretend to determine. I have likewife found air in
the cellular membrane, in fome gun-fhot wounds that had palled fome
way under the (kin, without being able to account for its being there by
any mechanical erfedt of the ball.

That air, is either formed from the blood, or let loofe by fome adtion of
the velfels both naturally and from difeafe, is an undeniable fadt. We
find air formed in fome fifhes to anfwer natural purpofes; for in thofe
fifties whofe air-bladders do not communicate externally (many of which
there are) we muft fuppofe it to have been formed there. We alfo find
it in animals after death; and I have a piece of inteftine of a hog which
has a number of air-bladders upon it^a. I have often feen fuch veficles
on the edges of the lungs; but thefe may be fuppofed to have. been
kind of aneurifmal air-cells filled from the trachea, which may poffibly
be the cafe; but they are circumfcribed and impervious, fo that in the
ftate we find them, they have no communication with the external air. In
one inftance I have difcovered air in an abfcefs, which could not have
been received from the external air ; nor could it have arifen from putre-
fadtion the cafe is as follow:

A lady, about forty years of age, had been afflicted with complaints
in the bladder and parts connedted with it. From the fymptoms, her
difeafe was fuppofed by fome to be the ftone ; but upon examination no
ftone was found. She had alfo an umbilical hernia, for which I had been
confulted. She grew gradually worfe_; and from being a lufty became a
thin woman. A fmall tumor appeared in the groin, and the Ikin over it
became red, fimilar to an abfcefs when the matter is beginning to point

^a Vide Plate.

Y 2

externally; but before her death this fubfided. A few days before flie
died, I was defired to examine a fwelling on the lower and right-fide
of the belly, extending nearly from the navel to the fpine of the ilium
on the right-fide, and almofl of the fame width. It was a tenfe fwell-
ing, but evidently contained air, and could be made to found almofl
like a drum. It had come on within a very few weeks, and I felt my-
felf puzzled to account for it, there being clearly no connection between
that tumor and the umbilical hernia. I was inclined to fuppofe it to
be a ventral hernia, containing the csecum and part of the colon, filled
with air. But as £he had ftools ; as there were no fymptoms of a
flrangulated gut, nor any uneafinefs in the bowels, as I could not make
the air recede, but felt it as if confined to that part, I own I could not
conjecture what the cafe really was. The woman dying in a few days,
I was permitted to examine the body. That I might not interfere with the
tumor, or umbilical hernia, I made an opening into the abdomen on the
right-fide of the linea alba; and on examining the cavity of the ab-
domen, found every thing natural, except a fmall portion of the epiploon
adhering to the infide of the navel; but oppofite to the tumor, the
parietes of the abdomen were in a natural ftate. On preffing the
tumor by the hand, air was heard to make its efcape; but whether by
the vagina or anus was at firft doubtful. On examining with more at-
tention, it was difcovered to come from between the two labia. I now
opened the tumor externally, and let out the air, which was not in the
leafl putrid, and was contained in a fac tolerably fmooth on its infide,
made up of compreffed cellular membrane, the abdominal mufcles and
tendons forming the pofterior furface, which extended as low as the in-
ferior edge of Poupart\'s ligament. The contents of the abdomen were
tolerably found; but when I infpe&ed the vifcera. contained in the pelvis,
they were found adhering to each other; the bladder to the body of the
uterus ; the broad ligaments and ovaria, to the uterus ; and on exa-
mining thefe adhefions, I got into a cavity between the bladder, uterus,
and vagina, on the right-fide fomething like an abfcefs. From the right-
fide of this cavity there was a canal afcending to the brim of the pelvis,
in the courfe of the round ligament, as far as to the going out of the iliac

veffels,

veffels, which it feemed to accompany, and when it paffed from behind
Poupart\'s ligament, communicated with the tumor abovementioned. I next
endeavoured to difcover if there were any communication between the rec-
tum and the abfcefs, but could find none, the gut appearing to be quite
found. Having removed the whole contents of the pelvis, with the
canal leading to Poupart\'s ligament, and the ligament itfelf, with fuch of
the abdominal mufcles as compofed part of the fac, I found both the
re&um and vagina perfectly found. The uterus had a polypus forming
on its infide; neither the reCtum nor uterus had any connection with
the abfcefs; but there was a fmall communication between the abfcefs
and the bladder; that portion of the bladder which made part of the
abfcefs being very"much difeafed.

From this hiftory of the appearances of the tumor before death, and
the particular account I have given of the dhfedtion, the reader may be
able to make his own obfervations, and draw his own conclufions relative
to the origin of the air. It certainly appeared to have been formed in
this bag ; and it was only towards the latter end of her life that it could
have made its efcape into the cavity of the bladder; for it- was not poifible
to fqueeze the air out of the tumor, when I firft faw her; but juft before
death it became more flaccid. It could not be formed or let loofe in con-
fequence of putrefaction, for the air itfelf was free from any fmell; and
although the cavity between the vagina and bladder had on its internal
furface the irregular ulcerated appearance of an abfcefs, yet that on the
abdomen had not, was tolerably fmooth, and had rather the appearance
of having been formed in confequence of fome foreign matter accumula-
ting there.

This circumftance, of an animal having the power of forming air, or
feparating it from the juices by a kind of fecretion, appears at firft view
to be fupported by the experiments of Dr. Ingen-houfz \\

The Dr. obferved that, when we immerfe our bodies ^<( in a cold or
warm bath or, " By plunging the hand and arm even in cold water,"
that globules of air foon appear upon the fldn : and to be certain of the

^s Exp^ts upon Vegetables; proving their great Power of purifying the common Air, &c.

air

air coming from the body, he took all the neceffary precautions to pre-
vent the external air being carried into the water along with the body,
which would certainly be a confequence, if the body or part were im-
merfed quickly, or when dried. But although his experiments feem to
prove this opinion, yet I imagine there is a circumftance the Dr. did
not attend to at the time, which renders them very fallacious; for he
did not confider that water, commonly, contains a great deal of air ;
therefore the globules of air might as readily come from the water as
from the body this circumftance makes it neceffary to afcertain, by ex-*
periment, from whence the air comes which is attached to the body when
immerfed in water.

Water takes up air in proportion to its coldnefs, until it loles the pro-
perty of water and becomes folid : upon this principle we may account
for globules of air being found attached to the fkin when a part of the
body is immerfed in water colder than itfelf; for when we immerfe the
whole body we increafe the heat of the water, efpecially that next to the
lkin; and if we immerfe only a part, as an arm, it being commonly in
a fmaller quantity of water, the water immediately furrounding it is alfo
warmed. As a proof that, it is the air from the water, and not from
the furface of the body³, it matters not what the fubftance is that is im-
merfed, if it is but warmer than the water; for a piece of iron heated to
about 150°, immerfed in water about 70°, will warm the water in con-
tad with it fo as to make it part with its air. This effedt of heat is

^a « Count de Milly, in the Berlin Tranfaftions for the year 1777, publifhed experiments
to {how that there is an excretion of air; or, as it is termed, \' an aerial tranfpi ration,\' from
the whole furface of the human body during bathing in warm water: but Dr. Pearfon found,
on repeating thefe experiments, that there was no appearance of aerial bubbles on the furface
of the cuticle during bathing in warm water that had been previoufly boiled, fo as to expel
the air ufually mixed and united to river, and fpring-water. During bathing in the bath of
Buxton, the human body, after being immerfed, and kept at reft in it for fome time, is
covered with air-like bubbles ; but thefe bubbles appear, in the fame manner, on any folid
body whatever that may be placed in it. It is therefore fuppofed that the attraction to the
human body of the air, commonly fufpended in water, efpecially when heated to the tempera-
ture of a warm-water bath, has been miftaken for an excretion of air from the cuticle."

further

further proved, by making an experiment, with only this difference, that
the iron is to be ten degrees colder than the water; in this cafe little
or no air will be feparated, and of courfe no bubbles be obferved. The
bubbles of air do not appear to arife entirely from the degree of warmth
of the water, but alfo in fome meafure from a folid body being immerfed
in it, which appears to have a power of attracting the air, whofe affinity
to the water is now weakened by heat for limply heating the water to
the fame degree will not feparate the air, as we find, by experiment, that
no bubbles are produced : and this power of attracting the air appears, in
fome meafure, to depend upon the folidity of the body immerfed at leaft,
bodies have a greater number of bubbles in proportion to their folidity :

for Upon making comparative experiments between iron, Rone, wood,

and cork, the air feparated from the water upon the furface of the iron
and ftone is in confiderable quantity; that upon the wood very finally
and fcarcely any at all upon the cork.

It is perhaps impoffible to determine, with abfolute certainty, the feat
of digeftion 5 but it is more than probable it is principally in the ftomach:
this, however, will not be equally the cafe in all animals. We may
venture to affirm that, in the long contracted cefophagus of the quad-
ruped, digeftion does not take place ; and that the fecretion of this
part is a flimy mucus, poffeffed of no power fimilar to that of the
gaftric juice, being only intended to promote the eafy paffage of the
food i while the lower end of the cefophagus in birds is exceedingly
glandular, fecretes the principal part of the gaftric juice, and is a
fubftitute for the deficiency of the fecretion in the ftomach of this
clafs of animals, which in fome is lined with a horny fubftance, and in

others with a cuticle- But even in birds, the feat of digeftion IS chiefly

in the ftomach ; the juice fecreted in the lower part of the oefophagus be-
ing conveyed into that cavity. The mucus fecreted by the other parts of
the cefophagus, fuch as the crop in thofe who have one, has no fuch
power. It is pofiible, however, that digeftion may go on in the lower
part of the oefophagus; for if any aigeftible fubftance ftiould be retained
in it, as may happen in many of thofe who receive whole animals into
the ftomach, as the gull and heron, who fwallow fnakes and fifh entire,

the

the tails of which may remain in the cefophagus till the head is digefted;
in fuch a cafe the tail itfelf may likewife be a£ted upon. As a further
proof that digeftion is carried on principally in the ftomach, let us obferve
what happens to the yolk of an egg in the bird newly hatched. The
yolk is not in the leaft confumed in the time of incubation ; it appears
to be referved for the nourifhment of the chick, between the time of
hatching, and its either being fupplied with food by its parents, or being
able to procure it for itfelf -_y for we find, that although the yolk paftes
into the gut at fome diftance from the ftomach, yet it is carried up to
the ftomach to be digefted; and I have even feen it in the crop, being re-
tained there till wanted.

In thofe animals whofe ftomach confifts of feveral cavities, the precife
place where digeftion is carried on, has not been afcertained. I think, how-
ever, it may be fet down as a fa£t, that digeftion goes on in the fourth cavity,
This is beft proved by feeding the animal with a fubftance that does not
require any kind of preparation for digeftion, fuch as milk. Let a
calf be killed about half an hour after it has facked its mother, we fhall
find the whole milk, in the fourth cavity, firmly coagulated, and formed
into a ball; while the firft, fecond, and third cavities, contain only fuch
food as requires maftication, and what other preparation is neceffary to fit
it for digeftion; fuch animals have the power of conveying the food from
the cefophagus, either to the firft or fourth cavity, according to the na-
ture of the food; and for this purpofe there is a groove leading directly
from the cefophagus to the fourth ftomach, which I fuppofe can be con-
verted into a canal when wanted.

It is probable that digeftion is likewife carried on in the duodenum, es-
pecially in its upper part; which may arile from two caufes ; one, the
inteftine moft probably fecreting the fame juice with the ftomach the
other, fome of the gaftric juice, and alfo part of the food, having palled
into the inteftine before it had been converted into chyle.

Although the ftomach is the feat of digeftion, it is not folely appropri-
ated to that purpofe : in many animals it is not to be confidered as only
a digefting bag or bags, but in part as a refervoir for food. This is moft
remarkable in the ruminating animals, where the firft ftomach or bag is

merely

merely a refervoir, and in this refped is analogous to a crop. It is the
fame in the porpus, and, I believe, in moft animals of this clafs : although
it cannot be fuppofed that they return the food, as they have not the power
to mafticate. In fome animals, who do not ruminate, there is not the
fame neceffity for diftind pouches; the ftomach therefore confifis either
of one bag, lingly; or with appendages, as in the pecari. But the whole
of this bag is not endowed with the property of fecreting the gaftric juice,
there being a part whofe ftrudure is very different from that appropriated
to digeftion, which is covered by a cuticle, as in the firft, fecond, and
third ftomach of the ruminating animals, and in the firft ftomach of the
porpus. The pecari, the common hog, and the rat, are inftances of
this. This circumftance takes place, in a fmaller degree, in the horfe.
This increafe of the cavity of the ftomach, and its having appendages,
beyond what is neceffary for digeftion alone, is peculiar to thofe animals
who take in more food than what is immediately wanted, or which re-
quires a certain degree of preparation prior to digeftion. The crop in the
eagle is of the firft kind 5 and the crop in the gallinaceous fowls, and
the firft ftomach in the ruminating animals and porpus, is of the fecond.
It is the difpofition of fuch animals to fill thefe cavities, and the quan-
tity they contain, makes them feldomer require being filled; it is prob-
ably the fenfation produced from this fulnefs which gives fatisfadion to
the animal, and takes off the further defire for food, fimilar to what hap-
pens from filling the ftomach itfelf of other animals, who having no fuch
provifion, are longer and oftener employed in purfuit of food.

I fhould be apt to fuppofe the power of the gaftric juice to coagulate
milk and fome other animal mucilages², is a teft of the ftomach being the
feat of digeftion; for although milk may be coagulated by other fubftances,
\'yet when found in that ftate in the ftomach, it is probably for the purpofe
of digeftion ; as milk, and many other natural fubftances, require being co~

^a Milk is the fubftance commonly known to be coagulated by the gaftric juice : but I find
that it has alfo the fame power over the white of an egg. Give to a dog fome raw egg, and
kill him half an hour after he has fwallowed it, the egg will be found coagulated in his
ftomach, the fame as if boiled j the cryflalline humour, in the ftomachs of fifties, is likewife
found coagulated as if boiled,