THE V » *• t 
ANATOMY AND PHYSIOLOGY 
OF 
TIPI MWSlMf ®©®T> 
CONTAINING 
THE ANATOMY 
OF THE 
BONES, MUSCLES, AND JOINTS, AND THE HEART 
AND ARTERIES, 
BY JOHN BELL: 
* I 4 
AND 
THE ANATOMY AND PHYSIOLOGY 
OF THE 
BRAIN AND NERVES, THE ORGANS OF THE'SENSES, 
AND THE VISCERA. 
BY CHARLES BELL, F.R.S.E. 
SURGEON TO THE MIDDLESEX HOSPITAL, AND READER OF ANATOLIY IN THE 
CHAIR OF DR. HUNTER, &C. &C. 
FOURTH AMERICAN, FROM THE FOURTH ENGLISH EDITION. 
IN THREE VOLUMES, « ,t 
VOL. III.. 
NEW-YORK: ■V 
PUBLISHED BY COLLINS AND CO. NO. 189, PEARL-STREET. 
1822. WILLIAM BROWN, Pbintek, 
Philadelphia, THE 
OF THE 
HUMAN BODY. 
VOL. III. 
containing 
THE ANATOMY 
or 
THE ORGANS OF THE SENSES, 
THE VISCERA OF THE ABDOMEN, 
AND THE 
MALE AND FEMALE PARTS OF GENERATION CONTENTS 
OP 
THE THIRD VOLUME 
ANATOMY 
OP 
THE NERVOUS SYSTEM. 
1 1 
(continued.) 
OF THE SENSES. 
INTRODUCTION, 1. 
BOOK I. 
OF THE EYE. 
CHAP. I. 
Page 
Introductory View of the Principles of Optics 8 
Simple Idea of the Construction of the Eye 12 
CHAP, II. 
Of the Coats of the Eye 20 
' Of the Sclerotic Coat - - - - - ib. 
Of the Cornea - 22 
Of the Choroid Coat - - - - - 24 
Of the Ciliary Processes 27 
CHAP. III. 
Of the Iris 30 
Of the Muscular Fibres of the Iris - - 32 
CHAP. IV. 
Of the Retina, and Digression concerning the Seat 
of Vision - -- -- -- .35 
Digression on the Seat of Vision - - - 40 
Further Observations on the Retina - - 43 
Case I. of Nyctalopia, or Night Blindness - 48 
Case II. of Nyctalopia - - - - ~ ib. 
CHAP. V. 
Of the Membrana Pupillaris 52 CONTENTS. 
CHAP. VI. 
Page 
Of the Humours of the Eye 55 
Of the Aqueous Humour - ib. 
The Vitreous Humour ----- 58 
Of the Christalline Lens - ib. 
Of the Capsule of the Lens and Vitreous Humour 59 
CHAP. VII. 
Of the Distribution of the Central Artery and 
Vein of the Retina . - - - - - - 61 
CHAP. VIII. 
Of the Vascularity of the Pellucid Membranes 63 
CHAP. IX. 
Some Surgical Observations connected with the 
Anatomy of the Humours - - - - - 66 
CHAP. X. 
Of the Manner in which the Eye adapts itself to the 
D istance of Objects ----- 69 
CHAP. XI. 
Of Seeing in general ------ 77 
Parallel Motion of the Eyes - - - - 79 
Squinting - -- -- --82 
CHAP. XII. 
Of the Eyelids, of their Glands, and of the Course 
of the Tears - -- -- --88 
Of the Secretion and Course of the Tears - 90 
BOOK II. 
OF THE EAR. 
CHAP. I. 
Of Sound, and of the Ear in general - - - 93 
CHAP. II. 
General View of the Varieties in the Ears of Ani- 
mals - 95 
CHAP. III. 
Description of the Organ of Hearing in particu- 
lar Animals. 
In the Lobster and Crab - 101 
Of the Ear in Reptiles and Amphibious Animals 103 
Of the Ear in Birds ----- 105 
CHAP. IV. 
Of the Human Ear - - - - - - 107 
Section 1. Of the External Ear - ib. 
2. Of the Tympanum, or Middle cavity of 
the Ear, and its Diseases - - 110 contents. 
Pago 
The Anatomy of the Tympanum 110 
Of the Membruna Tympani - 112 
Of the Chain of Bones in the Tympanum 113 
Connection ancl Motion of these Bones 114 
Of the Muscles; within the Tympanum 117 
Of the Diseases of the Tympanum 120 
3. Oi the Labyrinth - 123 
Of the soft parts contained in the La- 
byrinth - - - 129 
4. Of the Nerve - - - - 130 
CHAP. V. 
Of Hearing in general - 132 
CHAP. VI. 
Of the D iseases of the Internal. Ear - - 137 
BOOK in. 
OF THE NOSE AND ORGAN OF SMELLING. 
Of the Sense of Smelling ... 140 
BOOK IY. 
OF THE MOUTH, SALIVARY GLANDS, AND ORGAN 
OF TASTE. 
CHAP. I. 
Of the Mouth and Tongue - - - 144 
CHAP. II. 
Of the Salivary Glands ... 146 
CHAP III. 
Velum Palatinum, Uvula, Arches of the Palate, 
and Amygdala - 148 
CHAP. IV. 
Of the Sense of Tasting - 151 
BOOK V. 
OF THE SKIN, AND SENSE OF TOUCH, 
Of the Skin - l53 
Of the Structure and Growth of the Nails - - 155 
Of the Hairs - 156 
Rete Mucosum - 157 
Of the True Skin - - - - 159 
Of the Organ of Touch - - - - 160 
Function of the Skin - - - - 161 
Explanation of the Plates - 164 contents. 
ANATOMY 
OF THE 
VISCERA OF THE ABDOMEN. 
INTRODUCTION. 
Page 
VIEW OF THE SYSTEM OF THE VISCERA AND OF THE 
STRUCTURE OF GLANDS, - - - .173 
CHAP I. 
Of the Abdomen in general, and of the Peritoneum 187 
CHAP II. 
Of the Viscera of the Abdomen - 196 
Of the (Esophagus - - - - 198 
Of the Seat, Form, Displacement of the Stomach - 201 
Of the Coats of the Stomach - - 203 
Of the Action of the Muscular Coat - - 204 
Of Rumination ----- 207 
Of Vomiting ----- 208 
Of the Nervous or Vascular Coat - - 210 
Of the Villous Coat - - - ib. 
Of the Gastric FJuid - - - - 211 
Of Digestion ----- 213 
Of Hunger and Thirst - 215 
Of the Intestines - - - - -216 
Of the Muscular Coat of the Intestines - - 222 
Of the Antiperistaltic Motion - 223 
Of the Vascular Coat - - - 226 
Of the Villous Coat - ib. 
Of the Glands ->---- 228 
Of the Great Intestines - 229 
Of the Function of the great Intestines - - 235 
CHAP. III. 
Of the Solid and Glandular Viscera of the Abdomen 236 
Of the Liver ----- 
Of the Function of the Liver and of the Secretion of the Bile 250 
Case of the Absence of the Vena Portas - - 253 
Of the Pancreas - 255 
Of the Spleen ----- 258 
Opinions regarding the Use of the Spleen - 260 
Kidney ------ 263 
Minute Structure of the Kidney - - - 265 
Ruysch’s Doctrine ----- 269 
Bertin’s Doctrine - - - 271 
Of the Office of the Kidneys - 272 
Of the Capsulae Renales - - - - 273 CONTENTS. 
ANATOMY 
OP THE 
VISCERA OF THE PELVIS. 
Page 
OF THE MALE PARTS OF GENERATION, 275 
CHAP. I. 
Of the Parts within the Pelvis - 276 
Section 1. Of the Bladder of Urine - ib. 
2. Of the Prostate Gland - 280 
CHAP. II. 
Of the Parts connected with the Viscera of the Pel- 
vis, but seated without it ----- 282 
Section 1. Of the Penis and Urethra - ib. 
2. Of the Testes - - - -, 288 
OF THE FEMAL*E PARTS OF GENERATION. 
CHAP. I. 
The External Parts of Generation - - 308 
CHAP. II. 
Of the Parts contained within the Female Pelvis - 317 
Section 1. Of the Bladder of Urine - ib. 
2. Of the Vagina; of its Shape, Connections, &c. 319 
3. Of the Womb - 322 
4. Of the Ovaria ----- 327 
Of the Mammae ----- 356 EXPLANATION OF THE PLATES. 
PLATE XXL 
This plate represents an ideal section of the abdomen, and 
the cut edge of the peritoneum is represented by the white line. 
а. The LIVER. 
B. The INTESTINES. 
C. The KIDNEY. 
D. The BLADDER of URINE. 
E. The RECTUM. 
1. The peritoneum, where it lines the abdominal muscles. 
2. The peritoneum, where it is reflected to form the ligament 
of the liver. 
3. The liver being represented cut through, we can trace the 
lamina of the ligament 2, over its surface 3, forming the 
peritoneal coat of this viscus. 
4. Marks the peritoneum reflected from the liver upon the 
diaphragm. 
5. Here the peritoneum is reflected off from the spine, to form 
one of the lamina of the mesentery. 
б. The peritoneal coat of the intestine, which we can trace 
round the circle of the gut until it unites again with the 
mesentery. , 
7 7. The peritoneum, forming the lower lamina of the mesen- 
tery. 
8. The peritoneum at that part where it is reflected, and co-* 
vers the kidney. 
9. The peritoneum is here descending upon the rectum E,we 
see it reflected over the gut, and descending again betwixt 
the rectum and bladder. 
10. The peritoneum, where it forms a coat to the fundus of 
the bladder. 
11. At this part we seethe peritoneum reflected up upon the os 
pubis, and from that we trace it to fig. 1. Thus we see, that 
the peritoneum can be traced round all its various inflec- 
tions and processes ; which shows, that it forms one con- 
tinuous sac, and that the intestines and the liver are equally 
on the outside of this membrane with the kidney. 
Explanation of Plate XXII. 
This plate represents the epidydimis and testicle, injected 
with quicksilver, and dissected. 
A. The body of the testicle with the tunica albuginea dissected off. 
B B. The seminal vessels in the body of the testicle or tubuli 
testis.* 
* Where the tubuli are emerging to form the rete vasculosum, or rete testis, 
they are called, the vasa recta. oL. Ill 
F.ii 
Plan. DraJX'ing of the Abdomen, Showing the Hi flections of the Pentoneurn 
Bell del* 
JLeney fc. /!,// ,jr// Vr/ m 
/v.?3. {fttmatf/ur/./z.. 
/ jr‘/J /jr / / 
/./•//• V/ I V / /£/ ill 
FI 2 4 
// e EXPLANATION OF THE PLATES. 
C. The rete testis formed by the union of the vessels B B. 
d. The vasa deferentia, which as they proceed from the 
testicle, are convoluted in a conical figure, and are called 
the VASCULAR CONES. 
e e. The epidydimis formed of the union of the vascular 
cones ; it is a little dissected and spread out. 
f. The vas deferens. 
Explanation of Plate XXIII. 
This Plate represents the prostate gland, vesiculse seminales, 
and lower part of the bladder, the parts being previously 
hardened in spirits, the vesiculse were afterwards cut open. 
a a. The body of the prostate gland ; it is that lower part 
of the gland which can be felt through the rectum. 
r. The prostate gland is here cut into and dissected, in fol- 
lowing the ducts of the vesiculse. 
c. The extremities of the ducts common to the vesiculse semi- 
nales and vasa deferentia. 
d d. The cells of the vesiculae seminales, which are laid open 
by a section. 
E. The left vas deferens, which is also laid open to show 
the cellular structure-which it assumes towards its termi- 
nation. 
F. The RIGHT VAS DEFERENS. 
g g. The foramina, by which the vasa deferentia open into the 
common duct. 
h. The lower and back part of the bladder. 
I. The RIGHT URETER. 
Explanation of Plate XXIV. 
This plate represents a section of the neck of the bladder. 
a. The lower part of the urinary bladder near the neck. 
b. The opening of the right ureter, which is marked 1. fig. iii- 
e c. The substance of the prostate gland, which is cut through; 
its thickness, texture, and the manner in which it sur- 
rounds the beginning of the urethra, will be understood 
from this plate. 
D. The urethra laid open. 
F. The VERUMONTANUM, or CAPUT GALINAGINIS. 
g g. The points of feathers put into the openings of the vesi- 
culae seminales and vasa deferentia. 
N. B. Round these ducts, on the surface of the verumon- 
tanum, and in that part of the urethra which is surrounded by 
the prostate gland, innumerable mucous ducts may be ob- 
served : into some of these small bristles are introduced. EXPLANATION OF THE PLATES. 
Explanation of Plate XXV. 
A view of the penis, vesiculae seminales, and prostate gland. 
Explanation of Plate XX VI. 
Fig. 1. 
An ovum in a very early stage, representing the shaggy 
surface of the true chorion. 
Fig.1 2. 
We may see here the foetus in a very early stage contained 
in the transparent amnion, and, attached to the outside of the 
amnion, the vesicula umbilicalis. 
N. B. These are not representations of the same abortion. 
Fig. 3. 
Represents the ovum a little more advanced. 
A. The Chorion. 
b. The Amnion. 
c. The Foetus hung by the Umbilical Cord. 
Explanation of Plate XXVII. 
This plate represents two views of a conception, we shall 
say about the first month, and here the decidua and the ovum 
have been thrown off together. This abortion was prepared 
so as to resemble the beautiful engravings in Dr. Hunters 
34th table. 
Fig. 1. 
The deciduous efflorescence formed by the womb, is seen 
here entire, and seen as if moulded to the cavity of the womb : 
it is only necessary to observe that it hung inverted. 
A. The lower part of the conception, which was near the neck 
of the womb, and which has some coagula of blood at- 
tached to it. 
bbb. Quills introduced within the decidua by an opening 
near the neck of the womb, and their points brought otD 
at that part of the membrane which answers to the open- 
ing of the Fallopian tubes : there it is either entirely de- 
ficient, or it is so thin that it has been torn at c c. 
Fig. 2. 
Here the other side of the conception is shown, and the 
ovum is seen to have adhered to the outer surface of the de- 
cidua. 
a a a. The quills introduced into the cavity of the decidua. 
b. The shaggy surface of the decidua, 
c c. The fleecy outer surface of the chorion. 
It is here to be observed that the ovum, c d e, may be 
supposed to be as it has descended from the ovarium, onlv VP. Ill 
PI 2S 
i. Crus firms E. Vesicalee Semen 
3. Bui6 of the Urethra EF. Vos a de/crcntea 
" Membranous fit ofthe Urethra G The Ureter 
0. Prostate ttlanch 71 Btadder coveredbvteeFerdoncum 
JJr/f , 
Z,nu;9 set Voi.m. 
Pl.iS 
Big".!. 
Fir.3. 
... *> ” Vo I .rix. 
M 27 
il. 
BV.e. Vd. Ill 
P. 28- 
6l*!£tll de!‘ 
//\y fW/t'ns j8lt>. Vo/ill 
F/ig 
P Mavcrirt sc* 
/\<b/tshnf by C iftio. EXPLANATION OF THE PLATES. 
somewhat enlarged, and it is here evidently on the outside of 
the decidua, but it has been torn open, and that deciduous 
surface which connected it to the surface of the womb at this 
place has been left with the womb, to be afterwards thrown off 
Avith the discharges. 
d. The delicate membrane of the amnios. 
E. The umbilical cord and part of the foetus. 
Explanation of Plate XXVIII. 
This and the following plate represents a conception of the 
third month, and as the abortion was thrown off very entire, 
we have another opportunity of observing the state of the de- 
cidua in a more advanced state. 
a. A thread passed through the more solid placentary mass 
suspending the whole. 
b b. The decidua, having a peculiar reticulated appearance, 
c c. Shreds of the decidua, where it has burst in the de- 
livery. 
i). The decidua reflexa, through which also the proper 
membranes have burst. 
E. The TRUE CHORION. 
f. Very small curling arteries which are entering the decidua, 
or what may be considered as the maternal portion of 
the placenta. 
Explanation of Plate XXIX. 
We have here presented a view of a section of the same 
conception. 
A. The DECIDUA. 
b b. The cut edge of the decidua, which will be seen to sur- 
round the whole ovum, and particularly it may be ob- 
served to form on the upper part a distinct lamina from 
the placenta F. 
c c. The DECIDUA. 
O. The DECIDUA REFLEXA. 
f. The placenta already formed by the accumulated vessels 
of the chorion. 
g. The chorion towards the lower part of the womb; here, 
it may be observed, the fleecy vessels have disappeared. 
H. The AMNION. 
f. The umbilical cord twisted three times around the neck of 
the foetus. THE 
MAWW 
of 
THE NERVOUS SYSTEM. 
CONTINUED. 
OF THE SENSES. 
INTRODUCTION. 
THE Senses are those faculties by which the active princi- 
ple within us has communication with the material objects by 
which we are surrounded. Through them we receive those 
simple sensations which are the first elements of our thoughts, 
and the means of developing all the powers of the understand- 
ing. The exercise of our senses, however, is familiar to us 
from so early a period, that we never think of attending to 
their first simple intimations: before we are capable of reflect- 
ing on the nature of the perceptions which the several senses 
convey, they are so complicated and distorted by habits and 
association, that observation comes too late for us to ascertain 
the simple progress of nature. Philosophy revives the natural 
feelings of wonder at the spectacle of the universe; but too 
often we follow the dictates of a creative imagination, and run 
into error and delusion in studying the operations of nature. 
To one who looks upon nature with the calm and chastened 
delight which is the character of true philosophy, there is a con- 
viction that such researches may be carried too far. Wherever 
he directs his attention, whether to the structure of the human 
body, the physiology of vegetables, or the phasnomena of 
chemical science; whether he endeavours to comprehend the 
system of the universe, or pores over the minutiae of natural 
history, he finds every where a limit placed to his inquiries; a 
line which no industry or ingenuity can enable him to pass. We 2 
OF THE SENSES. 
may please ourselves with conjecture beyond this limit, but 
we find that all our opinions on these subjects are merely a 
dream of something allied to the impressions of our gross 
senses. The agency of the senses, the intercourse betwixt 
mind and matter, and the influence of the will over the body, 
are mysterious, and, probably, inexplicable phenomena; yet 
wTe scruple not to explain them precisely and mechanically; 
we reduce them to the level of our own capacity in the same 
manner as we fabricate to ourselves the idea of a Deity by the 
combination of all human perfections. Yet when we imagine 
that we have discovered the secret of these mysteries, it is mor- 
tifying to find ourselves without any sign or language by which 
to communicate those great truths to the companions of our 
studies : we struggle for expression; and, as all our ideas upon 
such abstract subjects are derived from analogy, we express 
our opinions respecting the powers of the mind, or the man- 
ner in which we perceive the objects of the senses, in the same 
language, and by reference to the same notions, w hich belong 
to the sensations themselves. From this scantiness and inac- 
curacy of language, it unavoidably happens, that very different 
ideas of the operation of the senses are expressed by several 
men in the same terms ; and in attempting to convey our ideas 
in language more precise and definite, we are insensibly led 
to materialize the faculties of the mind, and to make the ope- 
rations of the senses merely mechanical. What other expla- 
nation can wre give of theories, which suppose the nerves to 
be tubes carrying animal spirits, or containing an elastic ether; 
or which represent them as vibrating chords, and reduce all 
the variety of sensation to the difference of tension and tone? 
These are, indeed, what Dr. Reid calls them, “ unhandy en- 
gines for carrying images.” 
Nothing has been undertaken in philosophy but entire sys- 
tems, fathoming at once the greatest depths of nature. The 
custom has been, to frame hardy conjectures; and if upon com- 
paring them with things there appeared some agreement, how- 
ever remote, to hold that as fully sufficient. What chimeras and 
monstrous opinions this method of philosophising has brought 
forth, it would be more invidious than difficult to specify. 
The principles of philosophising have been laid down on 
this basis, that on no account are conjectures to be indulged 
concerning the powers and laws of nature, but we are to make 
it our endeavour, with all diligence, to search out by experi- 
ment the real and true laws by which the constitution of things 
is regulated. In the subject now before us we have a very re- 
markable proof of the superiority of investigation by experi- 
ment over the lazy indulgence of conjecture; and I hope the OF THE SENSES. 
3 
whole tenor of the following account of the senses will strength- 
en the conviction of the student, that it is only by assiduous 
study, and patient observation of nature, that he is to look for 
the attainment of knowledge in the medical profession. 
The office of the brain and nerves is to receive the impres- 
sions of external bodies, by which corresponding changes and 
representations are made in the mind. We know nothing fur- 
ther than that, by the operation of the senses, new thoughts 
are excited in the'mind. Betwixt the sensation excited in the 
organ pf the external sense, and the idea excited in the brain, . 
there is an indissoluble, though inexplicable, connection; the 
brain is not sensible, nor does the eye perceive, but both to- 
gether give us the knowledge of outward things. But when 
the sensation is once received and communicated to the brain it 
is treasured there, and may afterwards be excited independent 
of the external organ: hence comes the term internal senses. 
Though I treat professedly of the external organs of the 
senses only, it may be necessary here to say a few words on the 
internal senses. It appears that all sensations originate in the 
external senses or organs receiving the impressions of outward 
bodies. When this change influences the mind, we call it per- 
ception. Memory is the power of recalling these sensations, 
and imagination is the power of combining them. These are 
powers of the mind, which, by the constitution of our nature, 
are gradually acquired, and increased by exercise. In infan- 
cy, the perceptions are simple and transitory; the memory is 
perfected by degrees, and with the store of ideas the imagina- 
tion is invigorated, but still it is kept limited to the idea re- 
ceived, not from, but in consequence of, the operation of the 
senses. 
It is in the combination and reciprocal effects of the men- 
tal powers and of the impression on the external senses, that 
we are to find an explanation of the operation of attention. 
When the mental powers are led to the contemplation of an 
idea which assimilates easily with the sensation about to be 
presented by the external organ, the perception is quick and 
vivid; but when the mind is strongly impressed and occupied 
with the contemplation of past ideas, the present operation of 
the sense is neglected and overlooked. Thus, the vividness of 
the perception or idea, is always proportionate to the degree 
of undistracted attention which the mind is able co bestow on 
the object of sensation or of memory. In solitude and dark- 
ness, the strength of the memory in the contemplation of past 
events is increased, because there is no intrusion in the objects 
pf the outward senses; and the deaf or blind receive some 
compensation for their loss in the increased powers which are. 4 
Ot"THE SENSES. 
acquired by a more frequent and undisturbed use of the senses 
which remain, and a keener attention to the sensations which 
they present. On the other hand, when we are under the 
enchantments of a waking dream or reverie, our attention is 
wholly detached from the present objects of the senses ; and 
in this state we may continue to read without understanding. 
This absence, in a certain degree, is common, natural, and 
by no means unpleasant: it is the exertion of the faculty of 
the mind. But it may become disease ; for health of mind 
consists in the due correspondence betwixt the excitement on 
the outward sense and the operation of the mind thus roused 
by the external sense. 
The mind (united to the body) suffers in the diseases of the 
body. In the debility of the body, in fever, in spasms, and 
pain, the faculties of the mind languish, or are roused to une- 
qual strength or morbid acuteness. Sometimes the phantasms 
and internal sensations of things once received by the outward 
senses, become so strong in the mind, as to be mistaken for 
objects actually present. Such phrenzy or delirium arises from 
a disordered and acutely sensible state of the internal senses'. 
These impressions being great in degree, hurry and bustle is 
in the countenance of the patient, and uncommon strength and 
violence in his actions, just as passion gives uncommon excite- 
ment to one in hfealth, causing a disregard or forgetfulness of 
all besides. In health, however vigorous the force of imagi- 
nation may be, there is still a conviction that the ideas which 
it presents are not realities, and the operation of the external 
senses preponderates in recalling the attention to what exists 
around us. But when the internal perceptions become so 
strong as to be mistaken for realities, the effect is falsel) attri- 
buted to real existences. It indeed sometimes happens, that 
this false perception is really owing to disease in the organ, a 
too vivid perception of things absent proceeding from an affec- 
tion of the brain, and not from an impression on the outward 
senses. 
There is still another degree or class of diseased sensation, 
consisting in the modification of the impression of objects 
which are actually present to the senses. This modification 
of things present (as when bodies actually at rest appear to be 
in motion) is not always occasioned by optical deception. 
Objects seem to turn round, and this we shall afterwards find 
to proceed from the insensible motion of the eyes ; but this 
motion of the eyes is occasioned by the disordered state of the 
internal sensation; and the same feeling will be experienced if 
the eyes be shut. For example, when vre turn quickly round 
on our heel until we become giddy, it would appear that there OF THE SENSES. 
5 
is a disturbance of the usual order of sensation, and that the 
course of our impressions is reversed; for while our sensations 
were formerly directed entirely by the impression made on the 
outward senses, the sensorial impressions now draw after them 
a sympathetic motion of the external organs. 
This inverted communication betwixt the mind and organs 
is better exemplified in the organ of speech. Thoughts ex- 
cited in the mind are represented by the signs of these ideas 
in speech. There occurs, however, not unfrequently, a dis- 
eased state of these operations of the internal senses, in which 
the ideas excited in the mind cannot be associated with their 
appropriate expressions; and although the patient has a dis- 
tinct idea of what he means to express, he cannot recollect the 
words which belong to it; so that, when he asks for one thing, 
he names another which has no connection with it. Of this 
he is perfectly sensible, and yet he cannot correct himself. 
There are more frequent instances of diseased corporeal 
sensation in hypochondriacs. In them, the sensation of pain 
and unusual feelings are falsely attributed to parts in which 
there is really no affection; for these feelings there is no ap- 
parent cause: they proceed from a disordered state of sen- 
sation in which the usual course of the impressions is altered, 
so as to occasion the patient falsely to attribute his suffering to 
sound and healthy parts. Thus indigestion, the irritation of 
the bile, flatulency, colic, &c. often do not give the usual im- 
pressions, but the pains are attributed to outward parts. That 
there is sometimes an actual connection existing betwixt the 
external parts, to which these feelings are referred, and the in- 
ternal organs, is evident from the fact, that pressure in the out- 
ward and sound parts has occasioned spasms in the internal 
organs. To such disordered transmission of the irritation of 
the internal parts we have to attribute the extravagant and 
ludicrous ideas which hypochondriacs entertain. In these 
people, there are diseases of parts, of the action of which, 
during their healthy state, (as I have already explained in the 
short introductory view of the nervous system,) we have no 
feeling nor consciousness, and over which the will has no 
power. But, although in the healthy state of the economy 
there is no immediate route by which any sensation from these 
organs can be transmitted to excite a mental perception, it may 
happen, tjbat, in their diseased state, when sensations do arise 
which forcibly attract the attention, an obscurity in the feelings 
produced by their derangement occurs, insomuch, that the 
mind may be deceived in regard to the direction of the sensa- 
tion conveyed from them. 
During health, there are vicissitudes of consciousness, sense, 6 
OF THE SENSES. 
and voluntary motion, and of rest from voluntary exertion, in- 
sensibility, and oblivion of the past. This is true, however, 
only comparatively, and by a gross reference to degree; for 
even during natural sleep there is not a total oblivion of past 
perceptions, nor is there always a total unconsciousness of the 
present, as the senses are in part awake; some one train ol 
ideas is present to the mind; and the lapse of time is observed. 
Even these perceptions are sometimes so strong as to be fol- 
lowed by voluntary exertion,and yet the patient remains asleep. 
Whatever conduces to take the excitement from the mind, or 
lessens the vivacity of its impressions, conduces to sleep. Thus, 
rest, stillness, and darkness, by excluding the most lively im- 
pressions conveyed by the senses; and hoemorrhagy and eva- 
cuations, by lessening the velocity of the circulation ; and cold, 
by lessening the sensibility ; induce sleep. Again, compres- 
sion of the returning blood from the head, by giving it a slow 
languid motion, and by depriving the vessels of their freedom 
of action, also conduces to sleep; because, as formerly re- 
marked, the powers and faculties of the brain must be reno- 
vated through the means of the circulation. 
By long watching and fatigue, the body is brought nearly to 
a feverish lowness. By sleep, rest is given to the voluntary 
muscles, and an abatement of the vital motions ensues ; the 
quiescent state of the muscles brings back the blood to the 
heart, with a slow, regular, and calm progression; the heart 
is restored to its slow and equable pulsation; the breathing 
becomes slower; and the wasted strength of the system is 
recruited. 
We may define sleep to be a state in which the sensations 
are dull, the voluntary muscles inert, and the vital motions 
calm and regular. In dreaming, the sensations are dull and 
obscure, but the imagination more alive and active ; unnatural 
sleep, or soporific diseases, may be characterised by the dis- 
ordered imagination, and disturbed vifhl and voluntary mo- 
tions. The vital actions, which are calm, slow, and equable, 
during natural sleep, become oppressed; the sensibilitj', which 
is gradually diminished upon the approach of sleep, but al- 
ways capable of being roused by the senses, becomes quite 
oppressed ; the voluntary muscles continue relaxed, as in sleep, 
or convulsed by irregular motions. In the oppression of the 
night-mare, we have the consciousness of sensation, but the 
power of motion is lost. In apoplectic diseases, the functions 
of the viscera proceed, and are but partially impeded; but 
when the circulation of the blood and play of the lungs are 
obstructed, the operations of the mind are not equally uncon- 
cerned in the paroxysm; thus in syncope, the sudden deple- of the senses. 
7 
lion of the blood-vessels of the brain causes instant loss of sense 
and of voluntary motion. 
If natural sleep is not profound, the imagination is aAvake; 
but there may be false perceptions, false judgment and asso- 
ciations, and disproportioned emotions ; and if sensations are 
perceived, they do not produce the ordinary associations. If 
such a state of the intellectual functions occurs during the 
waking state, it becomes delirium. That this delirium is 
analogous to the perturbed state of the imagination during 
sleep, appears from the delirium in fevers uniformly showing 
its approach in the patient’s slumbers only. It is a disposition 
to form false images and associations, which, in the begin- 
ning, the excitement of the outward senses has power to coun- 
teract, insomuch that a patient can be roused from delirium as 
he can be roused from sleep; but, by and by, the external 
senses lose their superiority, and their excitement is attended 
with unusual associations; they no longer convey impressions 
to the intellect, but become subservient to, and modified by it, 
and the judgment, w hich depends on the due balance of memo- 
ry and imagination, is lost. In fever, the delirium is tran- 
sitory ; in low fevers, it is combined with a comatose state. In 
melancholy, the delirium runs upon one object chiefly, or 
trains of ideas, which refer to the patient’s health and corpo- 
real feelings. In madness, the variety is infinite; but chiefly 
consisting in a vitiated imagination and perverted judgment, 
with fierceness and increased power of corporeal exertion. 
There are five organs peculiarly adapted to convey sensa- 
tions to the mind; or, as I am more inclined to say, to rouse 
the faculties of the mind by exercising the internal organs of 
the senses in the brain; these may be considered as forming 
a medium of communication betwixt the external creation 
and the sentient principle within us; they are at the same 
time the bond of union betwixt sentient beings. These organs 
are called the external senses; viz. the sense of seeing, 
the sense of hearing, the sense of smelling, the sense of tast- 
ing, and the sense of touch. Was I willing to break in upon 
received opinions in an elementary book, I would say that 
there was a sixth sense, the most important of all, the sense of 
motion ; for it is by a sense of motion that we know many of 
the qualities of outward things, as their distance, shape, resist- 
ance, and weight. Individually, these organs convey little in- 
formation to the mind; but by comparison and combination, 
the simple and original affection or feelings received from 
them are associated and combined to infinity, and administer 
to the memory and imagination, to taste, reasoning and moral 
perception, the passions and affections, and every active power 
of the soul, 8 
BOOK I. 
OF THE EYE. 
CHAP. I. 
INTRODUCTORY VIEW OF THE PRINCIPLES OF OPTICS. 
Light is a matter thrown out from ignited, or reflected 
from shining, surfaces ; and which enters the eye, and impress- 
ed on that organ, gives the sensation of sight. The sun is the 
greatest source of light, and perhaps the original and only 
soui'ce. The minuteness and inconceivable velocity of light, 
the facility with which it penetrates bodies of the greatest 
density and closest texture, without a change of its original 
properties, makes it the source of the most wonderful and 
astonishing phenomena in the physical world. 
The smallest stream of light which propagates itself through 
a minute hole, is called a ray; and, as rays of light pass through 
a uniform medium in a straight course, they are represented 
by mathematical lines. But light is not uniform in respect of 
colour; every part of a ray is not capable of exciting the idea 
of whiteness which the whole raises. White light is composed 
of different kinds of rays, which individually give the sensa- 
tion ; one of red, another of orange, a third of yellow, a fourth 
of green, a fifth of light blue, a sixth of indigo, and a seventh of 
a violet or purple.* These are named the prismatic colours ; 
because, in the spectrum produced by making a ray of light to 
pass through a prism, these several colours are seen in the 
succession in which they'are above enumerated. Each of 
these rays individually impresses the eye with its own colour; 
but when they all impress the eye at once, the sensation upon 
the organ of sight is a compound effect; no individual colour 
* There is a fact not a little extraordinary regarding the emanation of rays 
from the sun, and which has been discovered in the present day, viz. that 
there are invisible rays, giving heat but no light, which are less refractable 
than the coloured rays; and that all rays, in proportion to their refrangibility, 
have less power of producing heat. See Herschel on the invisible rays oi 
iight. Phys. Trans, 1800, part ii. p. 284, ®F THE EYE. 
9 
is presented, but that mixed light which is called whiteness, 
and which may be divided into its individual colours by pass- 
ing it through a prism. 
It is the nature of most bodies to absorb some of these rays 
of light and to reflect others from their surface; consequently, 
the colours of bodies depend upon the particular rays which 
are reflected from them, or upon the combination of such rays 
as are reflected from them; and a body appears of that colour 
of which the light coming from it is chiefly composed. 
When a ray of light passes from a rarer to a denser medium, 
or from a denser into a rarer, it alters its course, if there be any 
obliquity in the original direction; but if it strikes from one 
medium to another perpendicularly into the surfaces, its origi- 
nal direction is not changed. If the ray passing from the air 
enters obliquely into glass or water, or any denser medium, it 
turns more towards the perpendicular; but if it passes through 
the glass and emerges again into the air, it resumes its original 
direction, diverging from the perpendicular. This effect of 
different mediums upon the ray of light, is called refraction; 
when a ray of light impinging upon a surface does not enter, it 
rises again to the angle of its incidence : and this is reflection. 
The prism is a piece of glass of a triangular form ; the in- 
clined surfaces of which, when placed in the course of the ray 
of light, refract, and separate the several parts of the hetero- 
geneous ray, and show its compound nature. If the sun be 
permitted to shine into a dark room through a small hole in 
the window-shutter, and the beam of light be made to fall upon 
a glass prism, it is, in passing through the glass, separated into 
Its constituent parts ; because the several coloured rays have 
different degrees of refrangibility, in the order in which I have 
already enumerated them. If the rays, after passing through 
the prism, be made to pass also through a convex glass, they 
are brought again to a point in the focus of that glass; and the 
effect of the whole colours thus re-united, is perfect whiteness. 
We might suspect that the beams of light xvere homogeneous, 
and that the degree of refraction gave different colours to the 
rays, were it not proved, that how much soever any of the co- 
loured rays is further refracted, it does not change its nature: 
nor will rays suffer any change by reflection from bodies of dif- 
ferent colours, for minium will appear yellow, green, blue, &c. 
according to the colour of the ray of light directed upon it.* 
* It is found, that the coloured rays have not all the same power of illumi - 
nating objects ; the orange ray possesses this property more than the red ; the 
yellow more than the orange, &c.; and the maximum of illumination lies in 
the brightest yellow or palest green ; nor do the several rays equally affect 
the thermometer. See Herschel’s Exp. Phys. Trans. 1800, p. ii. p. 255 10 
OF THE EYE. 
As the impression of light remains some time upon the 
nerve of the eye, it gave Sir Isaac Newton the opportunity of 
examining, whether each coloured ray makes a distinct im- 
pression on the eye, or whether they so affect each other as 
to impress the sense of whiteness on the eye. When a burn- 
ing coal is whirled in a circle the eye perceives an entire 
circle of fire, because the impression made by the coal in any 
point of the circle remains until the coal returns again to the 
same place, and renews the sensation. When all the varieties 
of colours are painted in a circle, and turned in the same way 
with the burning coal, they must each make their separate im- 
pression upon the optic nerve; but the general sensation is 
whiteness ; or when the teeth of a comb are drawn across the 
stream of light issuing from a prism, the different colours are 
intercepted in such quick succession, that a perfect whiteness 
is the result of the mixture of impressions. There are many 
experiments which show that the inequalities of the refraction 
of light are not casual; that they do not depend upon any 
irregularity of the glass : on the contrary, it is proved, that 
every ray of the sun has its own peculiar degree of refrangi- 
bility, according to which it is more or less refracted in pass- 
ing through pellucid substances, and always in the same man- 
ner : and, lastly, that the rays are not split and multiplied by 
the prism. 
When a ray of light falls upon the surface of glass obliquely 
it inclines to a line drawn (through the point of incidence) 
perpendicular to the surface. 
Fiy.l. 
Frg.2. 
Thus the ray A, fig. 1, proceeding from the object, *, is 
refracted upon entering the mass of glass in the direction B, 
having a tendency towards the perpendicular line. By this 
means, if a number of rays proceeding from any one point, as 
in fig. 2, fall on a convex or spherical'surface of glass, they 
will be inflected so as to gather about the perpendicular line OF THE EYE. 
11 
a A in the centre of the glass : which perpendicular line is the 
axis of the glass. If the rays of light proceeding from an object 
be made to strike into a mass of glass with a concave surface, 
the obliquity with which they impinge upon the surface, being 
the reverse of the convex surface, they are not made to con- 
verge upon the central line, but diverge from it. 
Farther, the rays of the sun, when passing from a medium of 
glass into the air, are turned, by refraction, farther olf from 
the central line to which they were drawn in entering the 
convex surface of glass. But if the rays, in passing through 
the glass, were in a direction converging to the perpendicular 
line, they will be made to converge still farther, as is seen 
here in fig. 3. 
Fig. 2. 
Fig. 4. 
If, however, the rays be made to pass from glass into the 
air, and the surface of the glass be concave, 'as in fig. 4, the 
rays will be made to have a less 
degree of convergence, so as 
to remove the image * farther 
from the surface of the glass. 
But if the rays passing through 
the medium of glass have no 
convergence, but pass in parallel 
lines, they will diverge as the 
lines a a, fig. 4. do, when they 
emerge from the concave surface 
of the glass. 
We see, then, the operation 
of a double convex glass, in 
forming the image of a luminous 
body upon a surface. If, for 
example, such a glass be held 
between a candle and a piece 
of white paper, (the distances 
being properly adjusted,) the 
image of the candle will appear 
distinctly upon the opposed 
Fig. 5. 12 
OF THE EYE. 
surface, but inverted; because the rays coming from the 
point A fig. 5, converge at c, and those from the point b at d. 
Before proceeding farther in this short exposition of the 
principles of optics, it will be necessary to take a very slight 
view of the structure of the eye. 
INTRODUCTORY VIEW OF THE STRUCTURE OF THE EYE. 
It is the first principle of the constitution of the eye, that 
the rays of light must be so concentrated as to impinge strongly 
on the expanded nerve or retina in the bottom of the eye. 
Now, as we have seen that a lens (which is a double convex 
glass) is necessary, so to concentrate the rays of light proceed- 
ing from an object, as to form a small and lively image of it 
(as in marginal plate, fig. 5.) so, in the same manner, an essen- 
tial part of the eye is the lens, which brings the rays of light 
to a focus ; and that the lens may make the rays proceeding 
from an object converge into an accurate focus, so as to form 
a distinct image on the eye, the vitreous humour is interposed 
betwixt the lens and the surface of the retina : again, it is 
necessary to the constitution of the eye, that, in order to 
increase the sphere of vision, the anterior part of it shall pro- 
ject and form a large segment of a small circle, so as to take a 
greater circumfei'ence into the sphere of vision than could have 
been done, had the larger sphere of the eyeball been conti- 
nued on the forepart. Another necessary part of the apparatus 
of the eye is the iris, which is a curtain in the anterior chamber 
of the eye, perforated with a hole, which is capable of being 
enlarged or diminished so as to admit a larger or smaller 
stream of light according to the intensity of the light. In this 
provision, we see the necessity of the anterior humour of the 
eye being different from the others; being merely an aqueous 
secretion, while the others possess a degree of firmness, viz. 
that the iris or curtain of the eye, may move with perfect free- 
dom in it. 
Fiff.ff. OF THE EYE. 
13 
The three humours of the eye are thus situated, and have 
this general character : 
1. The aqueous humour is the anterior humour of the eye. 
It distends the anterior and pellucid part of eye, so as to 
increase the sphere of vision. It is perfectly fluid, and of a 
watery consistence, that it may allow free motion to the iris. 
2. The lens or chrystalline humour is placed immedi- 
ately behind the perforation in the iris ; which perforation is 
called the pupil. The lens collects the rays of light like a 
double convex glass, so as to concentrate them, and make a 
more forcible image on the bottom of the eye. 
3. The vitreous humour is behind the lens. It distends 
the general ball of the eye into a regular sphere, that it may 
move easily in the orbit; and its diameter in the axis of the 
eye is so proportioned to the focal distance of the lens (affected 
also in some degree by the other humours) that the image of 
an object is formed accurately on the surface of the retina ; 
accordingly, when the coats are cut from the back of the eye, 
the picture of a luminous object held before the pupil is seen 
exquisitely minute and distinct on the botom of the eye. 
While these humours have each its distinct character, they 
possess in proportion to their density, different powers of re- 
fracting the rays of light. This has the still farther good effect 
of correcting the aberration of 
the rays, and giving the truest 
colours, as well as the most 
correct image of the object 
presented to the eye. 
If the lucid anterior part 
of the eye be formed too pro- 
minent, or if the lens of the 
eye have too great a degree 
of convexity, or, lastly, if the 
size of the ball of the eye, and 
the diameter of the vitreous 
humour in the axis of the eye 
be unusually great, then the 
person does wot see distinctly ; 
because the powers of the hu- 
mours, in concentrating the 
rays of light, are too great, 
and the image of the object is 
not formed accurately on the 
retina', but before it. Thus, in fig. 7. the convexity of the 
cornea, the lucid anterior part of the eye, or the focal powers 
Fm 
Bg.S, 14 
of the lens, being too great for the length of the axis of the 
eye, the image is formed at a before the rays reach the sur- 
face of the retina ; and alter coming accurately to the point, 
they again begin to diverge ; which diverging rays, striking 
the surface of the retina, give the indistinct vision of a near- 
sighted person. But as this indistinctness of vision proceeds 
from no opacity, but only the disproportion of the convexity 
of the eye to the diameter, the defect is corrected by the con- 
cave glass, a, fig. 8 ; for the effect of this glass being the re- 
verse of the convex, it causes the rays to fall upon the surface 
of the eye, so far diverging from the perpendicular line, (which 
is exemplified in fig. 1.) as to correct the too great conver- 
gence caused by the convexity of the humours. But, when a 
near-sighted person has brought the object near enough to the 
eye to see it distinctly, he sees more minutely, and, conse- 
quently, more clearly ; because he sees the object larger, and 
as a person with a common eye does, when assisted, with a 
magnifying glass or convex lens. 
The near-sighted person sees distant objects indistinctly ; 
and as the eye, in consequence, rests with less accuracy upon 
the surrounding objects, the piercing look of the eye is dimi- 
nished, and it has a dulness and heaviness of aspect. Again, 
the near-sighted person knits his eyebrows, and half closes his 
eyelids : this he does to change the direction of the rays, and 
to correct the inaccuracy of* the image, in a manner which may 
be understood by the following analogy. If we make a card 
approach a stream of light passing through a window, it will 
so attract the rays of light, as to extend the margin of the figure 
of the circular spot of light upon the wall. In the same way, 
when a stream of light, proceeding from an object towards the 
eye, is made to pass through a small hole, the circular margin 
of the hole so attracts the rays, as to produce the same effect 
with the concave glass ; by causing the rays to take a direction 
outward, as if proceeding from a nearer object, the image is 
carried farther back from the lens ; and when a near-sighted 
person peers through his eyelids, it makes the rays impinge 
accurately upon the tetina.* 
The effect of old age, is gradually to reduce the eye to a 
OF THE EYE. 
* Short-sightedness may be produced by accidents. Once I have known it 
produced by a piece of glass sticking in the cornea, and causing great inflam- 
mation. Dr. Briggs mentions the case of an old man, who had long used 
spectacles, becoming suddenly short-sighted by catching cold, and he was af- 
terwards enabled to read the smallest print without glasses. In general, how- 
ever, it is by some accident, and often not till manhood, that we become sen- 
sible of being short-sighted.; and, then men are very apt to attribute the de- 
fect to some particular occurrence. OF THE EYE. 
15 
less prominent state, and, consequently, to bring it to the 
reverse of the near-sighted eye. 
From the decrease of the hu- 
mours, and the lessened convexity 
of the cornea, the image of objects 
is not formed soon enough to im- 
pinge accurately on the retina, the 
rays tend to form the image behind 
the retina, as we see in fig. 9. 
In this figure, we have the effect 
of old age on the humours represent- 
ed : without the intervention of the 
glass A, the rays have a direction 
which would form the image at 
some distance beyond the retina, as 
at b. But by the convex glass a 
(which is of the nature of the com- 
mon spectacles for old people) the 
direction of the rays of light is so 
corrected, that the image falls accu- 
rately on the bottom of the eye. 
We understand, then, whence these opposite defects of sight 
arise ; that, in old people, objects cannot be seen distinctly 
when near, and, in short-sighted people, they cannot be seen 
distinctly when at a distance. We see, also, why old age cor- 
rects short-sightedness by gradually reducing the convexity of 
the eye, enabling the person to see objects farther removed, 
until, by degrees, he comes to see perfectly at the distance 
most convenient for the common affairs of life.' 
It has been, by some, thought extremely difficult to ac- 
count for the image appearing to us, as it is in nature, erect, 
since it is actually figured on the bottom of the eye in an in- 
verted posture ; but the terms above and below have no rela- 
tion to the image in the bottom of the eye, but to the position 
of our bodies and the surrounding things. When I look to a 
tall man’s face, I direct my eyes upwards ; I observe his situa- 
tion, as it relates to an ideal area before my eyes, or to a 
space in the sphere of vision. 
When an object approaches towards the eye, the dia- 
meter of the picture on the retina increases in the same 
proportion as the distance between the eye and the object 
decreases : and, consequently, it decreases in the same pro- 
portion as the distance increases. But the degree of bright- 
ness of the picture of an object on the retina continues the 
same at all distances, between the eye and the object, unless 
some of the rays of light are interrupted in their progress; for, 
'F&S- 16 
or THE EYE. 
as the advancing object becomes bright, it increases doubly in 
length and breadth, or quadruply in surface. The faint ap- 
pearance of remote objects, therefore, is occasioned by the im- 
perfect transparency of the atmosphere. 
There is nothing more astonishing in the structure of the 
eye, than the sensibility of the expanded nerve, as proved by 
the extent of the changes or degrees of light which illuminate 
visible objects ; or the great degree of light which the eye can 
bear, and the low degree of light at which objects are visible. 
Thus, the proportion betwixt the degrees of light illuminating 
an object by the sun, and by the moon, at any equal altitudes, 
is calculated at 90,000 to 1.* Again, by M. de la Hire’s cal- 
culation, we see the sail of a wind-mill, six feet in diameter, 
at the distance of 4000 toises. The eye being supposed to 
be an inch in diameter, the picture of this sail, at the bottom, 
of the eye, will be of an inch, which is the 666th part of a 
line, and is about the 66th part of a common hair. This 
gives us an idea of the minuteness of the structure of the op- 
tic nerve, and the extent in the degree of impression of which 
it is susceptible. It is evident that some guard to the eye 
must be furnished, in .order that the organ may accommodate 
itself to this variety in the intensity of impression. 
The pupil ol the eye is formed by the central perforation in 
the iris or curtain, which hangs before the lens. This body 
having muscularity, is moveable ; it dilates or contracts the 
hole or pupil, transmitting the rays so as to adapt the diame- 
ter of the stream of light, darting into the eye, to the intensity 
or degree of light. If a body is illuminated but faintlv, the 
pupil is (insensibly to us) enlarged, and a greater quantity of 
the rays are allowed to be transmitted to the retina. But as 
the convexity of the pellucid part of the eye, and the concen- 
trating powers of the lens, remain the same, the size of the 
image is not altered by this dilatation of the pupil, but only the 
strength of the image or picture in the bottom of the eye is 
increased. 
We understand that the rays of light are refracted, when 
they pass out of one medium into another of different density. 
For example, the rays of light are refracted towards the per- 
pendicular line, when they enter the cornea of the human eye ; 
but they will be refracted in a very small degree in entering the 
cornea of fish, because the aqueous humour is of the same 
density with the fluid from which the rays of light are trans- 
mitted ; accordingly, the cornea of fishes is not prominent: 
this would limit their sphere of vision, were not the flatness of 
the cornea counteracted by the prominence of the whole eye. 
* See Smith’s Optics, vol. i.p. 29 OF THE EYE. 
17 
and the more anterior situation of the chrystalline lens ; a 
large pupil and long diameter of the eye we shall afterwards 
find to be necessary to the distinct vision of fishes.* 
It is natural, on the present occasion, to inquire into the 
effects of the several humours of the eye, in producing in 
those who are short-sighted the obscurity arising from the dou- 
ble appearance of small and shining*points. This is prettily 
explained in Jurin, upon Sir Isaac Newton’s principle, con- 
cerning the fits of easy refraction and reflection of light. 
The horns of the new moon, or the top of a distant spire, or 
the lines upon the face of a clock, appear double or triple, and 
sometimes much more multiplied, to a short-sighted person, 
The same appearance will be given when an object is held too 
near the eye, for perfect vision. If the light is seen through a 
narrow slit in a board, and the board is brought nearer to the 
eye than the point of distinct vision, the aperture will appear 
double, or as two luminous lines, with a dark line between 
them ; and as the distance is varied, two, three, four, or five 
dark and luminous lines will be observed. There are many 
such deceptions in viewing luminous bodies ; all of them pro- 
ceed from the same cause, which is this :—Before Sir Isaac 
Newton’s philosophy was acknowledged, it was the received 
opinion, that light was reflected from the surface of bodies by 
its impinging against their solid parts, and rebounding from 
them like a tennis-ball when struck against a hard and resisting 
surface: further, as they saw that part of the rays of light 
were in glass reflected, and the rest transmitted, they conceiv- 
ed that part entered the pores of the glass and part impinged 
upon its solid parts. But this does not account for the re- 
fractions which take place when the rays have passed the 
glass, and are about to be transmitted into the air; they can- 
not find solid parts to strike against in entering the air, for the 
refraction of the light is greater in passing from the glass into 
the air, than from the air into the glass ; and if water be 
placed behind the glass, the refraction of rays passing out from 
the glass is not increased, but diminished, by this substitute for 
the rarer medium of the air. Again, when two glasses touch 
each other, no refraction is made in rays passing from the one 
into the other. To explain this, Sir Isaac Newton taught, 
* Neither fish out of water, nor other animals within water, can see any 
object distinctly. Divers see objects as an old man would do through a ve- 
ry concave glass put near to the eye ; and it has been found that the convexity 
of spectacles for divers in the sea must be that of a double convex glass, equal 
on both sides to the convexity of the cornea. The necessity of this is plain ; 
the aqueous humour of the eye being of the same density with the water, 
there is no refraction of the rays in passing from the water intq the eye, and 
his deficiency must be supplied. 18 
OF THE EYE. 
that in the progress of rays of light, there is an alternation of 
fits of easy transition or reflection ; or, in other words, that 
there is a change of disposition in the rays, to be either trans- 
mitted by refraction, or to be reflected by the surface of a 
transparent medium. Jurin illustrates this opinion, and its ap- 
plication to our present purpose, in this manner. 
Suppose that a b d, and b d f, 
are mediums of different densi- 
ty, and that their surfaces are 
intersected by the line b d ; a- 
gain, let A be a pencil of rays, 
which, issuing from this point 
falls upon b a d, as the refract- 
ing surface B a n is convex, and 
no two points of it, from a to d, 
are equally distant from the 
source of the rays A ; and as the 
rays of light, in their progress, 
alter alternately from the fit of 
refraction to the fit of reflec- 
tion, they must be in part re- 
fracted to the focu,s f, and re- 
flected in the direction of the 
dotted lines c e. Thus, if the 
ray A a happens to be in dispo- 
sition to pass through the me- 
dium b d f, it will pass on to- 
wards the point F. If the next 
ray A b should be in no fit to be 
transmitted, because, being in 
a degree farther advanced from 
its source a, it has changed to 
the fit of reflection, then it will 
not be refracted towards ‘the fo- 
cus f, but reflected off towards 
c ; but again the ray a d being advanced farther from it - 
source, it will impinge upon the surface b d, during its dispo 
sition to refraction, and will concentrate its beams at f ; and so 
with all the others, alternately reflected and refracted. 
The consequence of this obstruction to the equal refraction 
of light is, that the image formed at f is feeble ; but still it is 
distinct and perfect; because the transmitted rays are regularly 
concentrated, and form the proper focus. But if the con- 
verging rays should be received upon a plain before they ar- 
rive at the focus r, the reflected rays of light will have left 
spaces dark where they would have fallen by refraction, and. 
JT/j.io. OF THE EYE. 
19 
consequently, distinct luminous circles will be thrown on the 
plain : again, if the plain surface be opposed to the rays, after 
they have formed their focus, and are again dispersing after 
having crossed, the same unequal effect of light and dark cir- 
cles will be thrown on it; though now, the rays of the right 
side of the pencil b d f, will form the left of the pencil fgh. 
How the changeable 
state of the rays produ- 
ces the indistinctness of 
the near-sighted eye, 
may be understood from 
this (11.) diagram.— 
the rays a strike 
the convex surface of the 
cornea, part of them will 
be reflected from the sur- 
face of the cornea, in the 
direction of the lines b 
b, when they will conse- 
quently strike upon the 
convex surface of the 
lens in luminous rings, 
these rings will be still 
farther multiplied and 
diminished in diameter, 
in being in part trans- 
mitted, in part reflected, from the surface of the lens c, and 
vitreous humour d d. These effects of the alternate disposi- 
tion of the rays for transmission and reflection would not be 
perceptible, did the converging powers of the cornea and lens 
bring the focus of the rays exactly to the surface of the re- 
tina ; but as the focus is formed at e, some way before the re- 
tina, the rays have decussated and spread out again before they 
form the image upon the bottom of the eye. Instead, there- 
fore, of forming an accurate image, they are spread out into 
concentric circles ; or in a lesser degree, the person experi- 
ences a confused outline of the object, which becomes sur- 
rounded with several rimrs or false outlines.'* 
Fig. 11. 
* By fits of easy transition, it was not meant by Sir Isaac Newton that the rays . 
must necessarily be transmitted through every pellucid medium, and at any 
obliquity of incidence, but only that the ray was more easily transmitted, and"*- 
more difficultly reflected; nor was it meant that, during itsJit of easy reflection, 
it was absolutely incapable of being transmitted, but only more readily re- 
flected than transmitted. 20 
CHAP. II.' 
OF THE COATS OF THE EYE. 
The coats of the eye are to be divided into three classes. 
1. The anterior and external coats, viz. The conjunctiva 
and the albuginea. 
2. The proper coats, viz. The scler.otica, the choroides, 
the RETINA. I 
3. The transparent tunics of the eye. 
As the first class belongs to the external apparatus of the 
eye, we shall begin with the proper coats. 
Speaking generally, and without considering the minuter 
divisions of anatomists, we may say, that there are three pro- 
per coats of the eye, viz. the sclerotic coat, giving strength; 
the choroid coat, being the vehicle of the chief vascular 
structure of the eye ; and the retina, or expanded nerve, be- 
ing the organ itself. These are the proper coats of the eye, 
Although many of these coats may be capable of being di- 
vided by the art of the anatomist, either by the knife, by injec- 
tions, which form extravasation between their layers, by mace- 
ration, or by the chemical action of fluids ; yet it is better, in 
a general enumeration, to take a natural division and charac- 
ter, than to enumerate their several lamina. 
OF THE SCLEROTIC COAT. 
The sclerotic coat is so called from its hardness.* The 
sclerotica and cornea are often considered as one continued 
coat investing the eye ; hence they say, the opaque and the 
lucid cornea. But, although these parts are actually in union, 
yet as they are really of so very different a nature, we must 
consider them apart, and treat at present only of the opaque 
white sclerotic coat. 
The sclerotic coat is a strong, firm, and white membrane, 
consisting of lamellae firmly attached and interwoven, and not 
capable of being regularly separated by maceration ; it has the 
denseness of tanned leather. In firmness, whiteness, opacity, 
and the little appearance of vascularity, it more resembles, the 
dura mater, than any other membrane of the body. 
In adults, the sclerotic coat is stronger and firmer, compara- 
tively, than in the foetus; the cornea less so. On the outer 
* Dura seu sclerotica; Vesalius, Ruysch, &c. OF THE COATS OF THE EYE. 
21 
surface, it has (towards the orbit) a loose cellular membrane 
attached to it, which allows the motion of the eyeball. Upon 
the fore part it is invested by the tunica albuginea or tendinea. 
Upon its inner surface, it has a loose and soft membrane which 
connects it with the choroid coat. 
In birds, and the tortoise, the posterior part of the sclerotic 
coat is thin; the fore part of it is split into laminae, betwixt which 
there are interposed thin plates of bone,* while in fishes it is 
in part cartilaginous,! but thin and transparent, so that there 
appears a very beautiful spotted coat beneath it. There are 
also seen in the sclerotic of fishes little white granules like glands. 
The vagina of the optic nerve can be separated into two 
laminae;! the outer one is observed to unite intimately with 
the outer part of the sclerotic coat, while the inner lamina of 
the vagina is contiguous with its inner surface. The pia mater, 
too, says Zinn, when it has pierced the foramen in the sclero- 
tic coat, along with the substance of the nerve, expands upon 
the inner surface of this coat, and extends even to the cornea, 
and forms one of its intimate laminae. This must be only that 
part of the pia mater which invests the optic nerve, or, more 
strictly speaking, that membrane which stands in the same 
relation to the nerve, that the arachnoid coat does to the brain; 
for the membrane, which sinks into intimate union with the 
nerve, accompanies it even in forming the retina.§ 
The sclerotic coat is the great support of the globular figure 
of the eye; it defends the more delicate internal structure from 
slighter injuries, by its strength ; and from the progress of in- 
flammation, by being of a structure but little vascular, and not 
prone to disease. That inflammation which we see to be so 
frequent in the eye, is not in the sclerotica, but in the adventi- 
tious coat, the conjunctiva. But in proportion as the sclerotic 
* Cuvier, vol. i. p. 387. 
f Morgagni Epist. An. xvi. 40. Cuvier, 388. 
t Ruysch, Zinn. 
§ It may be well, in this place, to mention the opinions of the chief supporter 
of that scheme of the coats of the eye, which derives them all from the invest- 
ing membranes of the brain and optic nerve. M. le Cat, in his Traite des Sens, 
describes them thus:—When the optic nerve has entered the orbit, the dura 
mater which surrounds it, splits into two laminx; the external one attaches to 
the orbit, and forms the periosteum, the other forms the vagina of the nerve. In 
the angle formed by these, the muscles of the eye arise. This continued sheath 
of the nerve (he continues) expands into the globe of the eye, as the mass of 
glass is blown into a bottle. The dura mater of the nerve is expanded into the 
cornea (viz. sclerotica.) The second envelope, or pia mater, forms two laminae; 
the one is applied to the sclerotic coat, and the other forms the choroid coat. 
The choroid coat divides anteriorly, and forms the iris and ciliary processes. 
The internal medullary part of the optic nerve forms the retina. Finally, 
“ L’oeil est tres evidemment l’extremitd nerveuse epanouie boursouflee en 
bouton creux & plen de liqueurs,” p. 158. See also Bonn Sandifort Thesaur, 
de continuatione membraine. 22 
OF THE COATS OF THE EYE, 
coat resists pressure and the progress of disease from without, 
it resists the swelling of the parts within when they become:' 
diseased, and gives the greatest torture. 
Of what importance the entireness of the coats, and the 
uniform resistance of the humours of the eye is to the healthy 
state of the organ, will be afterwards examined. 
OF THE CORNEA. 
The cornea is so called, from being firm, transparent, and 
composed of laminae.* It is the pellucid circle on the fore 
part of the eye, which seems variegated with colours ; though 
this is a deception, owing to its perfect transparenc)’. The 
circle of the cornea is, however, far from being regular ; its 
margin is flat towards the nose. 
The cornea consists of laminae ; betwixt which, there is in- 
terposed a cellular substance, filled with a perfectly pellucid 
fluid.f These cells seem, like the common cellular membrane 
of the body, to have a free communication with each other, so 
that the fluid freely exudes, and as quickly is imbibed by ma- 
ceration. The fulness of the cornea, with the perfect transpa- 
rency of the fluid, gives a brilliancy to the eye, and is a sign of 
health ; the reverse dims the eye, and with the fallen features, 
accompanies ill health. Sieno observed, and Petit confirmed, 
the fact,:): that the pores on the surface of the cornea exuded 
the fluid which fills the cells of the cornea ; and that, after rhe 
surface was carefully dried by pressure, the moisture might be 
seen to form in drops upon the surface. The moisture can be 
thus forced out from the pores of either surface of the cornea.(jv 
This moisture becomes dull and clammy on the approach ol 
death, and forms sometimes a pelicle over the cornea. The 
laxity with which the laminae of the cornea are connected 
may be, in some measure, demonstrated, by taking it be- 
twixt the finger and the thumb ; we shall then find, that the 
layers can be made to glide very freely on each other. In 
the foetus, and in young children, the cornea is of great thick- 
ness, and resists the point of the lancet or scissors. This re- 
sistance in the foetus proceeds from a great degree of tough- 
ness, while, in the adult, the surface of the cornea is so hard, 
that I have often seen the point of the knife, in extracting the 
cataract, bend upon it. This turning of the elastic point ol the 
knife is very apt to give a wrong direction to the incision ; 
and, indeed, this occurred to me in my first operation. 
* “Cornumodo, dura, Sc cornu instar in laminasdividareque potest.” Vesalius 
I Substantia spongiosa Valsalvae. 
i See also Hovius, p. 82* §Zinn. ®F THE COATS OF THE EYE. 
23 
There is a pelicle, or exceedingly thin coat, which, by ma- 
ceration, can be taken off from the surface of the cornea. This 
is the conjunctiva continued over it. 
The membrane in fishes, analogous to the adnata, lies loose 
over the cornea; and, in serpents, it is thrown' off from the 
cornea, with the scales of the body, and remains attached to 
the cast skin of the head; and in the foetus calf, I have forced 
the blood in the vessels of the conjunctiva into the Vessels 
passing over the surface of the cornea. 
By maceration, I have found, raised in the fluid, a very deli- 
cate and transparent membrane from the inner surface of the 
cornea;* and, after long continued soaking, the whole cornea 
can be taken out of the sclerotic coat, like an optician’s glass 
from its frame. 
The cornea possesses great sensibility; although much of 
the pain, from hard bodies flying into the eye, is to be attri- 
buted to the motion of the eyelids, and the great sensibility 
with which they are endued. When a splinter of glass or metal 
strikes and sticks in the cornea, inflammation is excited; in 
consequence of this, vessels carrying red blood strike into it, 
or shoot over its surface in a new film of membrane.f Petit 
thought he observed first in a negro, and afterwards in a variety 
of instances, red lines in the cornea; which he conceived to 
be the anastomosing of vessels. There are, besides, says he, 
many circumstances which argue that there are blood-vessels 
in the cornea. When the eye receives a stroke, there is often 
blood effused in its substance ; abscesses, also, are found with- 
in it, and phlyctsenae are seen on its surface; and in great inflam- 
mation of the eye, the cornea appears red; which, he supposed, 
must he produced by the same cause, which makes the albu- 
ginea red, viz. the enlargement of its vessels, and the circulation 
of red blood. But we must not imagine, he continues, that, in 
the natural state, red blood circulates in the cornea ; for the 
vessels are not to be seen with the microscope; nor are they 
penetrated by injection ; nor do they appear in the feetus ; nor, 
when little abscesses are formed in the cornea ; but only when 
violence has been done by a stroke upon the eye. In an eye 
in which the tunica conjunctiva was most minutely injected, as 
well as the internal vessels of the eye, I had resolved carefully 
to examine the structure of the cornea; and after a long mace- 
* This, within these two years, lias been claimed as a discovery. I fear that 
this must be considered as the capsule of the aqueous humour, long since 
described. 
f I have found the spark from iron, in blacksmiths and masons, buried in 
the cornea for several days (some authors say months,) without exciting pain 
or much inconvenience. I have also more than once picked a little black 
slough from the cornea, mistaking it for a piece of iron, when it was only the 
consequence of the iniurv, 24 
OF THE COATS OF THE EYE. 
ration, in which it had greatly swelled, 1 observed a set of 
vessels totally distinct from the extremities of the minute blood- 
vessels. The minute blood-vessels which were injected, stopt 
abruptly on the margin of the cornea. But these I now mention 
are particular; they are in great profusion, large, and perfectly 
pellucid; they are large towards the middle of the cornea, and 
diminish towards the margin. Their freecommunicationformed 
a net-work deep in the thickened substance of the cornea. The 
size, perfect pellucidness, and intimate connection of these 
vessels,migntperhaps incline one to call this a cellular structure. 
Vessels attach themselves both to the inner and to the outer 
surface of the cornea ; and when it becomes spongy and vas- 
cular in this way, little can be explained of its natural structure. 
Thus, the pannus and pterygium are membranes which stretch 
across and adhere to the cornea, while the iris frequently 
attaches to its inside. In this case, the cornea becomes spongy, 
thick, and vascular ; and, -when cut, there is red blood in it 
and in staphyloma,f the iris is generally attached to the cornea. 
I have a preparation in which the form and character of the 
iris is entirely lost; it is extended into a reticulated membrane 
which lines the surface of the extended cornea. 
OF THE CHOROID COAT. 
The choroid is the vascular tunic of the eye ; it is so called, 
from its resemblance to one of the membranes of the secun- 
dines. It is the middle coat of the eye, lying betwixt the 
sclerotic coat and retina. Injections show it to consist of two 
layers of cellular tissue; and it has upon its inner surface a 
pigment, which, being sometimes firm, might be taken for a 
membrane. It wTas Ruysch who observed this division of the 
choroid coat into two laminae ; and the inner one his son called 
the tunica Ruyschiana: but of these hereafter. 
Those anatomists who supposed the sclerotic coat to be the 
production of the dura mater, naturally concluded, that the 
choroid coat was derived from the pia mater ; and as Ruysch 
found it to be dividable into two laminae, so Sladius found the 
pia mater to consist of two membranes. It followed that the 
one lamina of the choroid coat was the continuation of the 
tunica arachnoides, and the other of the pia mater; but this 
account of these membranes has no support from observation. 
Pterygium, is a disease of the conjunctiva, but which resembles a mem- 
brane extended over the cornea from the canthus. Paxnus, is a disease of tlie 
same kind, but covering the cornea as with a white opaque membrane. 
t Staphyloma uvea, viz. a protrusion and opacity of the cornea; which, 
from the loss ot transparency and the general appearancij of the turftour, is 
supposed to resemble a grape. OF THE COATS OF THE ElrE. 
25 
Betwixt the pia mater and choroid coat there is no resem- 
blance ; the latter we shall find loaded with vessels : but these 
vessels are peculiar, and minister to a secreting surface. The 
pia mater in the brain, and optic nerve, is in strict union with 
the substance of the brain, and supports and nourishes it; but 
the choroid coat has no connection with the retina or expand- 
ed nerve. 
There can be no better mark of distinction between mem- 
branes than their degree of vascularity, and particularly in the 
manner of the distribution of their vessels. The choroid coat 
is most particular in the distribution of its arteries and veins. 
The great arterial vascularity of the choroid coat is to be seen 
only after a very minute injection, and the venous vascularity 
after artificial or accidental infarction of the blood, or by a suc- 
cessful injection from the superior cava although the very 
great vascularity of this coat was known to our oldest writers, 
yet the appearance of these vessels, when empty, has deceived 
many. Morgagnif and Maitre-jean have described fibres which 
they affirm to be distinct from the vessels, but which prove to 
be, in fact, the appearance presented by the collapsed vessels. 
The great peculiarity of the choroid coat, is its being a 
secreting membrane ; by which I mean, that the pigmentum 
nigrum which is applied to the medullary lamina of the retina, 
being a secretion, the choroid coat has necessarily that pecu- 
liar structure of vessels which belongs to the secreting mem- 
branes. This structure has enabled anatomists to tear it into 
laminae. For that part of the choroid coat next the sclerotic' 
is merely a vehicle of vessels and nerves, and is a tissue of 
them connected by very fine cellular membranes. The inter- 
nal part, again, is organized into a secreting surface, and is the 
tunica Ruyschiana.j: I conceive, that the division into the 
choroid coat, and tunica Ruyschiana, is warranted from the 
nature of the membrane, as the divisions of the coats of the 
intestines are.§ 
Morgagni says, that from his earliest youth, he had many 
proofs that the choroid coat wras not single in brutes ; he 
asserts, also, that Franciscus Sylvius and Guenellonius had de- 
monstrated the double laminae of this membrane before 
Ruysch.|j Certain it is, that Ruysch was not so fortunate in 
ascribing a use to this tunica Ruyschiana. He supposed that 
it gave strength to the choroid coat, and, by bringing a greater 
An observation of Walter. f Morg. Epist. Anat. xvii.2. 
.• Tiny sell. Epist. Anat. xiii. § Albini Annot. Acad, lib vii.cap. ir 
• Morgagni Epist. Anat. xvii. ” 26 
or the coats of the eye. 
afflux of arterial blood, supplied the necessary heat to the 
otherwise cold humours.* 
Tapetum.—The internal surface of the choroid coat has 
been long called tapetum, from its villous or fleecy appear- 
ance, when seen through the microscope. This surface in the 
adult is of a brown colour; in veny young subjects, it is red and 
bloody ; and, when minutely injected, it is like scarlet cloth. 
It is by this vascular surface or tapetum that the black pig- 
ment, which is laid under the expanded retina in the human 
eye, is secreted. 
The pigmentum nigrum.—The pigmentum jiigrum is the 
black or deep brown mucous substance which lies between 
the choroid coat and retina. It is of a nature to be washed 
away with a little water and a soft pencil.f This brown taint 
pervades the whole texture of the choroid coat. This matter 
is in immediate contact with the medullary pulp of the optic 
nerve. Its use is apparently to stifle the rays of light after 
they have impinged on the sensible surface of the retina ; for 
we know that blackness is owing to the absorption of the light, 
as whiteness and colour is the reflection of it from the surface 
of bodies. The dark colour of the secreted pigment of the 
choroid coat is, in some measure, peculiar to those animals 
which see in the brightest light of day ; but is wanting, or ol 
a bright reflecting green or silvery whiteness, in such as prowl 
by night. The natural conclusion, therefore, is, that the pig- 
mentum nigrum subdues the intensity of the impression, while 
the reflecting colours of the surface in animals which see in 
the night, strengthens the effect of the light on the surface ol 
the retina, by repelling it. As fishes have the other provisions 
for seeing in an obscure light, they have also this of the reflect- 
ing surface of the tapetum : as it is a secretion of the villous 
surface of the choroid, we see why it becomes somewhat defi- 
cient in old men, and sometimes wanting in the degenerate va- 
rieties of animals ; when entirely deficient, the blood circulat- 
* Quod ad ustim tunics Ruyschianae attinet crediderim hanc tunicam inte: 
ceteros usus esse destinatam, non solum ad robur clioroids, verum etiam ut a 
sanguinis arteriosi majori copia requesitus calor tribus humoribus natura fri- 
gidis conciliaretur. lluys. Respons. ad Christ. Wedelium, p. 14. 
f I cannot conceive how this matter should be confounded with the tape- 
turn or tapis, which, as the name implies, is the villous surface of the choroid 
coat. Tapetum is, properly, cloth wrought with various colours; and the 
analogy was first used by the French Academicians, in their account of the 
dissection of a lioness. “ The mejnbrane which is put into the bottom of the 
“ eye, and laid on the choroides, which we call the tapetum, was of an Isa- 
“ bella colour, intermixed with a greenish blue. It was easily separable from 
“ the choroides, which remained entire, with its ordinary thickness, after that 
“ we had taken away the membrane which forms the tapetum.” The expla- 
nation of this, I suppose, w ill be found in Morg. Epist. An, xyii. 3. OF THE COATS OF THE EYE. 
27 
ing in the vessels of the choroid coat gives a lurid redness to 
the reflections from the bottom of the eye.* 
Finally, in regard to the choroid coat, we have to understand 
that it consists of two laminse : the outer, and that which is 
next to the sclerotic coat, being the proper choroid; the in- 
ternal lamina, the tunica Ruyschiana : that on the 'surface of 
the tunica Ruyschiana, there is a pile or fleece, which is called 
tapetum : and lastly, that the secretion of this inner surface is 
a pigment, which, in the human eye, has the appropriate name 
of pigmentum nigrum ; but in many animals, it*is of a silver, 
golden, or Isabella colour; though, in my apprehension, the 
colour, in all these varieties, depends still upon a peculiar 
secreted matter. 
ANNULUS L1GAMENTOSUS. 
When we take away the sclerotic coat from the choroides, 
we see at the termination of the choroides forward in the iris, 
a white ring : this should be called the ciliary ligament: it is 
the bond of union betwixt the choroid coat, the iris, and co- 
rona ciliaris. Soemmerring calls this the annulus gangliformis 
tunicse choroidise. 
OF THE CILIARY PROCESSES, OR CORONA CILIARIS. 
The ciliary processes are formed of the anterior margin of 
the choroid coat; they give the appearance as if the choroid 
coat, at the anterior part, were folded inward to the margin of 
the chrystalline lens ; and, as if, to accommodate it to this 
sudden inflection, it had been plated, and not regularly con- 
tracted ; at least, this is much the appearance of the circle of 
ciliary processes, when, after cutting across the eye, we look 
from behind upon the lens in its natural situation. In this 
view, we find the pigmentum nigrum of the choroid coat con- 
tinued over the ciliary processes, which gives to them the ap - 
pearance of the regular plicse of the choroid coat, converging 
to the edge of the lens, and forming altogether a disk round it. 
When the black paint on the ciliary processes is a little 
washed away, and when we attentively examine this part, we 
find the ciliary processes to be actually little oblong plicse, 
* As the pigmentum nigrum is a secretion, we shall not be surprised to find 
it become deficient in the commencement of some diseases of the eye. This 
is known by the possibility of seeing to the bottom of the eye ; that is, the 
choroid coat becomes a reflecting surface, and throws out the beams like a 
cat’s eye. See Med. Obseri and Enquiries, vol. iii. p, 124. 28 
OF THE COATS OF THE EYE, 
which gradually arise from the choroid coat at the angle of its 
inflection, and terminate abruptly, approximating, but not at- 
tached to the margin of the lens. When the paint is washed 
entirely away, the whole circle of these processes appears evi- 
dently to be the continued choroid coat. 
When not injected, the ciliary processes are pale and loose ; 
but when minutely injected, they take a perfect scarlet colour: 
they resemble, in their uninjected state, the valvular-like 
doublings of the villous coat of the stomach and intestines. 
Before the choroid coat is inflected towards the lens, in the 
form of ciliary processes, it forms a firm adhesion to the sclero- 
tic coat near the circular margin of the cornea, and at the same 
time is united firmly to the root of the iris forming the annulus 
ligamentosus. From this, the processes tend inward, and a 
little backwards ; and are, at their external extremities, de- 
tached from the iris ; nor are they attached to the margin of 
the lens, but are loose and floating. . 
When the vitreous humour and lens fall out from the ante- 
rior segment of the eye, we find that the plicae or ciliary pro- 
cesses have left their impression on the anterior surface of the 
vitreous humour, and also on the intermediate expansion of 
the retina which extends before the membrane of the vitreous 
humour. This circular impression of the ciliary processes is 
called by Haller, striae retinae subjectae ligamento ciliari.* I 
have called this impression halo sign atus, because it is form- 
ed of a circle of radiations, formed by the impression of the 
ciliary processes, and is not peculiar to the retina, but the re- 
tina again makes its impression on the membrane of the vitre- 
ous humour. The furrows and doublings of the anterior part 
of the retina, formed by the impression of the ciliary pro- 
cesses, Dr. Monro has called the ciliary processes of the retina ; 
but, for my part, I think this a term likely to confound and 
mislead a student; and we might as well speak of the ciliary 
processes of the vitreous humour, or of the membrane of the 
vitreous humour, since they also take the impression of the 
ciliary processes.f 
When the vitreous humour and lens are taken out of the 
coats, we see also that the ciliary processes have left the stain 
of the fuliginous paint.! This it is necessary to remark, since I 
have seen students confound this mark with the ciliary pro- 
* Fascie vii. icon. ocul. 
f Winslow uses the term sulci ciliares, for the impression on the vitreous 
humour. Zinn calls this corona ciliaris, after Camper : he describes them 
well, p. 75. 
£ See Morgagni Epist. Anat. xvii. n 13. and Ruysch also, “ Nonnuli pro 
processu ciliari agnoscunt pullas pigmenti nigri reliquias, membranuloe tenuis- 
siroa; humoris cristallini & vitrei, &. quasi fibres mentientes, oculo sc. aperto, 
humoribusque exemptis; h?e autem nil sunt nisi avulsje particula: pigment'1 
nigri.” Ruysch. Thes. An. ii. Ass. I. No. xv. OF THE COATS OF THE EYE. 
29 
esses themselves. The ciliary processes are of a most elegant 
vascular structure. Their contorted arteries are beautifully 
represented in Zinn’s figure. He traces them from the ex- 
treme branches of the choroid coat; but, of their veins, he 
says nothing further than that they are continued from the 
branches of the vasa vorticosa, or veins of the choroid coat.. 
The points of the ciliary processes are not attached to the 
lens, but float loose in the posterior chamber of the aqueous 
humour;* but at a little distance from their points they ad- 
here to the fetina, where it is continued over the anterior part 
of the vitreous humour. Through this attachment only are 
they connected with the lens ; for, as we shall find presently, 
the retina (as a membrane, but not as the sensible retina) is 
continued over the chrystalline lens.f 
Soemmerring [leones oculi hiimani] describes the retina as 
spontaneously falling off and separating from the exterior cir- 
cle of the corona ciliaris. But he also has mistaken the nerv- 
©us matter which stops here for the whole retina. The trans- 
parent tunica vasculosa retinae proceeds to the lens. 
The ciliary processes, collectively, form a circle round the 
lens, which I call corona ciliaris: this circle forming a per- 
fectly opaque partition, which stifles all rays that might other- 
wise be transmitted by the side of the lens. The corona ciliaris, 
or ciliary circle, no doubt, serves at the same time as a connec- 
tion between the outer and strong coats of the eye and the trans- 
parent coats and humours ; for, it is to be observed, that ex- 
cepting, the connection which naturally exists between the 
optic nerve and retina, this slender hold which the ciliary 
processes take of the expanded retina, is the only attachment 
betwixt the humours of the eye and the proper coats. 
In regard to the names appropriated to this part of the eye, 
there is more confusion than it is possible to believe. It is 
necessary to attend to this ambiguous use of terms, else we 
shall be in danger of misunderstanding our best authors. Ve- 
salius considers the whole as a septum betwixt the vitreous and 
posterior chamber of the aqueous humour; but he seems to 
find much difficulty in giving it an appropriate name4 Fal- 
lopius and use the term corpus ciliare for the 
whole circle of the processes, and in the same sense that I have 
* This was demonstrated in a particular manner by Ruysch and Morgagni, 
t Zinn and other later writers have entertained the idea, that the adhesion 
of the ciliary processes to the membranes covering the vitreous humour is by 
a kind of gluing, rather than a union by cellular membrane. See Zinn, p. 75. 
■t “Neque mihi ullum occurrit nomen quod ipsi aptius indam quam tunics : 
aut si voles, interstitii vel scepti inter vitreum liumorem & eum quern albygi- 
Beum nuncubamus repositi.” Vesal. vol, i. p. 558. 
§ Enist, Anat. xvii, 11. 30 
OF THE IRIS. 
ventured to use corona ciliaris. It is a name which conveys 
the idea neither of the shape nor of the substance of the thing 
meant. Ruysch makes great confusion by his use of terms ; 
the corona ciliaris, or ciliary body, he calls the ligamentum 
ciliara; and the lines on the back surface of the iris, he calls 
processus ciliaris musculosus ; or rather, he means by this, the 
straight fibres of the iris.* Duverney, with Ruysch and Wins- 
low, following Fallopius, calls the corona ciliaris also ligamen- 
tum ciliare. But the ciliary ligament is used by others in a 
widely different sense, viz. for the circular root of the ciliary 
body and iris, the anulurn album cellulosum, or the frenula. 
membranosa of Zinn. By Hovius, what I have called halo 
signatus, is called ligamentum Ciliare. In Haller’s fifth figure 
of the eye, this circular root of the ciliary processes is called 
orbiculus ciliaris. Maitre-jean, Haller, and others, call the 
whole body, or corona, the ciliary circle. M. Ferrein, Lan- 
neau de la Choroide, and M. Lieutaud, denominated the 
ciliary processes “ rayon ciliares,” and the root of the corona 
ciliaris and iris, “plexus ciliaris.” 
CHAP. III. 
OF THE IRIS. 
THE'Iris is the coloured circle which surrounds the pupil, 
and which we see through the transparent cornea of the eye. 
It is a membrane hung before the crystalline lens.f It is as 
if perforated in the middle ; and this hole in the middle of 
the iris is the pupil ; and through the pupil only can the rays 
be transmitted to the bottom of the eye. When we hear of the 
dilatation and contraction of the pupil, we have to understand 
the action of the iris, which, by possessing the power of con- 
* Ruysch has this expression : “ Ligamentum ciliare neutiquam esse con- 
siilerandum tanquam musculumad pupillxet humoris cristallini motum desli- 
natum, totumque hoc negocium perfici a i>rocessa ciliari ut et a circulo ituiscu- 
lari posterius in confinio pupillae sito.” Thes. Anat. ii. xv. See also the ex- 
planation of fig. iv. of this Thesaurus, where we have “ Iris enim est facies ex- 
terior, processus lig. ciliaris facies interior.” 
f Winslow and Haller, and most of the old anatomists, call this uvea : by 
which they mean to imply that it is a part of the choroides. See Ophthalma- 
graphia Authore G. Briggs, Cantab. 1676; but most of the modern anatomists 
follow Zinn and Lieutaud in calling it iris; though Lieutaud and others called 
the anterior surface only iris, while they still continue to call this perforated 
membrane choroides or uvea. See Lieut, p. 117. Again, others call the 
posterior surface of the iris uvea, from its likeness to the dark colour df a 
raisin ; and the word iris is borrowed, I suppose, from the varied colours of 
the rainbow. «F THE IRIS. 
31 
trading and relaxing, holds a control over the quantity of 
light transmitted to the bottom of the eye. For, by the exten- 
sion of this membrane, the diameter of the pupil is diminished, 
and, by contraction of the membrane, it is dilated. This motion 
of the iris, and, consequently, the size of the pupil, is con- 
nected with the sensation of the retina; by which means, in 
disease of internal parts of the eye, it is often an index to us 
of the state of the nerve, and of the possibility of giving relief 
by operation. 
The iris, and corona ciliaris, or ciliary processes, are, in 
general, considered as being the two laminae of the choroid 
coat, continued forward and split: the internal lamina of the 
choroid forming the corona ciliaris, and the outer one forming 
the iris. The former I was willing to consider as the anterior 
margin of the choroid coat, because it has no distinction in its 
structure from that coat; but the iris I cannot consider as the 
continued choroid coat; in thc first place, because I have found 
it fall out a perfect circle by maceration; secondly, because it 
has no resemblance in structure to the choroid coat; and, 
chiefly, as by its power of contracting, it shows a widely dif- 
ferent character from any of the other membranes of the eye. 
The outer surface of this circular membrane gives the colour 
to the eye during life ; and from its beautiful and variegated 
colours, it has gained to the whole membrane the name of iris. 
Haller and Zinn, nearly at the same time, explained the cause 
of this coloured iris, which had been, till then, supposed to be 
occasioned by the refraction of the light amongst its stria: and 
libres. 
When this membrane is put in water, and examined with 
the microscope, its anterior surface is seen to be covered with 
minute villi. The splendid colouring of the iris proceeds from 
the villi; but by beginning putrefaction, the splendid reflection 
fades, as the brilliant surface of the choroid of brutes is lost by 
keeping. For this reason, I imagine the colour and brilliancy 
of the iris to depend on the secretion of these villi. But the 
colour of the iris depends, in a great measure, on the black 
paint upon its posterior surface shining through it; and the 
black and hazel-coloured iris is owing to the greater degree oi 
transparency of the iris, which allows the dark uvea to shine 
through it. 
The iris is acknowledged to be the most acutely sensible 
part in the body. We have, then, to expect in its composition, 
muscular fibres, and to account for its acute irritability and sym- 
pathy, by a profusion of nerves: again, as the power of the mus- 
cular fibre, and the sensibility of the nerve, are both, in some 
measure, indebted to the circulation of the blood, we may ex- 32 
OF THE IRIS. 
pect to find also a profusion of vessels in the iris. In all these 
respects we shall find the iris to be an object of admiration. 
OF TIIE MUSCULAR FIBRES OF THE IRTS. 
It is evident, from a note under the head corona ciliaris, 
that Ruysch had observed two sets of muscular fibres in the 
iris ; for, under the name of ciliary ligament, he describes a 
set of radiated fibres which go from the ciliary processes to- 
wards the circular margin of the pupil: he observed also, the 
circular or orbicular fibres which run round the margin of the 
pupil. Winslow says, that between the two laminte of the 
uvea (viz. iris) we find two thin planes of fibres, which appear 
to be fleshy : the fibres of one plane orbicular, and lying round 
the circumference of the pupil, and those of the other being- 
radiated ; one extremity of it being fixed to the orbicular plane, 
the other to the great edge of the uvea. Zinn describes, with 
much minuteness, radiated fibres, (on the anterior surface ol 
the iris,) but does not consider these as muscular fibres ; and 
he confesses, that he could not observe the orbicular muscles 
which Maitre-jean and Ruysch had painted. Even in owls 
and other creatures having a strong iris, he could not discover 
an orbicular muscle ; nor were Haller and Morgagni more 
successful in this investigation.* Wrisberg also affirms, that 
no muscular fibres could be seen in the iris of the ox. Dr. 
Monro, on the other hand, adheres to the opinion of the mus- 
cularity of the iris ; he describes minutely both the radiated 
and sphincter fibres. Wrisberg and others have thought they 
found sufficient proof against the muscularity of the iris, in the 
fact of its not contracting when the light falls upon its surface. 
To this Dr. Monro answers, that the colour or paint upon the 
iris must, like a cuticle, prevent the light from irritating the 
iris. I cannot think that this circumstance should prevent the 
excitement of the iris. The retina is in a peculiar manner 
susceptible of the impression of light; but we cannot wonder 
that light should not stimulate a muscle to contraction, when 
we have every proof that it has no effect on the most delicate 
expanded nerve of the other senses. 
That the iris is to be affected only through the sensation ol 
the retina, or perhaps rather the effect communicated to the 
sensorium, we have sufficient proof. I have, in couching, re- 
peatedly rubbed the side of the needle against the iris without 
exciting any motion in it: I have seen it pricked slightly by 
* See Zinn, p. 89 and 90. Morgagni Epist. Anat. xvii. § 4. Haller and 
Ferrein attribute the motion of the iris to an afflux of humours in its vessel of the iris. 
33 
the needle without its showing any sign of being irritated; nay, 
what was too convincing a proof, I have seen it cut by falling 
before the knife in extracting the cataract. In this last in- 
stance, far from being stimulated to contraction, it hung re- 
laxed.* 
It is evident, then, that no common stimulus, immediately 
applied to the iris, has any sensible effect in exciting it to con- 
traction ; and that it is subject only, in a secondary wray, to the 
degree of intensity of light admitted to the retina. The 
movement of the iris is in general involuntary ; but terror and 
sudden fright affect it. In some animals, particularly in the 
parrot, it is a voluntary muscle.f As an object, upon which 
we look, approaches the eye, the pupil contracts, which is an 
effect of the increasing intensity of the light reflected from the 
object; for, as the object advances, it fills a greater space in 
the sphere of vision, and of course more rays flow from it into 
the eye. 
Nerves of the iris.—The iris is supplied wuth nerves in 
great profusion. They are derived from the long ciliary 
nerves which run forward betwixt the cornea and choroid coat 
towards the common root of the corona ciliaris and the iris. 
They there divide, and are seen to pass in numerous branches 
into the substance of the iris. In the substance of the iris, 
the branches of the nerves, from their extreme minuteness, are 
soon lost amongst its pale fibres. 
Blood-vessels of the iris.—I have had preparations 
which showed so great a degree of vascularity in the iris, that 
I was ready to believe its action to be produced entirely by a 
vascular structure ; but when, on other occasions, my admira- 
tion w as excited by the profusion of nerves, and I was led to 
observe that in the former instances they had been obscured 
by the injection, I could not but allow that the muscular fibres 
might have been obscured as the nerves were. 
There are four arteries sent to the iris : two long ciliary ar- 
teries which take a long course on the outside of the choroid 
coat, and two lesser and anterior arteries which pierce the liga- 
mentum ciliare from without. These arteries approach the 
* This fact destroys the hypothesis of M. Mery, of the Royal Acad, of Sci- 
ences, that the straight fibres of the iris are little cavernous bodies, and that 
the action of the light upon the retina swelled and elongated them so as to 
cause the diminution of the size of the pupil; for by this cut, they must 
have fallen from their erected state, and contracted so as to have dilated 
the pupil. See Acad. Roy. des Sc. 1704, Mem. p. 261. 
-j- When a cat is roused to attention, as by the scratching of a mouse, it di 
lates the pupil, which allows a stronger impression on the bottom of the eye; 
nay, whenever puss struggles violently to get loose, the pupil dilates, which 
may sufficiently account for M. Mery’s cat having her pupil dilated when lie 
plunged her under the water. See Acad. Roy. des Sc. 1704, Men), p. 261. 34 
CHOROID COAT AND IF,IS, 
root of the iris at four opposite points, and branching widely 
form a vascular circle round the rootof the iris, viz. the larger 
circle of the iris. From this circle branches pass off, which 
run with a serpentine course, converging to the edge of the 
iris: here they again throw out inosculating branches, which 
form a circle surrounding the pupil, but at some little distance 
from the edge of the iris—this is the lesser circle of the iris. 
From this lesser circle there again proceed minute branches 
towards the edge of the iris.* 
The veins, which intermingle their branches with these ar- 
teries, pass some of them into the vasa vorticosa of the choroid 
coat, and others take a long course betwixt the choroid and 
sclerotic coat, accompanying the ciliary nerves, whilst some 
branches pierce the sclerotic coat at the root of the iris, and 
become superficial upon the fore part of the eye. 
It was at one time believed, on the authority of many excel- 
lent anatomists, that the vessels of the iris were colourless, and 
did not circulate red blood: after what has been said, it is 
scarcely necessary to mention the fallacy of this opinion.f I 
have seen the iris cut and bleeding, though not profusely as I 
expected ; the small quantity of blood soon coagulated into a 
dark speck, while I expected it should have been effused in 
the aqueous humour. 
There is a circumstance in the operation of extracting the 
cataract which I have seen little attended to, and yet it is suf- 
ficiently evident. When the cornea has been cut, operators, 
disappointed in not finding the cataract protruded, keep the 
eye staring in the light, and press the ball of the eye ; but 
while the eye is thus exposed to the excitement of the light, 
the pupil is contracted, and the lens propelled by the action 
of the muscles ; and, still more, by the pressure made on the 
eyeball, is in danger of pressing through and tearing the iris. 
The best operators have been in the custom of shutting the 
eyelids the instant the incision is made in the cornea ; by 
this means, the eye is for a time supported in some degree 
during the violent spasm of the recti muscles, and the iris 
being allowed to dilate, the lens is protruded into the anterior 
chamber of the aqueous humour through the pupil, and is 
ready to slip from under the cut cornea, when the eye-lids are 
again opened. By this means, if the incision of the cornea 
is of the proper extent, the lens is not extracted, but \s protruded, 
by the action of the muscles of the eye. 
* See Ruysch. Epist. Anat. Frob. xiii. p. 31. 
| Dr. Monro, in treating of this subject, mentions his having seen a net- 
work of vessels covered with paint darker than that of the iris, and extended 
from the iris upo,n the surface of the lens; and, in another instance, a net- 
work of filaments passing quite across the pupil. See his Dissertations, ,p. 1Q8. CHOROID COAT AND IRIS. 
35 
It is very necessary for us to remember, that all the parts of 
the eye, in themselves extremely delicate, are kept in their 
relative places, not by adhesions, but by the complete sup- 
port they derive from the globular form of the eye, and by 
the strength of the outer coat or sclerotic and cornea. To this, 
it is particularly necessary to attend, in the operation of the 
extraction of the cataract; for, as soon as the aqueous humour 
is evacuated, the uniform resistance of the coats of the eye 
is destroyed, and the muscles surrounding the eye-ball force 
all the humours towards the incision. It is this circumstance 
which brings the iris into great danger of being cut when the 
knife is too narrow to make the incision at once, by pushing 
it through the cornea with an uninterrupted motion of the 
lingers. For, when the knife is not broad enough to cut itself 
out by moving it uniformly along, the aqueous humour escapes 
in the endeavour to cut downwards, and the iris is protruded 
so as to fall under the edge of the knife ; nay, with a good 
knife, and of a shape to cut itself out, and at the same time 
adapted to make a cut in the cornea sufficient to allow the 
escape of the lens, I have seen, in consequence of a hesitating 
manner of introducing the knife, the aqueous humour suffered 
to escape. Now, observe the consequence of this :—The lens 
being pushed outwards by the contraction of the muscles on 
the eye ball, towards that point at which the continuity and 
consequent uniform resistance of the coats were broken, the 
margin of the iris was forced under the edge of the knife and 
cut, as I have here represented. 
Fig. 2. 
The margin of iris fallen before the edge of the 
knife and cut. 
A very particular effect of this cut upon the margin of the 
iris is to be observed.—When the incision has been happily 
done, the lens is protruded uniformly through the pupil; but 
when the iris was cut, as now explained, the edge of the lens 
opposite to the'part of the iris which was cut, was forced for- 
ward ; the lens was turned side-ways, rvithout being entirely 
displaced; and a great part of the vitreous humour was allow- 
ed to escape.* 
* See further, Operative Surgery, by C. Bell 36 
OF THE RETINA. 
CHAP. IV. 
OF THE RETINA, AND DIGRESSION CONCERNING THE SEAT 
OF VISION. 
The term retina has, in a modern publication, been objected 
to, as improperly applied to the inner coat of the eye. Such 
a term, it has been said, may well be applied to the nerve 
expanded on the lamina spiralis of the cochlea, because it is 
there formed into an intricate plexus by innumerable joinings 
and separations of its component parts; but used for the ex- 
panded nerve of the eye, the term retina is thought improper.* 
We must look for the resemblance, however, which justifies 
this term, not in the medullary matter of the nerve, but in its 
vessels. “ Hanc figuram egregie repraesentat dicta tunica 
retina cum arteriolae ceracea materia sunt repletae.”j 
The retina is the expansion of the optic nerve ; the imme- 
diate seat of sensation, and the most internal of those mem- 
branes which are called the coats of the eye. It has been 
already observed, that there is a distinction betwixt a nerve in 
its course from the brain to the organ of sense, and where it is 
actually expanded and adapted to the reception of the external 
impression. Before the optic nerve has perforated the sclerotic 
coat of the eye, it is surrounded with a firm sheath ; and its 
substance is evidently composed of bundles of fibres, though 
not so coarse, yet like those of the nerves in the other parts of 
the body. The opacity of the nerve makes it have little the 
appearance of vascularity, but when the body of the nerve is 
made transparent, it becomes like a red cord ; so necessary is it 
that the medullary substance of the nerve be supplied with blood. 
The stronger sheath which surrounds the body of the optic 
nerve is loose, and may be separated into lamellae. There is 
a more delicate membrane which immediately adheres to the 
surface of the nerve; and its substance is formed into the mi- 
nute fasciculi which give it the fibrous appearance by a still 
firmer intertexture of membrane. This interwoven membrane 
proceeds, with the retina, into the eye ; the other sheaths are 
reflected off, and unite with the sclerotic coat. Some little 
way from the back part of the eye, the arteria centralis retinae 
pierces the sheath of the nerve, plunges into the centre, and 
passes into the eye along with it. If the optic nerve be cut 
near to the eye, the open mouth of this small artery may be 
seen ; but if we make our section some way removed from the 
* l)r. Monro’s 4to. Treatises. 
t Ruysch. Epist. Anat. xiii. p. 14. Quamobrem servave adhuc retinae, ap- 
pellationem si non ex fibrarum ut certe ex vasorum implicatione, &c. Mor- 
gagni Epist. Anat.xvii. §43. Of THE RETINA. 
37 
back of the eye, it will, of course, not be seen. The space left 
by the artery contracting in the centre of the nerve when thus 
cut, (or perhaps it was the open mouth of the artery itself,) 
was observed by the ancients, and by them called the porus 
opticus; they were ignorant of this central artery of the retina.* 
Where the optic nerve is about to enter into the ball, of the 
eye, it is much diminished in diameter; it is contracted and 
condensed, and, at the same time, lays aside the strong coats. 
The proper nerve then perforates a cribriform lamina in the 
sclerotic coat. Within the eye, the filaments seen in the nerve 
are no longer distinguishable; but from the extremity of the 
nerve the fine web of the retina is produced. 
The lamina cribrosa, and the delicate fasciculi of the 
optic nerve, are shown in this manner: after making a section 
of the eye, wash away the retina from the extremity of the 
optic nerve, and also the choroid coat; then press the optic 
nerve betwixt the finger and thumb, when the pulp of the 
nerve will be seen to protrude through the foramina in the 
sclerotic coat like white points. It is observed by Zinn, that, 
in doing this, there is a central foramen which remains unfilled 
up by the compression of the nerve. This is the hole perfo- 
rated by the arteria centralis retinas.f Where the threads of 
nerves are accumulated after passing these foramina, and before 
they are finally expanded into the retina, they necessarily form 
a small cone or papilla. This conical form of the extremity 
of the optic nerve is much more evident in some animals than 
in others; but in a section of the human optic nerve we may 
also observe it4 
The retina is a membrane of the most delicate texture of 
any in the animal body: it is transparent in the recent state, 
and so soft, that it will tear with its own weight. In spirits 
and weak acids, it becomes opaque and firmer. It lies expand- 
ed over the vitreous humour, and contiguous, but not adhering 
to the choroid coat, or its pigment. The retina does not con- 
sist merely of the expanded nervous matter, but has in its com- 
position a very fine membrane, and many minute vessels. 
When the retina is macerated for a considerable time, the pulp 
of the nerve can be washed away, and there remains only the 
reticulated and delicate membrane which supports the vessels 
* Porum opticum Herophilus et omnis ab ea antiquitas dixit,foramen nempe 
quod in dissecto nervo de vacua arteria superest. Hall. Alter. Ocul. Hist. p. 
42. De Vasis Nervi Optici vide Ruysch. Epist. Anat. xiii. tab. xvi. Albinus 
Acad. Anat. lib. vii. c. vii. 
j- Zinn de oculo humano p. 106. Com. Repp Soc. Scient. Gotting. loc. cit, 
About 30 foramina have been observed in the lamina cribrosa. See Haller 
Ease, de Arter. Oculi, p. 42. 
+ Zinn. “ At the place which answers to the insertion of the optic nerve, 
we observe a small depression, in which lies a sort of medullary button ter- 
minating in a point.” Winslow, p. 78. 38 
OI' THE RETINA. 
that nourish it. liut though the pulp of the nerve may be dis-* 
solved, it cannot, by dissection, be freed from the membrane 
which supports it.^ 
I have a preparation which more resembles some of Ruysch’s 
plates than any I have seen. In this preparation, the nerve 
being washed away, we may see distinctly the whole course of 
the arteria centralis retinse. Of this preparation I have given 
an engraving, to show how plentifully this organ is supplied 
with red blood ; from which circumstance we may learu the 
strict dependence of its function on the circulation, and deduce 
the derangement of the powers of vision, as a natural conse- 
quence of the disordered action of these vessels. 
The soft medullary matter of the retina is towards the sur- 
face of the choroid coat, and forms there a lamina, which ap- 
pears to me to be the surface of the nerve upon which the rays 
of light impinged The vessels of the retina run upon the sur- 
face contiguous to the vitreous humour4 The arteria centra- 
lis retinse is derived from the ophthalmic artery. It pierces the 
optic nerve, as we have already observed, and enters the eye 
through the porus opticus, to supply the retina. But the arte- 
ries of the retina do not always enter into the eye in one 
trunk; on the contrary, sometimes two or three branches 
pierce the lamina cribrosa,§ and afterwards, two, three, or four 
principal branches, spread out on the circumference of the re- 
tina; from these, the ramifications are so numerous, that 
Ruysch describes them as constituting the membrane.|j Cor- 
* Posse vere Medullarem retinxlaminam removeri ut vasculosum rete mem- 
branx figuram retiueat, alteramque ab altera integrant detrain ultra hommum 
artem positum esse videtur nec ulli unquam contigisse legere tne memini, etsi, 
deleta raacerendo medulla, rete vasculosum laminam peculiarem refer re videa- 
tur. Ex quibus omnibus elicio retinam esse tunicam simplicem, ex celiulosa 
conflatam : que vascula et substantiam medullarem sustinet etsi duas diversas 
ostendat facies alteram vasculosam interiorem, alteram medullarem exterio- 
rem.” Zinn, p. 112. 
f “ C’est sur-tout dans les poissons qu’il est facile de distinguer et meme de 
separer ces deux lames ” Cuvier, tom. ii. p. 419. 
The opacity of the outer surface of the retina prevents the vascularity from 
being apparent. Albinus, after a very minute injection, observed that when 
he lifted up the choroid coat, the vascularity of the retina was not seen: 
“ Autem de ea aliquid acuto scalpello subtiliter levissimeque deradens, mox 
conspicia vasa implcta multa qux sub medulla cujus nimirum portionem de- 
raseram latuerant.” Albin. An. Acad lib. iii. cap. xiv. 
f Ur Monro has these words, expressive of an opposite opinion: “ The 
whole appears to be composed of an uniform pulpy matter, on the outer side of 
which chiefly vessels are dispersed, supported, I suppose, by a membrane the 
same or analogous to the pia mater.” 4to. Treatises on the eye, ear, &c. 
§ Haller loc. cit. Morgagni. Ep. Anat. xvi. n. 44. nor do they always pierce 
the centre of the nerve exactly. Morgagni. 
|| “ Iteratis perscrutiniis reperio oculis armatis arteriolarum extrema tam 
esse numerosa & tam arete sibi invicem et intricate annexa ut peculiarem re- 
presentent membranulam ex arteriolarum extremis constitutam, cui connectc- 
tur dicta medullosa substantia.” Ruysch. Epist. Anat. xiii. p. 15. OF THE RETINA. 
39 
responding with the arteria centralis retinae in the adult, there 
are veins, the minute extremities of which, after forming con- 
nections with the veins of the corona ciliaris, run backwards 
on the inner surface of the retina in three or four distinct 
branches. These uniting into a trunk, perforate the lamina 
cribrosa, and become the socia arteriae centralis. 
Many have been led to believe, that the retina terminates 
forward on the roots of the ciliary processes, as others have 
conceived it to be continued over the forepart of the vitreous 
humour, and over the surface of the lens ;* but the most pre- 
valent opinion is, that it terminates on the margin of the lens. 
That the retina extends over the back of the lens, and re- 
ceives there the impression of light, is very improbable ; but 
that the membrane which supports the retina, is continued over 
the lens, is demonstrable. As I have just said, the retina I con- 
ceive (with Albinus, M. Ferrein, and others) to consist of two 
distinct parts, viz. the medulla of the nerve, and the pellucid 
membrane supporting it; but, however reasonable this conclu- 
sion is, I cannot believe that these portions are to be separated 
by dissection. It is, by most anatomists, believed,that the retina 
passes forward between the vitreous humour and ciliary body, 
and adheres to the margin of the lens. Now, as this adhesion 
is not a gluing together of parts, but a union or intermixture of 
membranous filaments, the interchange and mingling of fibres, 
we may safely say, that the membrane of the retina is con- 
tinued over the lens, and forms part of its capsule. The opacity 
of the retina is diminished at the root of the ciliary processes, 
and disappears altogether at the margin of the lens; and here 
it is not only changed by becoming perfectly transparent and 
allied to the membranes of the humours, but it becomes also 
distinguishable from the opaque retina by a greater toughness 
and strength. The continuity of the retina with the capsule of 
the lens is more apparent, when both membranes have become 
opaque by being immersed in spirits or vinegar, but more par- 
ticularly when that opacity is produced by disease. In disease, 
I have found the veins of the retina running over the margin 
of the lens, and branching on its posterior convexity. 
Where the retina lies betwixt the vitreous humour and the 
ciliary processes, it is plaited, and descends into the interstices 
of these processes. 
When we take oft' the sclerotic and choroid coats of the eye, 
by dissecting them round the insertion of the optic nerve, and 
* Many anatomists, Winslow, Cassobohm, Ferrein, Lieutaud andHaller, have 
taught that the retina extends over the great convexity of the lens, or that it 
is inserted into it. Galen believed it to extend over the lens. For an impartial 
history of opinions, see Morgagni Epist. Anat. xvii. 47. and Zinn, 114. 40 
OF THE RETINA. 
fold them back, carefully preserving the retina; and when wc 
have taken away the ciliary processes from their adhesion to 
the forepart of the retina, we find the retina to form a sac sur- 
rounding the vitreous humour, and supporting the lens. In 
all this surface, the membrane is smooth and uninterrupted. 
To the margin of the lens all this sac is opaque; because upon 
the outside of the retina, is the opaque pulpy nervous matter, 
but the coats of the lens are transparent, yet continuous with 
the arachnoid portion of the retina. When these parts of the 
eye are thus dissected, they hang altogether by the optic 
nerve; viz. the lens, the vitreous humour, and the expanded 
matter of the nerve being supported by delicate and pellucid 
membranes, constituting part of the retina; and the organ is 
divested only of its outer apparatus; we still retain within this 
the more essential and important parts. 
There is here a natural division; and I am willing to pause 
upon this, knowing well with how much difficulty the student 
gains a knowledge of the minute structure of the eye. All 
within the connections of the retina I shall call the internal 
globe of the eye, as distinguishing it from the outward coats 
of the eye and parts subservient to them. A view of the little 
vascular system of these internal parts, thus classed, will show 
how strictly they are connected together, and how much in- 
sulated from the other parts. 
But this is a subject upon which we cannot venture until we 
have considered the nature and relative situation of the 
humours of the eye. 
DIGRESSION ON THE SEAT OF VISION. 
M. L’Abbe Mariotte discovered the curious fact, that when 
the rays fall upon the centre of the optic nerve, they give no 
sensation. He describes his experiment in this manner:— 
“ Having often observed, in dissections of men as well as of 
brutes, that the optic nerve does never answer just to the mid- 
dle of the bottom of the eye ; that is, to the place where the 
picture of the object we look directly upon is made ; and that, 
in man, it is somewhat higher, and on the side towards the nose; 
to make, therefore, the rays of an object to fall upon the optic 
nerve of my eye, and to find the consequence thereof, I made 
this experiment. I fastened on an obscure wall, about the 
height of my eye, a small round paper, to serve me for a fixed 
point of vision; I fastened such another on the side there- 
of towards my right hand, at the distance of about two feet, 
but somewhat lower than the first, to the end that I might 
strike the optic nerve of my right eye while I kept my left OF THE RETINA. 
41 
shut. Then I placed myself over against the first paper, and 
drew back by little and little, keeping my right eye fixed and 
very steady upon the same, and being- about ten feet distant, 
the second paper totally disappeared.”^ 
This defect in the vision of the one eye is corrected by that 
of the other ; for the insertion of ,the optic nerves being to- 
wards the side next the nose, no part of an image can ever fall 
on the optic nerve of both eyes at once ; the defect of vision, 
therefore; is observed only in very careful experiments. Ex- 
periments were, however, made by M. Picard, Marriotte, and 
Le Cat, to render this effect produced by the image falling on 
the centre of the optic nerve evident, when looking with both 
eyes. Marriotte’s second experiment was this : Place two 
round pieces of paper at the height of your eyes, three feet 
from one another, then place yourself opposite to them at the 
distance of 12 or 13 feet, and hold your thumb before your 
eyes at the distance of about eight inches, so that it may con- 
ceal from the right eye the paper that is to the left hand, and 
from the left eye the paper to the right hand. If now, you 
look at your thumb steadily with both eyes, you will lose sight 
of both the papers.f The novelty of such a discovery was 
likely, as frequently is the case, to carry men’s minds beyond 
the true point. It requires time for such facts to descend to 
their level, in the scale of importance, with other less novel 
observations. Mai'riotte, upbn this fact, formed a new hypothe- 
sis relating to the seat of vision. We have observed, that the 
choroid coat and pigmentum nigrum are deficient, where the 
optic nerve enters the eye, and is about to expand into the 
retina. He fixed upon the most unaccountable supposition, 
that the retina does not receive the impression of the rays, but 
that the choroid coat is the seat of the sense. In support of 
this theory, he soon found other arguments than those arising 
from the deficiency of the choroid coat at the entrance of the 
nerve. He saw that the pupil dilated in the shade, and con- 
tracted in a more intense light; now, says he, as the iris is a 
continuation of the choroid coat, this is a proof of the great 
sensibility of that coat: again, the dark colour of the choroid 
coat he supposed to be well calculated for the action of the 
rays of light, which are not reflected from it or transmitted, 
but absorbed; while, on the other hand, the retina is transpa- 
rent. It vision were performed in the retina, says Marriotte, 
* Vide Phil. Trans. No. 35. Smith’s Optics, Remarks on art. 87. 
f Dr. Smith made the stream of light through the key-hole of a dark chamber 
fall upon this point of the retina, opposite to the termination of the optic nerve, 
but he found it quite insensible even to this degree of light. M. Picquet asserts, 
that very luminous objects make a faint impression on the centre of the optic 
nerve. But Dr. Priestley says, that a candle makes no impression on that part of 
his eye. 42 
ar THE RETINA. 
it seems that it should be found where ever the retina is ; and 
since the retina covers the whole nerve as well as the rest of 
the bottom of the eye, there appears no reason why there 
should be no vision in the place of the optic nerve. M. Pic- 
quet argued in opposition to Marriotte. He observed, in re- 
gard to the fitness of the black colour of the choroides for the 
action of the rays of light, that the choroid is not universally 
black ; that there are many shades of difference in the human 
eye ; and that it is black, blue, green, yellow, or of a metallit; 
shining surface, in a variety of animals. He conceived that 
the defect of vision at the insertion of the nerve is occasioned 
by the blood-vessels of the retina.* He observed, also, that 
the opacity of the retina is such, as necessarily to obstruct the 
transmission of the rays of light to the choroid coat. M. de 
la Hire took part in this controversy. He considered the retina 
as the organ of sight, although a particular point of it is not 
susceptible of immediate impressions from outward objects ; 
for, says he, we must not conceive sensation to be conveyed by 
any other means than by the nerves. But, observing the con- 
stitution of the other organ of the senses, he entertained an 
idea that the retina receives the impression in a secondary way, 
and through the choroides, as an intermediate organ; that, b\r 
the light striking the choroid coat, it is agitated, and commu- 
nicates the motion to the retina; and we find that through all the 
organs of the senses, he continues, the nerves are too delicate to 
be immediately exposed to the naked impressions of external 
bodies. 
Another objection to the opinion, that the retina is the seat of 
sensation, has been lately urged, viz. that the thickness of this 
coat, together with its transparency, allows of no particular sur- 
face for covering the image; and that its transparency would cause 
a partial dispersion, which would produce a confusion in vision. . 
If these opinions require serious refutation, we have it in 
the effects of the diseases of the retina, optic nerve, and brain. 
But the thalami nervorum, the optic nerve, and its expansion 
into the retina, seem scarcely to have ever occurred to these 
speculators, as worthy of notice in this investigation. 
The following appears to me the true account of this matter. 
It is demonstrated that the inner surface of the retina is a web 
* Against this hypothesis, the size of the insensible spot was urged by Mar- 
riotte. Bernouilli calculated that this spot is a circle, the diameter of which 
is a seventh part of the diameter of the eye, and that the centre is 27 parts of 
its diameter from the point opposite to the pupil and a little above the middle. 
| M. Le Cat thought the pia mater was the sentient part of the nerve. It 
was, therefore, a kind of confirmation of his opinion to suppose the choroid to 
be the seat of vision, as he teaches that the choroid coat is a production of the 
pia mater. He conceived that the retina moderated the impression of light 
upon the choroid coat, as the cuticle dulls the impression on the papillae of the 
tongue. OF THE RETINA. 
43 
of membrane conveying vessels, and that the outer surface of 
the retina consists of the pulpy-like nervous matter. This lat- 
ter, then, is the organized surface adapted to receive the im- 
pression of the rays of light. At the point where the optic 
nerve comes through the coats of the eye, there is no posterior 
surface peculiarly adapted to receive the impression of light; 
and as well might we expect the optic nerve to be sensible to 
the impression of light in any point of its extent from the brain 
to the eye, as at this ; for here the inner surface of the retina 
only is formed; there is no posterior surface upon which the 
rays can impinge. The doubts regarding the cause of this spot 
giving no sensation, have arisen from the idea, that the inter- 
nal surface of the retina, or its substance, felt the impression 
of the rays of light. 
At the same time, it is evident, that the choroid coat, and 
its secretion is in a most remarkable manner subservient to the 
retina, as the instrument of vision ; for, when the secretion 
is black it absorbs the rays; and animals which have such a 
pigmentum nigrum, see best during the full day: again, when 
the surface is of a shining nature, it repels the rays, and this 
contributes to strengthen the sensation ; and such animals are 
fitted for seeing in obscure light: nay, further, if the surface 
of the choroid be coloured, the animal will see objects of that 
colour the best, because the colour of the choroid depends 
upon its reflecting more of the coloured ray, than of the others 
of which light is composed. 
But as animals see which have no paint on the choroid, neither 
such as will absorb, nor such as will str ongly reflect the rays, 
and which have merely the surface of the choroid with its 
coloured blood-vessels in contact with the retina ; so, it is evi- 
dent, that it is not the deficiency of the choroid coat, nor the 
want of the black paint at the entrance of the optic nerve, which 
prevents the sensation, but really, that there is here no surface 
formed and organized to receive the impression of the light; 
the internal surface not being the sensible surface of the retina. 
FURTHER OBSERVATIONS ON THE RETINA. 
It has already been observed, that vision is the 'combined 
operation of the external organ, nerve, and brain; conse- 
quently, the destruction of the function may be produced by 
disease of the retina, of the optic nerve, or of the brain. 
Any partial injury, pressure, electricity, or galvanism, influ- 
encing the retina, will cause the sensation of light or fire be- 
fore the eye.* Because here, or in its corresponding part of 
* Light from pressure on the eye. See Cartesius, cap. ix. lib. de Meteor, 
and the opthalmo-graphia of Briggs, cornea. 44 
OF THE RETINA. 
the brain, is the organ of vision : and no idea but of light is 
this organ capable of exciting in the mind. Disease in the 
retina, nerve, or-corresponding part of the brain, causing total 
blindness, while the cornea and humours of the eye remain 
pellucid, is called amaurosis. It is, in general, to be con- 
sidered as a paralytic affection. Amaurosis* has been found 
to follow strokes on the head ; concussion and compression of 
the brain; blood effused within the skull; or tumours pressing 
on the nerve or brain.f An amaurosis spasmodica has been 
enumerated by authors. This kind of blindness has been 
supposed to arise in consequence of the stricture of the optic 
nerve by the origins of the recti muscles ; as far as I have ob- 
served, no action of these muscles can affect the optic nerve 
before it perforates the coats of the eye. If it were to be at- 
tributed to the operation of these muscles, I should rather sup- 
pose it to be occasioned by their spasmodic action on the ball 
of the eye, by which the function of the retina may be dis- 
ordered ; but I think it is more probable that the same irrita- 
tion which is acting on the motatory nerves of the eye, does, 
in this instance, affect also the optic nerve and retina. How- 
ever, distention of the coats of the eve, by increased secre- 
tion of the humours, destroys the sensibility of the retina. In 
the hydrophthalmia there is in the beginning a short-sighted- 
ness, so that objects are seen only when near the eye. Thus 
far we might account for the defect of vision by the alteration 
of the focus of the cornea and humours ; but by and bye, as 
the eye enlarges, as it becomes turgid, and the coats more 
distended, the pupil becomes stationary, and the vision is lost 
before the aqueous humour has become turbid.:j: ' 
The connection and sympathy betwixt the retina and the 
viscera of the abdomen is very particular ; I have seen a proof 
* Amaurosis; gutta serexa ; cataracta xigra; which last name is from 
the blackness of the pupil in consequence of the transparency of the lens. 
Ipse vicli bis in puerulis scrophulosis amaurosin, etiam subito ingruen- 
tutn; secto cadavere inveni glandulam strumosam nervis optisis incumbentem.” 
Sauvages Nosol. From many observations, we find that tumours and extravasa- 
tions, which must compress gradually, do yet produce an instantaneous effect. 
In Bonetus,* we have many cases of blindness from abscess in the anterior 
part of the brain ; from fluid on the surface, and in the ventricles; from slea- 
tomatous tumours ; from coagulum of blood, and from a hydatid pressing on 
the union of the optic nerves, and, lastly, from a calculus in the optic nerve. 
Blindness from pressure upon the eye and its displacement and consequent 
elongation of the optic nerve, by an encysted tumour in the orbit, with gradual 
recovery after operations. See Med. Ob. and Inquir. vol. iv. p. 371. 
f To complete such a case, we may further observe, that there is now an 
accession of pain, a tension over the forehead and pericrania, and there is 
sometimes accompanying it a swelling and insensibility of the side of the face. 
So luxation or displacement of the eye, by tumours, causes blindness, by ex- 
tending the optic nerve or compressing the eyeball, and consequently the 
retina. 
* Dc Ocul. Affectibus, Ob. 2. OF THE RETINA. 
45 
of this in the disorder of the stomach having an immediate 
effect on the sensibility of the retina. Allied to this, but greater 
in degree, is the amaurosis which attacks hysterical women 
suddenly, with headach and violent pain. From such sympa- 
thy of parts arise the amaurosis bilosa, verminosa, intermittens, 
arthritica, &c. Such attacks of blindness have been found to 
alternate with convulsions.* 
Commencing cataracts and opacities of the cornea, and of 
the humours in general, give occasion to spots and obscurities 
in the vision ; but we have at present to consider those only 
which depend on the state of the nerve. Errors of vision are 
not easily to be distinguished from those of the imagination 
proceeding from the brain. Error opticus, or hallitcinatio, 
from delirium : one distinction of the former is, that we can 
correct the deception by the assistance of the other senses, 
while, in the latter, the mind is diseased. 
Old people are often troubled with the appearance of dark 
irregular spots flying before the eyes. In fever, also, it is very 
common to see the patient picking the bed-clothes, or catch- 
ing at the empty air. This proceeds from an appearance of 
motes or flies passing before the eyes, and is occasioned by an 
affection of the retina, producing in it a sensation similar to 
that produced by the impression of images; and what is defi- 
cient in the sensation, the imagination supplies ; for, although 
the resemblance betwixt those diseased affections of the retina 
and the idea conveyed to the brain inay be very remote, yet, 
by that slight resemblance, the idea, usually associated with 
the sensation, will be excited in the mind. 
M. de la Hire attributed the fixed spots to drops of extrava- 
sated blood on the retina, and the flying ones, to motes in the 
aqueous humours ;f but we shall show presently, that this ap- 
parent motion of the motes before the eyes may be a decep- 
tion. After turning round upon the heel for some time, objects 
apparently continue in motion. Dr. Porterfield supposed this 
to proceed from a mistake with respect to the eye, which, 
though it be at rest, we conceive to move the contrary way to 
* The following is an ingenious account of the manner in which this may 
be produced, though to me it is not satisfactory:—“ Non infrequens caecitas 
post convulsiones graves et frequentes, sed a nemine quod sciam recte de- 
scripta causa ; hanc non ab humoris affluxu deduco, ut voluerunt, sed quia in 
magnis illis per paroxysmas convulsionum partium omnium, et oculorum simul 
contorsionibus in quibus siepe quoque convulsi, admodumque exerti et inflexi 
apparent, attracto sic nimium et tenso nervo optico, illis adnato illoque simul 
contorto et laeso, spiritusque visorii transitu impedito, oculos visione privari 
contingit, atque inde provenire diligente examine & consideratione inveni- 
mus.” Flaterus, Frax. lib. i. c. 7. 
f “ Guttula crtiroris retinas insidens et nigricans, omnem lucem intercipiet 
unde phantasma obscurum vel nigrum ; verum si dilutus cruor radios rubros 
transmittat tunc maculam rubram videbit scger ut omnia trans vitrum inspecta 
rubra sunt.” Sauvage, vol iv. p. 287. 46 
OF THE RETINA. 
that in which it moved before; from which mistake, with 
respect to the motion of the eye, the objects at rest will appear 
to move the same way the objects are imagined to move, and, 
consequently, will seem to continue their motion for some time 
after the eye is at rest. How superior is simple experiment to 
the most ingenious speculation! Dr. Porterfield is presuming 
in all this, that the eye is at rest when the body is stationary, 
after turning round rapidly on one foot. But the fact is, that 
the eyes continue in motion after the body is at rest, but owing 
to a disorder in the system of sensation we are not sensible of 
it. Dr. Wells, in making an experiment, in which it was ne- 
cessary to look upon a luminous body, was seized with giddi- 
ness, apd he found, that the spot on the retina, affected by the 
great excitement of the luminous body, did not remain station- 
ary, but, when made apparent by looking upon the wall of any 
plane, was moved in a manner altogether different from what 
he conceived to be the direction of his eyes. In making the 
experiment after looking some time at a candle, and then turn- 
ing himself round till he became giddy, he afterwards directed 
his eyes to the middle of a sheet of paper, he saw the dark 
spot (caused by the former brilliancy of the candle on the re- 
tina) take a course over the paper, although he conceived that 
the position of his eyes remained stationary. He then directed 
a person to repeat this experiment, and then bade him look 
stedfastly to him, and keep his eyes fixed; but instead of 
keeping stationary, his eyes were seen to move in their socket; 
though, of this the person himself was quite insensible. 
From these experiments, we may conclude, that spots which 
seem to move before the eyes are not, on that account, solely 
to be attributed to opacity of the humours or cornea, since the 
appearance of motion may be given to those motes, though 
occasioned by an affection of the nerve ; especially, if the un- 
usual sensation be attended with giddiness. Giddiness, how- 
ever, is not necessary to such sensation ; when my eyes are fa- 
tigued, and, sitting in my room, I look towards the window, I 
see before me small lucid circles, which seem to descend in 
quick succession ; upon attending more particularly to my 
eyes, I find them in perpetual motion; my eye is turned gra- 
dually downward, which gives to the spectrum the appearance 
of descending; but it regains its former elevation with a quick 
and imperceptible motion. During the slow inclination of the 
eye downward, the motes or little rings seem to descend; but 
in lifting the eye again, the motion is so quick, that they are 
not perceived.* 
* The following quotation refers to this sensation :—“ .Eger in magna luce 
constitutus, ut plurimum presbyta, vel oculis nitidissimis gaudens continuo 
prx oculos observari sibi putat puncta lucida, qux non hue ct illuc volitant, OF THE RETINA. 
47 
There is a kind of umbrae seen before the eyes which are 
occasioned by the vessels of the retina. Of this kind is the 
suffusio reticularis of Sauvages, in which the person sees um- 
brageous ramifications which strike across the sphere of vision, 
and are synchronous with the pulse, showing its dependence 
on the full and throbbing pulsation of the head. There are 
also corruscations seen before the eyes, in consequence of a 
blow upon the eyeball, and accompanying violent headach, 
vertigo, phrenitis, epilepsy, &c. Whatever forces the blood 
with great violence to the head, as coughing, vomiting, sneez- 
ing, will cause, for the instant, such corruscations, by means 
of the disturbed circulation through the retina. 
We are particularly called upon to attend to the connection 
betwixt the iris and the retina. In amaurosis, the sensibility of 
the retina being entirely lost, the pupil is consequently immove- 
able and dilated.* But we must recollect, that if one eye be 
sound, the pupil of the diseased eye follows, in some degree, 
the movement of the iris of the sound eye. If one eye be shut, 
the pupil of the other eye will dilate ; if the hand be put over 
the eyelids of the shut eye, the pupil will still further dilate.f 
We find several instances of vision indistinct during full day- 
light, and perfect in the crepusculum. This we have explained 
by the dilatation of the pupil allowing the rays of light to pass 
the partial opacity of the lens; it, of course, has no connection 
with the disease of the retina. 
There are also instances of vision being more than naturally 
obscure in the twilight, which is owing to a degree of insensi- 
nec a commoto capite agitantur, ut putat la Hire et ejas in hoc exscriptor 
Boerhaave ; sed constanter si oculos immobilis remaneat, deorsum lentissime 
delabi videntur; adeoque veluti pluvia aurea prae oculos eaque densa cerni- 
tur; quae verticaliter semper descendit in quacunque capitis positura, sive 
erecta, sive lateraliter inclinata; hoc in me ipso expertus per annos, observavi 
in aliis, potissimum illos qui studio nocturno indulserant, etin aegrotante, qui 
de eo symptomate ad melancholiam fere per multos unnos solicitus erat?.” 
Sauvage. This appearance has been attempted to be explained upon the sup- 
position of a very sensible state of the retina, which perceives the gutulx ex- 
uding from the pores of the cornea, and which, falling over its surface, gives 
the appearance of their descending. But it is only felt when the retina is ex- 
hausted or disturbed by pressure on the eyeball. See Sauvages Suftusio 
Scintillans & Suff. Danaes. 
* There are, however, cases of Amaurosis a myosi, in which there is a con- 
tracted and immoveable pupil, and children are born with an insensibility of 
the organ in whiijh the pupil is not greatly dilated. I would be willing to at- 
tribute this peculiarity of the pupil and apparent amaurosis in newly born 
children to the remains of the membrana pupillaris. 
-j- The sympathy of the iris with the retina I do not conceive to be imme- 
diate, but through the intervention of the brain; and the degree of dilatation 
of the pupil, I should hold to depend on the strength of the common sensation 
of both eyes. By this only can we account for the sensibility of the retina of 
one eye affecting the iris of the other, or the disturbance of the brain, in co- 
matose diseases, destroying the sympathetic connection betwixt the retina and 
pupil. 48 
<5F THE RETINA. 
bility.* The night blindness, however, is not to be entirely at- 
tributed to a degree of continued insensibility in the nerve. 
The attacks are irregular, and allied to the intermitting amau- 
rosis. It has been epidemic, and the following cases seem to 
ally it with the paralytic affections.f 
A man, about 30 years old, had, in the spring, a tertian fever, 
for which he took too small a quantity of bark, so that the re- 
turns of it were weakened, without being entirely removed; he 
therefore went into the cold bath, and after bathing twice, he 
felt no more of his fever. Three days after his last fit, being 
then employed on board of a ship in the river, he observed, at 
sun-setting, that all objects began to look blue, which blueness 
gradually thickened into a cloud, and not long after he became 
so blind as hardly to perceive the light of a candle. The next 
morning, about sun-rise, his sight was restored as perfectly as 
ever. When the next night came on, he lost his sight again in 
the same manner ; and this continued for twelve days and 
nights. He then came ashore, where the disorder of his eyes 
gradually abated, and in three days was entirely gone. A 
month after, he went on board of another ship, and after three 
days stay in it the night blindness returned as before,and lasted 
all the time of his remaining in the ship, which was nine nights. 
He then left the ship, and his blindness did not return while he 
was upon land. Some little time afterwards, he went into ano- 
ther ship, in which he continued ten days, during which time 
the blindness returned only two nights, and never afterwards. 
In the August following, he complained of loss of appetite, 
weakness, shortness of breath, and a cough ; he fell away ver\ 
fast, hadfrequent shiverings,pains in his loins, dysury, and vo- 
mitings ; all which complaints increased upon him till the mid- 
dle of November, when he died. He had formerly been em- 
ployed in lead-works, and had twice lost the use of his hands, 
as is usual among the workers in this metal. Medical Trans- 
actions, published by the College of Physicians in London, 
vol. i. p. 60. 
Pye,* servant to a miller, at the 6th mill on the Limehouse 
wall, about 40 years of age, came to me, October 2d, 1754, lor 
advice and assistance. He told me, that about two months 
ago, while he was employed in mending some sacks, near the 
setting of the sun, he was suddenly deprived of the use of his 
* Est immanis differentia inter splendorem et activitatem luminis candela 
etlunrc : luminis Solaris vis est ad vim luminis candela: 16 pedis distantis, obser- 
vante 1). Bonguer ut 11664 ad 1; et ad lumen lunx in pleni lunio, ut 674,000 
ad 1 demonstrante D. Euler Mem. de l’Acad. de Berlin, an. 1750, pag. 299, 
non mirum itaque si vis toties major sufficeret ad succutiendam retinam quarr 
tanto minor non afficiebat. Saavages Amblyopia Crepusculans. 
f By Dr. Heberdeu. 
4 Case by Dr. Samuel Pye or THE RETINA. 
49 
limbs and of his sight At the time he was attacked with this 
extraordinary disease, he was not only free from any pain in his 
head or limbs, but, on the contrary, had a sensation of ease 
and pleasure; he was, as he expressed himself, as if in a pleas- 
ing dose; but perfectly sensible., He was immediately carried 
to bed, and watched till midnight; at which time he desired 
those who attended him, to leave him, because he was neither 
sick nor in pain. He continued the whole night totally blind, 
and without a wink of sleep. 
When the day-light of the next morning appeared, his 
sight returned to him gradually as the light of the sun in- 
creased, till it became as perfect as ever; when he rose from 
bed, his limbs were restored to their usual strength and use- 
fulness, and himself in perfect health. 
But on the evening of the same day, about the setting of the 
sun, he began to see but obscurely, and his sight gradually 
departed from him, and he became as blind as on the pre- 
ceding night, though his limbs continued as well as in perfect 
health ; nor had he, from the first night, any complaint from 
that quarter. 
The next day, with the rising sun, his sight returned; and 
this has been the almost constant course of his disease for two 
months past. From the second night, the symptoms preceding 
the darkness were, a slight pain over the eyes, and a noise in his 
head, which he compared to a squashing of water in his ears. 
After near two months continuance of the disease, on Sep- 
tember the 29th, the patient was able to see all night; on the 
30th September, October 1 and 2, he was again blind all night; 
on the 3d, he was able to see ; on the 4th, he was blind till 12 ; 
on the 5th, was blind. From this he had no return of his com- 
plaint till June, 1755; from which till the 3d of October, when 
I again saw him, he had three or four attacks ; from the 3d 
till the 10th, he had an attack every evening.—He had at this 
time a purging. I ordered him an electuary of bark and nut- 
meg, which succeeded in removing the blindness ; but the' 
diarrhoea continued wasting him. On the 20th, delirium came 
on; on the 21st, he became deaf; he died on the 25th, after 
having suffered from fever, pain in his bowels, and continued 
diarrhoea; but the defect in his eyes never returned after the 
10th. This man had clear, bright eyes ; when his sight failed 
him the pupils were enlarged about one-third in diameter. 
Medical Facts and Enquiries, vol. i. p. 111. I could give 
other cases from my note-book, but these are sufficient. 
Boerhaave gives us an example of imperfect vision, from a 
discordance betwixt the contraction of the iris and the excite- 50 
OF THE RETINA. 
ment of the retina; so that the pupil did not dilate in the pro- 
portion to the decay of light.* 
When inflammation extends within the eye, or when the 
retina is excited by sympathy with the ophthalmia of the outer 
membranes, it may happen that the patient is totally blind dur- 
ing the day, and yet sees on the approach of evening; be- 
cause, from the sensibility of the retina, the pupil is absolutely 
shut, but as the light is diminished the pupil is gradually re- 
laxed, and the obscure light admitted ; and this obscure light, 
from the irritable state of the retina, gives a vivid sensation 
incomprehensible to the bye-standers. Our judgments of the 
strength of sensations are comparative merely; when we have 
been accustomed to strong impressions, lesser ones are disre- 
garded. The greater light destroys the capacity of the retina 
for receiving slighter and more delicate impressions; while, on 
the other hand, the absence of light reserves to us the power of 
seeing objects the most faintly illuminated. We are every day 
becoming more acquainted with the invisible properties of 
light; and we have frequent experience of darkness being 
relative, and that what we should call total darkness is very 
often but a fainter light. One man will see distinctly, when 
another is quite deprived of the power of discerning objects. A 
man in prison seems to have the light gradually admitted to 
him; and many animals are in quick pursuit of their prey, while 
we are groping our way with the assistance of our other senses. 
Animals which seek their prey in a light which is darkness 
to us, have, most probably, a greater degree of sensibility of 
the retina. But they have also a more conspicuous apparatus 
in the largeness of their eyes, and the dilatability of their pu- 
pii, while the sensibility which this provision gives, is often 
guarded from the light of day by the membrana nictitans, and 
by an iris capable of great contraction. Their iris possesses 
also a great power of contraction in narrowing the pupil during 
the day, as it is capable of dilating during the night, to the 
whole extent of the cornea. In the human eye, also, the strict 
sympathy between the iris and retina is a guard to the latter. 
But it has often happened that, in using optical instruments, 
the retina has been hurt by the intensity of the light from the 
concentrated rays: a lesser degree of this effect we have given 
us in the following instance :f 
“ Being occupied in making an exact meridian, in order to 
observe the transit of Venus, I rashly directed to the sun, by 
* In old people there is an obscurity of vision, from a diminished sensibility 
of the retina ; and the iris does not take a quick succession of contraction and 
dilatation with the change of light. OF THE RETINA. 
51 
ifiy right eye, the cross hairs of a small telescope. I had often 
done the like in my younger days with impunity; but I suffered 
by it at last, which I mention as a warning to others. I soon 
observed a remarkable dimness in that eye, and for many weeks, 
when I was in the dark or shut my eyes, there appeared before 
the right eye a lucid spot, which trembled much like the image 
of the sun seen by reflection from water. This appearance 
grew fainter, and less frequent by degree, so that now there are 
seldom any remains of it. But some other very sensible ef- 
fects of this hurt still remain :—For, first, the sight of the right 
eye continues to be more dim than that of the left; secondly, 
the nearest limit of distinct vision is more remote in the right 
eye than in the other, although, before the time mentioned, 
they were equal in both these respects, as I had found by many 
trials ; but, thirdly, what I chiefly intend to mention is, that a 
straight line in some circumstances, appears to the right eye to 
have a curvature in it. Thus when I look upon a music book, 
and, shutting my left eye, direct the right to a point of the 
middle line of the five which compose the staff of music, the 
middle line appears dim indeed at the point to which the eye 
is directed, but straight; at the same time the two lines above 
it and the two below it appear to be bent outwards, and to be 
more distinct from each other and from the middle line, than 
at other parts of the staff to which the eye is not directed. 
Fourthly, although I have repeated this experiment times in- 
numerable within these 16 months, I do not find that custom 
and experience takes away this appearance of curvature in 
straight lines. Lastly, this appearance of curvature is percepti- 
ble when I look with the right eye only, but not when I look 
with both eyes ; yet I see better with both eyes together than 
even with the left eye alone.” 
Herschel, in making his observations on the sun, found the 
irritation proceed from the red rays* (being those of the rays 
of light which have the property of producing heat in the 
greatest degree; he found, when he used red glass to inter- 
cept the too vivid impression of light on his eyes, that they 
stopped the light, but produced an insufferable irritation from 
the degree of heat. But when he used green glass it trans- 
mitted more light, and remedied the former inconvenience of 
an irritation arising from heat. He concluded, that in the 
darkening glasses for telescopes, the red light of the sun should 
be entirely intercepted. Boerhaave mentions an instance of 
the retina being injured by the long use of the telescope, and 
* See a curious instance of red colours producing convulsions in an epileptic 
patient. SandifortThes. vol. iii. page 314. 52 
OF THE MEMBRANA PUPILLARIS. 
he himself was hurt by a similar cause. These injuries are 
owing to the intrusion, of light highly concentrated, and over 
which the pupil has no command ; it is a degree of intensity 
which the organ is not prepared to counteract. 
CHAP. V. 
OF THE MEMBRANA PUPILLARIS. 
The membrana pupillaris is an extremely vascular mem- 
brane, which is extended across the pupil of the foetus. It 
was discovered by Haller, Albinus, Wachendorf,* and Dr. 
William Hunter, at the same time or without correspondence 
with each other. 
Haller,f after injecting, with oil of turpentine and cinnabar, 
a foetus of the seventh month, saw through the cornea the ves- 
sels of the iris injected, and some ramifications from them pro- 
duced into the space of the pupil. From conviction that no 
vessels ramified without an involving membrane, he naturally 
concluded, that a membrane was drawn across the pupil of 
the foetus, though in this instance, it was afjout to disappear. 
In several other foetuses of the seventh month he confirmed 
his first observation ; and, cutting off the cornea, he observed 
the membrane impelled forward by the humours behind, like a 
little vesicle. 
Albinus, in his first book of Academical Annotations, thus 
describes the way in which he detected this membrane. In 
the same child in tvhom he had filled the vessels of the crys- 
talline, he also first observed the membrane which closes the 
pupil, and in which the vessels were injected that came from 
the margin of the pupil. Upon looking through the cornea, 
he could see no distinction of parts, but all seemed vascularity. 
He conceived, at first, that these were the vessels of the uvea, 
and that it had quite contracted and had shut the pupil; then 
that they were the vessels of the capsule of the crystalline 
lens; but having cut into the eye, he found it to be this mem- 
brane. Dr. Hunter, speaking of this membrane, and of Albi- 
nus’s claim to the discovery, says, “ In justice to this great 
anatomist, I must declare that I believe this, both because he 
* In Commercio Norico, A. 1740, hebd. 18. as quoted by Haller 
f I)e nova tunica pupillam fcetus claudente. Oper. minor. OF THE MEMBRANA PUPILLARIS. 
53 
asserts it and because I know from the circumstances it was 
hardly possible he could miss taking notice of it in that child.” 
44 I have always observed (he continues) both in the human 
body and in the quadruped, that there is a great resemblance 
to one another in the vessels of the capsula crystallini and of 
the membrana pupillae. In an injected foetus, I always find 
both nearly in the same state: if one be filled only with the 
blood that is drove before the injection, so is the other; if one 
be filled partly with injection, and partly with blood, the bther 
is in the same condition: if one by good fortune be finely and 
minutely filled with injection, the other is so too; if one be 
burst by extravasations, the other is commonly in the same 
state ; and when the foetus is so near its full time that the one 
cannot be injected, neither can the other.”* 
Dr. Hunter, speaking further of the artery of the crys- 
talline capsule, says, 44 that it does not terminate at the great 
circle of that humour. Its small branches pass that circle, 
and run a very little way on the anterior surface of the crys- 
talline humour before the points of the ciliary processes ; then 
they leave the humour and run forwards, supported on a very 
delicate membrane, to lose themselves in the membrana pu- 
pilloe.” He continues: “The membrana pupillae receives 
two different sets of arteries, one larger, from the iris, and 
the other much smaller, but very numerous from the crystal- 
line capsule.” 
Now I think that every expression in these excerpts con- 
firms the opinion I entertain, that these vessels which are seen 
filled with red blood, and which take their course through the 
humours, are subservient merely to the membrana pupillaris. 
The first time I observed the membrana pupillaris was in 
the eye of a child born at the full time. I had injected the 
child very minutely with size and Vermillion, and the iris was 
beautifully red and the pupil quite transparent and black, and 
not obscured by any extravasation of the injection into the 
aqueous humour: upon very narrowly observing the circle of 
the iris, I saw distinctly a small injected vessel pass out from 
the edge of the iris, and crossing the pupil, divide into two 
branches, which ran into the opposite margin of the iris. This 
was the remans of the membrane, but so delicate and so per- 
fectly transparent, that the presence of it was only to be argued 
from the vessel which was seen to cross the pupil. 
Since that time I have often seen it in the early months, 
and particularly strong about the seventh month of the foetus. 
It is then an opaque, and very vascular membrane, and gene- 
* See Medical Commentaries, p. 63. foot ndte. 54 
or THE MEMBRANA PUPILLARIS. 
rally it has spots and streaks of extravasation in it. The vas- 
cular structure of this membrane is very particular, and I can 
assign no other reason for this than that it may be a provision 
for its rapid absorption. It has evidently two sources of ves- 
sels, viz. the vessels of the capsules and those of the iris; but 
whether the arteries qorne by the one source, and the veins 
depart by the other, I cannot as yet determine. In one pre- 
paration I see the vessels with their trunk in the membrana 
pupillaris, and the branches sent over the surface of the iris. 
The larger and flat venous-like vessels of the membrane are 
distributed in a beautiful net-work, in the form of the lozenge 
of a Gothic window. They have a free communication with 
each other. In their whole course the vessels seem nearly 
of the same size, (which also is like the character of a venous 
net-work,) and they terminate apparently in the margin of the 
iris. 
The use of the membrana pupillaris I think sufficiently ap- 
parent, though I do not find that it has hitherto been under- 
stood. Haller makes a comparison betAvixt this membrane, 
which closes up the pupil, and that matter Avhich is accumu- 
lated in the passage of the ear in the foetus. But there is no 
analogy.—As the waters of the amnios might otherwise be in 
contact with the membrane of the drum of the ear, and in- 
jure what necessarily is of a dry and arid nature, this matter 
accumulated in the ear of the foetus defends it. But at the 
time, when the membrana pupillaris exists in its full strength 
and vascularity, no light is admitted into the eye—the foetus 
is lying in its mother’s Avomb. Towards the ninth month, the 
membrane has become transparent, and if not totally absorb- 
ed, it is torn by the first motion of the pupil and altogether 
disappears. It can therefore have no effect in obscuring the 
light, and preventing it from exciting in too great a degree 
the eye of the newly-born child. To explain the effect of 
this membrane then, we have only to consider that it is of 
the nature of the iris to contract its circular fibres during the 
operation of light, so as to close or nearly close the pupil; 
that, on the other hand, the pupil is completely dilated through 
the operation of the radiated fibres of the iris in darkness :— 
To the question, then, why it is not dilated during the foetal 
state ? The answer, I think, is decidedly this:—The iris is 
not loose in the foetal state, it is connected and stretched to the 
middle degree of contraction and dilatation by the membrana 
pupillaris. Were the iris in a full state of contraction, during 
the life of the foetus, it could not receive its full nourishment, 
proper degree of extension, and due powers ; but being pre- 
served stationary and extended, the disposition to contraction, ©F THE HUMOURS OF THE EYE. 
55 
tvhich it must have when the retina is without excitement, is 
counteracted, until it is about to receive, by the birth of the 
child, that degree of excitement which is to keep up the pre- 
ponderance towards the contracted state of the pupil. 
CHAP. VI. 
OF THE HUMOURS OF THE EYE. 
OF THE AQUEOUS HUMOUR. 
The aqueous humour is perfectly limpid. The use which I 
have assigned to the aqueous humour explains its nature and 
the extent of the chamber which contains it, viz. that it dis- 
tends the cornea and allows the free motion of the iris ; it 
consequently fills the space between the lens and cornea. The 
usual description is, that it is lodged in two chambers ; the 
one before the iris, called the anterior chamber of the aqueous 
humour, and the other behind the iris, called the posterior 
chamber of the aqueous humour. 
This posterior chamber, was, at one time, conceived to be 
of great extent,* and authors spoke of depressing the lens into 
the posterior chamber of the aqueous humour.f It is found, 
now, that betwixt the lens and iris there is no space to which 
we ought to give this name of chamber. 
Heister, Morgagni, and M. Petit (medecin) first demon- 
strated the extreme smallness of the posterior chamber, and 
after them Winslow confirmed the fact, that the iris moved al- 
most in contact with the anterior surface of the lens. 
M. Petit gave the clearest proof of the smallness of the pos- 
terior chamber, by freezing all the humours of the eye, and 
dissecting them in their solid state. Without this expedient 
it was impossible to prove the relative size of the two cham- 
bers ; for, whenever the cornea was cut, the aqueous fluid es- 
caped, and the lens pushed forward. When the eye was fro- 
zen, and then dissected, it was found that the ice, which took 
* Viz. by Heister. They were called the first and second chambers by M. 
Brisseau. 
f There certainly appears sufficient room for this in Vesalius and Briggs* 
plates : these plates have misled many. 56 
OF THE HUMOURS OF THE EYE. 
the shape'and dimensions of the anterior chamber, was much 
larger than that found in the posterior chamber indeed the 
latter was formed of a very thin flake of ice. The thin piece 
of ice in the posterior chamber indicated as much fluid only 
betwixt the iris and lens as might allow a free motion to the 
iris. These experiments were instituted in the course of in- 
vestigating the question of the nature of the cataract. 
The conclusion, that the posterior chamber of the aqueous 
humour contained but one-fourth of the whole aqueous hu- 
mour, was admitted with great difficulty and after much con- 
test. It determined the question, whether the cataract was a 
membrane of the opaque lens ; for, as those who maintained 
that it was a membrane, said it could not be the lens, because 
the lens was far distant from the iris, it was necessary for their 
opponents to prove that the lens was close upon the pupil, and 
that the posterior chamber of the aqueous humour was very 
small. ' • 
It is agreed that in the adult, the quantity of the aqueous 
humour amounts to five grains; in the foetus it is red, turbid, 
and weighs about a grain and a half, owing, in part, to the 
comparatively greater thickness of the cornea. 
As it is natural to conceive that the aqueous humour flows 
from a vascular surface, it is the most generally received opi- 
nion, that it is derived from the points of the ciliary processes 
and surface of the iris. Haller, particularly, and after him 
Zinn, have thought that the ciliary processes were the secret- 
ing bodies ; but there is one argument which, in my mind, de- 
termines that these are not the sole secreting parts, viz. that 
while the membrana pupillaris closes up the communication 
betwixt the two chambers, I have observed the anterior one 
to be full of the fluid, which of course must have been suppli- 
ed from another source than the ciliary processes. I suppose, 
therefore, that the villous surface of the iris is the proper se- 
creting surface of the aqueous humour.f Zinn observes, that 
Haller saw the membrana pupillaris distended and bulged for- 
wards by the aqueous humour in the posterior chamber. It is 
scarcely necessary to say, that this must always take place 
when the cornea is first opened in demonstrating that mem- 
brane, whether there be a watery fluid behind it or not. But 
I believe I shall be able to prove, that the secretion of the ci- 
* See Acad. Roy. des Sciences, 1723. Mem. p. 38. 
t The opinion of Nuck is now out of the question. He thought that he 
had discovered particular aqueducts, which conveyed the aqueous humour into 
the anterior part of the eye ; but these are found to be nothing more than the 
short ciliary arteries which pierce the forepart of the sclerotica. M. Merry 
and Bonhomme (see Zinn, p. 143.) observed, in an adult, the pupil closed with 
the membrane, and in this instance there was scarcely any fluid in the anterior 
chamber, whilst the posterior was turgid with fluid. OF THE KT7H0UES OE THE EYE. 
57 
it ary processes can have little power of filling the posterior 
chamber, even from the connection of membranes behind the 
menibrana pupillaris in the fcetus. The aqueous fluid is per- 
petually undergoing the change of secretion and absorption, 
and this is the reason of its quick renewal when it has been 
allowed to escape by puncture of the cornea. The ancients 
were not ignorant of the quick regeneration of this fluid. It 
was proved to the moderns by a charlatan, Josephus Burrhus 
(ventosus homo, qui in carcere Romano periit.) Before the 
physicians of Amsterdam he punctured the cornea of a dog; 
then instilling his liquor under the cornea, he bound up the 
eye; in a few days he took off the bandage, and showed them 
the cornea again distended with the aqueous humour. It was 
soonfound that the instilled fluid was of no kind of consequence. 
Redi and Nuck made many experiments, and it was found that 
the aqueous humour was regenerated in the course of 24 hours. 
When the disputes regarding the cataract ran high, and 
when, to make new distinctions in the disease was taken as a 
mark of practical knowledge and of acuteness, there was a kind 
of cataract attributed to the aqueous humour. When the aque- 
ous humour became turbid, white, and opaque, and obscured 
the pupil, they were absurd enough to call this a cataract. The 
turbid state of the aqueous humour is at once distinguishable, 
from the opaque lens, because it obscures the iris as well as 
the pupil. 
Pus is formed in the chambers of the aqueous humour, in 
consequence of deep inflammation, contusions, &c. and from 
the same cause, sometimes, proceeds a bloody effusion. When 
the pus has lodged in the anterior chamber of the aqueous 
humour, it would appear, upon the authority of Galen, that an 
oculist of his day performed a cure by shaking the patient’s 
head !* It is an operation of oculists to puncture and allow the 
pus to flow out, and some have even syringed out the pus with 
water ;f but this must have been on the principle of Jos. 
Burrhus’s exhibition; for the natural secretion is here the best 
diluent. When we recollect the nature of the parts with which 
the pus lies in contact, we cannot be sanguine in the hope of 
such an operation saving the eye. Sometimes .there remains, 
* Moucliart says, lie lias often seen the oculist Woolliouse repeat this cure 
by shaking his patient’s head over the side of the bed. He attributed the 
cure to the falling of the pus into the posterior chamber, which, he supposes, 
has parts more capable of absorbing it. 
f They were at variance regarding the place at which to puncture’ for this 
discharge : Some did it behind the iris; there we know there is a crowd of 
vessels; the best place is the lower edge of the cornea before uie iris. It- 
seems to have been no uncommon accident, in this operation, to find the lens 
protruded through the pupil. The reason of this has been already explained# 58 
OF THE HUMOURS OF THE EVE. 
after operation on the cornea, or in consequence of ulceration, 
a continued Hoav of the aqueous humour; the consequence is 
a subsiding of the cornea ;# it becomes corrugated, opaque, 
and from the contact of the iris, apt to adhere to the iris. In 
consequence of this suppuration, there sometimes follows an 
absolute obstruction of the pupil, from the coalescing and ad- 
hesion of the edges of the iris.f 
The vitreous humour, as already explained, occupies almost 
entirely the great ball of the eye. It is consequently beyond 
the lens, and keeps it at the requisite distance, to cause the 
rays from objects to concentrate and impinge upon the retina. 
The vitreous humour is considerably denser than the aqueous 
humour4 Its involving membrane is called membrana hyoloi- 
des sive vitrea.§ The peculiar appearance of this humour, its 
glairy-like consistence, is not owing to its density, but to the 
manner in which it is contained in its membranes. From being 
contained in a cellular structure of perfectly pellucid mem- 
branes, it has the adhesion and consistence of the white of an 
egg. This membranous structure of the vitreous humour has 
been demonstrated by acids and by freezing. When frozen, 
it was found to consist of pieces of ice connected by strong 
membranes, which separated with difficulty, and showed their 
torn fragments : and M. Demours lifted the transparent mem- 
branes with the point of a needle. Although the vitreous hu- 
mour appears to be gelatinous, it is not so in reality, and when 
it is taken from the coats of the eye, it retains the shape for a 
time, but gradually subsides by the fluid exuding from the 
membranes, and this is accelerated by puncturing it. 
THE VITREOUS HUMOUR. 
OF THE CRYSTALLINE LENS. 
The crystalline humour is a small body, of the shape of an 
optician’s lens, of great power. It is of perfect transparency, 
and of density much greater than the vitreous humour. Its 
density to that of the vitreous humour is calculated to be as 
1114 to 1016. But the crystalline is not of uniform density, 
for the centre forms a denser nucleus. 
of the crystalline is that of a compressed sphere, 
* Rhytidosis, seu subsidentia & corrugatio cornea;. 
f Viz. Synisesis. There has occurred congenital imperforation of the popih 
t It is, according to Dr. Monro, in the proportion of 1016 to 1000- 
4 Ophthalmographia authore G. Briggs, 16r6. Cantab. OF THE HUMOURS OF THE EYE. 
59 
the anterior surface being more compressed or flatter, though, 
in a degree, convex. According to Petit, the anterior surface 
is the segment of a sphere whose diameter is 7, 8, or even 9 
lines. The posterior surface is a sphere of 4 or 5, or lines 
in diameter. The internal structure of the lens is quite pe- 
culiar, and resembles neither the vitreous nor the aqueous 
humour. By maceration it splits into lamellae, and at the same. 
time bursts up into equal parts, so that there is first a stellated- 
like fissure, and then it separates into pretty regular divisions ; 
and after maceration in acids, the lens can be teased out into 
minute shreds and fibres.* 
From it form, density, and central nucleus, it has great 
power of converging the rays of light; and in an eye properly 
constituted it concentrates them accurately to the surface of 
the retina. For this reason, it is placed before the vitreous 
humour, and socketed in its anterior part. It is contained in a 
capsular membrane, the tunica ciranea, improperly called,! 
which membrane is continued from, or connected with, the 
membranes of the vitreous humour; but this is a subject 
which requii*es a more particular investigation. 
OF THE CAPSULE OF THE LENS AND VITREOUS HUMOUR. 
Marginal Plate 13. 
Fig. 2. 
Fig. 3. 
Fig. 1. 
Tlie Lens. 
Petitian Canal. 
. Vitreous humour. 
In fig. 1. we have the appearance of the Petitian canal blown 
up. It is not found full of any fluid, it is only the laminae of 
* See further of the muscularity of the lens, 
t Qphthalmograbhia, 60 
OF THE HUMOURS OF THE EYE. 
membrane inflated, and it is best demonstrated when the eye 
is slightly putrid by cutting off the cornea, and with it a small 
circular portion of the sclerotica, and taking with these the 
iris also, when the lens presents itself seated firmly in its cap- 
sule on the vitreous humour. Now laying back the ciliary pro- 
cesses, we make a fine puncture with a lancet by the side oi 
the lens, and then blow gently into it with the blow-pipe. 
Every anatomist acknowledges the existence of the Petitian 
canal, and a distinct capsule to the lens is also pretty generally 
allowed. But many deny that the vitreous membrane has two 
plates, without observing that the existence of the Petitian ca- 
nal is a proof of the splitting of the membrana vitrea, on the 
forepart at least. Some believe that the vitreous membrane- 
splits and involves the lens, and forms its capsule ; but the diffi- 
culty, on this supposition, is still to account for the formation 
of the canal which surrounds the lens ; for as the fluids on the 
surface of the lens and within its capsule have not admission to 
the canal, the canal must be distinct; and, indeed, sometimes 
we blow up the circular canal, and sometimes, by a wrong 
puncture, the capsule of the lens itself; but not both at once. 
Seeing, then, that these cavities are distinct, some anatomists 
have admitted that the membrana vitrea is double ; that the 
lens has its proper capsule; and that the lamina of the vitreous 
membrane, coming near the margin of the lens, splits and in- 
volves it in a second coat, (as in fig. 2.) Others have supposed 
that the anterior layer of the vitreous humour does not pass 
over the anterior surface of the proper capsule of the lens, 
but only adheres to the edge of the capsule of the lens, and 
forms the Petitian canal. There are yet others who have 
described the membrana vasculosa of the retina, as forming 
the capsule of the lens. This is one of those pieces of anatomy 
which provokes us to continued research, and mortifies us with 
continual disappointment. If this piece of anatomy, when in- 
vestigated in the eye of an adult, is difficult to be understood, 
it is infinitely more complicated in the eye of the foetus ; and, 
for my own part, I cannot reconcile my experience with any 
former opinion. 
I conceive that it is the membrana vasculosa tunicse retinae, 
or membrana vasculosa Ruyschii, which forms the vascular 
capsule of the lens in the foetus, and also the canal of Petit in 
the adult. The crystalline lens has, in the first place, its pro- 
per capsule, which surrounds it on all sides : again, the trans- 
parent web of membrane that is continued onward from that 
part of the retina which has upon it the pulpy and nervous 
expansion, splits when it approaches the margin of the lens. 
One lamina goes round behind the lens, and the other passes a OF THE CENTRAL ARTERY. 
61 
little before it, forms an adhesion to the capsule of the lens, 
and is then reflected off to the points of the ciliary processes 
and to the membrana pupillaris of the foetus.* Betwixt these 
split laminre cf the continued membrane of the retina, the(canal 
which surrounds the lens is formed. The membrana vitrea 
is simply reflected over the back of the lens, and has no part 
in forming the Petitian canal. Where the retina advances 
forward upon the ciliary processes, it forms an adhesion, be- 
yond which the medullary part is not continued ; but the mem- 
brana vasculosa passing onward, as I have described, embraces 
the lens, and the lamina, which passes behind the lens and be- 
fore the vitreous humour, receives and conveys the artery 
of the capsule ; on the forepart of the lens the anterior lamina 
only touches the capsule of the lens, adheres, and is then re- 
flected off to form the membrana pupillaris. 
In this account I am supported by the most careful investi- 
gation, and by the simplicity of this system of vessels : for it 
will be observed, that it is on the membrana vasculosa alone, 
that the vessels carrying red blood in the fcetus, are supported, 
and that it shows throughout the same character for vascu- 
larity. Again, I think it probable that this membrane which 
passes before the lens, viz. the membrana pupillaris, and that 
which passes behind the lens, forming the vascular capsule of 
the lens, disappear at the same time ; or if this posterior and 
vascular membrane which passes behind the lens is not totally 
absorbed, it becomes thin and more intimately united to the 
membrana vitrea. 
CHAP. VII. 
OF THE DISTRIBUTION OF THE CENTRAL ARTERY AND VEIN 
OF THE RETINA. 
I am the more anxious to give the accurate distribution of 
these vessels, that Walter’s account of them has tended much 
to derange that simple and natural view of this system which 
observation authorizes us to take. 
The arteria centralis retinae arises from the ophthalmic ar~ 
* In the foetus, as far as I have observed, the proper capsule of the lens and 
the membrana pupillaris, lie in contact, but they do not adhere; and while 
the membrana pupillaris is perfectly red with injection, there is none to be 
seen on the forepart of the capsule. There is, indeed, no part of that surface 
which is afterwards to secrete the aqueous humour, which could secrete that 
fluid, betwixt the surface of the lens and membrana pupillaris ; so complete 
is the adhesion of the adventitious and vascular tunic of the lens to the mem- 
brana pupillaris. 62 
OF THE CENTRAL ARTERY. 
tery.5* Sometimes it is derived from the ciliary arteries before 
they enter the coats of the eye, and often there is more than one 
branch entering the optic nerve.f Arising from this source, there 
are many branches which are distributed to the retina, while a 
branch passes onward from the lamina cribrosq through the vi- 
treous humour to the capsule of the lens. This vessel does not 
pass exactly in the centre of the vitreous humour, but to one 
side-of the axis of the eye. When it arrives near the capsule of 
the lens, it divides into three or four branches, which, reaching 
the capsule, spread beautifully on the back part of it4 
The branches of the arteria centralis retinae, which are dis- 
tributed in the retina, are subservient to its support, and are 
consequently as visible in the adult as in the fetus; and, where 
the membrane of the retina has been described as adhering to 
the point of the ciliary body, these vessels of the retina unite 
to or inosculate with the vessels of the ciliary processes. 
Walter objects to the description of the arteria centralis re- 
tinae given by Haller and others ; he says, decidedly, that there 
are no arteries distributed to the retina, and that anatomists 
have deceived themselves in supposing those vessels which ra- 
mify on the retina, to be arteries, when, in reality, they are 
veins ; he conceives, that the free return of the injection from 
the extremities of the arteries into the veins has misled them. 
I am at a loss to conceive what notions Professor Walter 
can have entertained regarding this vein distributed in the 
retina, without an accpmpanying artery. It is a supposition 
contrary to the general frame of the economy, and I would 
oppose to it, with confidence, my own experience, since in the 
ox and other animals, I have seen the veins of the retina tur- 
gid with blood and exceedingly distinct; yet, when I injected 
the trunk of the artery at the root of the optic nerve, I found 
a set of vessels injected on the surface of the retina quite dis- 
tinct from the turgid veins, and which could be no other than 
the arteries distributed to the retina. I must conclude that 
there is no peculiarity in the distribution of vessels in the tu- 
nica vasculosa retinae. 
We frequently observe, that the trunks of veins and arteries, 
* See Haller.. Fascic. vii. tab. vi. fig. 2. 4. 7. 
f Haller, F. vii. p. 42. 
\ Walter (de venis ocuU) says, the arteria centralis retinae, having perforated 
the membrana hyoloidea, passes through the middle of the vitreous humour, 
and scatters some twigs on the small cells of the vitreous humour. It does not, 
he says, run through the vitreous humour in a straight line from behind for- 
ward, nor does it divide into a great number of branches in the posterior part 
of the capsule ot the lens, like radii from a centre, as Zinn has described. lie 
asserts that the lens receives its vessels from the investure of the membrana 
hyoloidea, and that they run back from the edge of the lens towards the pys 
terior convexity. OF THE PELLUCID MEMBRANES. 
63 
destined to the same final distribution, take a different course ; 
but in their final distribution, I know no instance in which they 
do not ramify with parallel branches interwoven with each other. 
The vena centralis retina;, as it is described by Haller, 
is sometimes a branch of the ophthalmica cerebralis, but often 
it rises from the cavernous sinus, amongst the origins of the 
external and inferior recti muscles of the eye ; after giving off 
many small twigs to the periosteum and fat of the orbit, it passes 
obliquely from behind, forward and inward, perforates the 
sheath of the optic nerve, and, after supplying the sheath, dips 
into the surface of the nerve.—It is now the comes arteriae 
centralis retinae. It enters through the cribriform plate of the 
optic nerve, and spreading generally in large and remarkable 
branches on the retina, these make free inosculations with 
each other, and finally inosculate with the veins of the ciliary 
processes. 
Whether a branch of the vena centralis retinas is sent off to 
accompany the branch of the artery which takes its course 
through the vitreous humour, I have not been able to determine. 
CHAP. VIII. 
OP THE VASCULARITY OF THE PELLUCID MEMBRANES. 
If we cut through the sclerotic and choroid coat, round the 
optic nerve as it enters the eye, and afterwards cut up the outer 
coats towards the cornea, the humours fall out from these coats, 
and will remain suspended in a fluid, hanging by the optic 
nerve, and closely embraced by the retina: we have now to 
review these parts taken collectively, independent of the out- 
ward and proper coats, and as I have classed them, as consti- 
tuting the internal globe of the eye. 
The first peculiarity which strikes us here is the perfect 
transparency of all the parts within the embrace of the retina. 
As there are, in the adult and healthy eye, no vessels to be 
seen in the transparent membrane and humours, it becomes a 
question, whether nature has provided for the support and 
nourishment of those parts by other means than the common 
circulation of red blood through vessels ? Now, I am inclined 
to think, that there is no such circulation through them; and I 
believe, that this would be much more generally allowed were 
there not something like a proof remaining in men’s minds that 64 
OF THE PELLUCID MEMBRANES. 
these humours and tunics were supplied with red blood in the 
foetus ; whence they deduce the natural consequence that, in 
the adult state, these vessels are only shrunk so as to convey 
only colourless fluids. I have, therefore, to give my reasons 
why I think that these vessels of the foetus are not subservient 
to the humours; and, I think, I shall prove that, when they 
have once disappeared, they are no longer pervious vessels ; 
that, though those parts which they are supposed to supply, 
should become inflamed and vascular in the adult, these ves- 
sels which were apparent in the foetus do not become enlarged ; 
that they do not administer in any way to inflammation and 
disease, but that a new source is given, and that vessels are 
formed which were at no former period discernible. 
Why should there be red blood transmitted to the pellucid 
membranes and humours of the foetus ? Why is not that state 
of circulation, which nourishes and supports the parts in the 
adult state, sufficient for their growth and the progress to per- 
fection which they undergo in the foetus ? Why is the capsule 
of the lens only crowded with vessels carrying red blood, 
while the proof of vessels passing to the cells of the vitreous 
coat stands upon some very rare and vague assertions, and such 
as can be naturally explained by the appearance of those ves- 
sels which merely pass through the vitreous humour for a 
different destination? 
I believe this is a view which has been little attended to ; 
but, upon the most minute inquiry, and upon examining the 
preparations of the vascularity of the eye of the fetus, I can 
see no vessels passing into the humours and carrying red hlood, 
which are not finally distributed to the membrana pupillaris. 
When we lay open the eye of a fetus, after a very minute and 
successful injection, we see vessels which all proceed from the 
centre of the optic nerve, passing through the vitreous humour 
to the back of the capsule of the lens, viz. the branches of 
the arteria centralis retinas. This artery divides very often 
into many branches before it arrives at the capsule of the lens; 
now, if these be filled with blood, or but partially injected, 
they have the appearance of being branches distributed to the 
vitreous humour, and not to the lens, This appearance is still 
more apt to deceive us when the lens is separated from the 
vitreous humour, and when the vitreous humour is otherwise 
disturbed, for then the vessels shrink and seem to terminate in 
the midst of the vitreous humour. When the injection is per- 
fect there is no such appearance. 
On the back of the lens we see a profusion of vessels ; but 
I think I may positively say that these vessels do not penetrate 
to the lens itself, but are merely on the capsule, and that hav- ing made the circuit of the lens, they terminate in the mem* 
brana pupillaris and ciliary body. I can observe no villi on 
the inner surface of the capsule of the lens, nor any appearance 
of its being a secreting surface, to lead me to suppose that 
these vessels secrete the lens, as Walter supposes they do ; 
nor, after the most successful injection of the capsule of the 
lens and of the coats of the eye in general, can I observe the 
slightest stain of colour in the pellucid state of the lens, nor 
betwixt its white fibres when it becomes opaque. Nor have 
I observed, at any time, a single branch of these vessels, which 
are so profuse on the back of the lens, distributed to the ante- 
rior part of the capsule ; on the contrary, they all terminate 
abruptly at that line, a little forward from the utmost verge of 
the lens, where they are united to the vessels of the membrana 
pupillaris and ciliary processes. Were these vessels of the 
capsule provided for the secretion of the lens, or were those 
vessels the trunks of lesser branches, which pierce into the 
substance of the lens, they would appear also on the forepart 
of the capsule. 
If I am accurate in these observations, we are authorized to 
deduce this conclusion :—that these vessels which we see run- 
ning through the vitreous humour and capsule of the lens, and. 
which are sometimes seen filled with red blood or injected 
with size and vermillion, are not the vessels of the humours, 
but vessels in their passage to the membrana pupillaris, and 
that they disappear totally when that membrane is absorbed. 
They are injected when the membrana pupillaris is injected; 
they are more difficult to fill when that membrane is becoming 
pellucid anti tender towards the latter period of gestation; 
and with the annihilation of the membrane follows the disap- 
pearance of the vessels carrying red blood through the trans- 
parent humour of the eye. 
In confirmation of the total annihilation of these central 
vessels of the vitreous humour, I have found that, when disease 
comes upon the lens of the adult, the vessels, which are appa- 
rent in consequence of inflammation, do not proceed through 
the old tract from the centre of the optic nerve and through 
the vitreous humour to the lens, but that they come from the 
extremity of the retina and laterally, and thence spread over 
the back of the lens. 
An eye, which I had lately an opportunity of examining, 
confirmed me in this opinion. I assisted my brother in an ope- 
ration on the eye, in which, the anterior part being diseased, 
it was cut away. I had soon ,an opportunity of retiring and 
examining the parts with Dr. Monro. I observed then an 
opaque spot on the posterior surface of the lens, which was 
OF THE PELLUCID MEMBRANES. 
65 66 
ANATOMY OF THE HUMOURS. 
indeed in the capsule, and to this spot there came vessels over 
the margin of the lens from the extremities of the vessels of 
the retina ; but, in the vitreous humour, there were no vessels 
to be seen, nor any branches passing into the lens obliquely 
from behind, as they do in the foetus. 
CHAP. IX. 
SOME SURGICAL OBSERVATIONS CONNECTED WITH THE 
ANATOMY OF THE HUMOURS. 
I have already mentioned, as the principle of the operation 
of extracting the lens, that the simple action of the muscles, 
surrounding the eyeball, is sufficient to protrude the lens, if 
the incision of the cornea be of proper dimensions relative to 
the size of the lens. No doubt, if there have been thickening 
inflammation, and perhaps preternatural adhesions of the mem- 
branes surrounding the lens, the operation will necessarily be- 
come more complicated; the lens will not glide at once over 
the cheek when the incision of the cornea is completed. But 
still, I think, we are not to allow ourselves to consider it as a 
step of the operation, in any circumstances, that the ball of the 
eye is to be pressed ; because, in that case, the membranes of 
the lens give way suddenly, and part of the vitreous humour 
unavoidably is protruded with it, or the edge of the lens is 
turned obliquely to the pupil, and the vitreous humour escapes 
by the side of it. It is better to destroy the adhesions with 
the instrument, and to scratch the capsule of the lens so that it 
may burst. Whence it is evident that it is necessary, in order 
to insure the correct performance of the operation of the extrac- 
tion, that the lens should press equally forward on the pupil, 
and that the pupil should be allowed to dilate. From this it 
appears, how loose the ideas of those are who can speak of try- 
ing first to couch, and if that is not found to succeed, then to 
perform the operation of extraction. I conceive the attempt 
with the needle to preclude the operation of extracting, for 
these reasons :—An unsuccessful attempt to depress will, in 
general, be a laboured and reiterated motion of the point of 
the needle, which must occasion inflammation, and an adhesion 
firmer than is natural. Again, in couching, the lens is removed 
from the axis of the eye so far only, that, in the case of the ANATOMY OF THE HUMOURS. 
67 
extracting being attempted, it no longer equally opposes itself 
to the pupil, the consequence of which must be, the escape of 
the vitreous humour and the detention of the lens. 
In regard to the place at which the couching needle is to be 
introduced, we may observe, that we are directed by the older 
surgeons, to pierce the sclerotic coat very near to the edge of 
the cornea, because they were afraid of hurting the lens with 
the needle! The idea then entertained was, that the cataract 
was a membrane hung behind the pupil and before the lens. 
The older surgeons had the idea that the needle entered be- 
fore the lens, and passed at once into the aqueous humour. 
We are to disregard these injunctions of surgeons who directed 
the needle to be introduced with the idea of avoiding the lens; 
for, while their notions regarding the disease were erroneous, 
their rules of operating could not be correct; accordingly, we 
find them differing in their directions as to the place of 
piercing the cornea; some directing us to pierce it at the dis- 
tance of one line from the edge of the cornea, others at the 
distance of four lines and a half. 
Now that we know the place of the cataract, and know also 
that it is the opaque lens, we can be at no loss to introduce the 
needle correctly. If, says M. Petit, we pierce the sclerotic 
coat one line from the edge of the cornea, we pierce the tu- 
nica conjunctiva, sclerotica, choroid, vitreous humour, and 
ciliary processes before the needle enters the cataract. In this 
puncture, we wound the most vascular part, and, indeed, every 
delicate part of the eye; for even in this most anterior course, 
the retina is equally lacerated with the others.* But if we 
pierce the sclerotic coat, three lines from the edge of the cor- 
nea, we avoid the ciliary ligament and body, and processes; 
and by directing it a little forward, in a line towards the oppo- 
site margin of the iris, we shall find the point of the needle 
advancing through the opaque lens; for, although the lens be 
so far opaque as to prevent the light from striking the retina, 
it is so far transparent, in general, that the needle is distinctly 
seen entering its substance, and can be then directed, so as to 
transfix the cataract without hurting the iris. 
We have seen that there is no posterior chamber of the 
aqueous humour fit to contain the depressed crystalline lens. 
The belief, which even some modern surgeons have entertain- 
ed, of the possibility of depressing the lens into the, aqueous 
humour, is a remnant of those inaccurate notions respectingthe 
size of the posterior chamber of the aqueous humour and the 
* In our most modern system of surgery, vve are directed to enter the needle 
one-tenth of an inch. To my certain knowledge, not only the ciliary body 
has been injured by this direction, but even the root of the iris has been seen 
tb be pushed forward on the point of the needle. 68 
ANATOMY OF THE HUMOURS. 
place of the lens, which have long been corrected. With this, 
also, I think ought to have been forgotten, the idea of the 
rising of the lens after it has been depressed by the cataract 
floating in the humours.—The fact, I am confident,, is this: 
when, after transfixing the cataract, we endeavour to dislodge 
it by depressing the point of the needle, we separate the ad- 
hesion between the humours and the points of the ciliary pro- 
cesses ; we do not, however, unsocket the lens from the fore- 
part of the vitreous humour, but when the lens descends with 
the point of the needle, from before the pupil, the vitreous 
humour revolves with it; the consequence of which is, that 
when the needle is withdrawn, the lens rolls rounds with the 
vitreous humour : but as the lens only is opaque, as its firm 
connection with the vitreous humour, and even the rolling of 
the vitreous humour itself cannot be seen, this rolling of the 
lens appears to be the consequence merely of its own buoy- 
ancy in the aqueous humour. This adhesion of the lens to the 
vitreous humour, I have been sensible of during its depression, 
from the elastic nature of the resistance which I felt. When 
the lens parts from its socket in the vitreous humour, and when 
it is depressed with such a turn of the needle as puts it under 
the anterior part of the vitreous humour, it cannot rise again; 
there is no motion of the eye which can replace it—there is 
no aqueous fluid in which, if it were of less specific gravity, it 
could rise; it lies under, and, in part, imbedded in the vitreous 
humour. Another idea is, that it rises with the needle : but 
no one, w'ho understands what is to be done in the operation 
of the needle, will raise it again opposite to the pupil after the 
lens is depressed—it ought to be withdrawn without again ele- 
vating the point. But what has always appeared to me as the 
most unaccountable cause that can be assigned for the rising 
of the cataract, is the action of the muscles of the eye.* It 
has been explained how the lens is protruded by the action of 
the muscles when the cornea is cut and the aqueous humour 
let out, for then the uniform resistance of the eye is broken, 
and there is a motion of the humours towards the breach; and 
the lens lying behind the pupil, is the first part to be protruded 
forward ; but when it lies under the anterior part of the vitre- 
ous humour (and there it must lie if it is at all displaced,) or 
in whatever situation it happens to be, from that it cannot be 
moved by the action of the recti muscles ; for they embrace 
the eye on every side, and their action operates uniformly, so 
that they cannot affect a body immersed in the midst of the 
humours. For the same reason that we should decline the 
operation of extracting, after attempts have been made to de- 
* See Mr. Benjamin Bell’s Systenj of Surgery. ANATOMY OF THE HUMOURS. 
69 
press with the needle, I should refuse when the pupil is rugged 
and irregular, because the disease may be more extensive than 
it appears to be. Thus cataracts brought on by falls, or blows, 
or punctures of the eye, are less favourable, as there is danger 
of the inflammation having gone deep, and having affected the 
other humours in a way which cannot be known, since the 
opaque lens is betwixt us and them. 
A frequent cause of the failure of the operation of depres- 
sion is displacement of the lens backwards ; for when it 
seems to have gone down with the needle, it has slipped from 
under it and started backward. In this case the pupil appears 
clear, but the patient gains little advantage ; for the cataract, 
though removed from the pupil, is still in the situation to ob- 
struct the light. 
CHAP. X. 
OF THE MANNER IN WHICH THE EYE ADAPTS ITSELF TO THE 
DISTANCE OF OBJECTS. 
This is a question which many have endeavoured to deter- 
mine, and many have failed ; the proof of this is, that there 
is not one explanation of the manner in which the eye adapts 
itself to the distance of objects, but many explanations equally 
ingenious. 
One opinion is, that the eye is at rest when we see the dis- 
tant parts of a landscape, but that the direction of the eye to 
the nearer objects is attended with an 'effort. This effort is 
the action of the straight muscles of the eye compressing the 
ball of the eye, so as to lengthen the axis as much as is ne- 
cessary to allow the pencils of rays to unite in points upon the 
retina. 
To this opinion it is objected, that in some animals the 
sclerotic is hard, and not capable of changing its figure ; that 
in man, the pressure would be unequal; that the unelastic re- 
tina would be thrown into irregular folds ; that these muscles, 
being voluntary muscles under the will, we should be more 
conscious of their operation than we are ; and that, while the 
mind remains attentive to distant objects, no voluntary exer- 
tion of these muscles can affect the distinctness of the objects. 70 
DISTANCE OF OBJECTS. 
Again, to make the eye change its accommodation from the 
distinct vision of objects, at six inches to fourteen feet five 
inches, would require such a pressure as might lengthen the 
axis of the eye one-tenth part, which again would form an 
oval that would derange the retina. 
Another opinion is, that when the eye sees the nearest ob- 
jects it is at rest, and that, in attending to distant objects, the 
straight muscles draw back the forepart of the eye into the 
socket, and thus shorten the axis. To this opinion, of course, 
the same objections lie as to the supposition that the axis is 
lengthened by the operation of the muscles. 
There are some who have entertained an opinion, that the 
iris, by its contraction, operates so on the circular margin of 
the cornea, where it is connected with the sclerotic coat, as to 
make the cornea more convex, and thus increase its power of 
concentrating the rays, and enable the eye to see near objects 
distinctly. To account for this power in the iris, Dr. Jurin, 
the proposer of this hypothesis, supposes that there is a 
greater muscular ring in the margin of the iris connected with 
the edge of the cornea ; the existence of these muscular fibres 
is not demonstrated, but he says, since the lesser muscular 
ring in the inner margin of the iris is not proved by ocular 
inspection, and yet is justly inferred from its effects, viz. the 
contraction of the pupil; in the same way, “ the change of 
“ conformation in the eye has not yet been adequately ac- 
“ counted for, but may be fairly made out by supposing the 
u existence of the greater muscular ring.” His conclusion 
is in these words:—“ When we view objects nearer than the 
“ distance of 15 or 16 inches, I suppose the greater muscular 
“ ring of the iris contracts, and thereby reduces the cornea 
“ to a great convexity; and when we cease to view these 
“ near objects, this muscular ring ceases to act, and the cor- 
“ nea, by its spring, returns to its usual convexity suited to 
“ 15 or 16 inches. In which condition the elasticity of the 
“ cornea on the one side, and the tone of the muscular ring 
u on the other, may be considered as two antagonists in a 
u perfect equilibrium.” 
To this opinion it is objected, that the iris is not rooted in 
the cornea, but in the sclerotic coat, which is firm in man, and 
inflexible in many animals. We have also to consider, that 
this delicate and invisible circle of muscular fibres has not only 
to contract the margin of the cornea, blit, in this action, to 
alter the configuration of the whole eye. The eyeball is a 
whole equally distended, and no part of it can suffer contrac- 
tion without a resistance from the whole of the coats : besides, 
in this case, the alternation of light and the brightness of ob- DISTANCE OF OBJECTS. 
71 
jects would be perpetually obscuring the image, by the play 
of the iris causing an alteration of the focus of the cornea. 
But Dr. Jurin did not attribute the whole effect to the action 
of the iris. He thus explains the use of the fluid surrounding 
the lens and the membranous capsule :—When the eye is to 
be suited to greater distances, he supposed that the ligamen- 
tum ciliare contracts its longitudinal fibres, and, by that 
means, draws the part of the interior surface of the capsule, 
into which these fibres are inserted, a little forward and out- 
ward. By this action, he supposed that the fluid, within the 
capsule of the lens, flows from the middle towards the mar- 
gin ; and, consequently, the centre of the capsule of the lens 
is reduced to a less degree of convexity; and that the elasti- 
city of the capsule, and the tone of the ligament, may be 
looked upon as two antagonists perfectly in equilibrio with 
one another. In the state of rest the eye is conceived, by Dr. 
Jurin, to be adapted to the middle distance ; by the increase 
of the convexity of the cornea, to be adapted to nearer vision ; 
and by the change in the capsule of the lens, to be fitted to 
distant objects. 
To this last supposition it is objected, that there is a sim- 
plicity in the operations of nature; that the change wrought 
upon the capsule of the lens is insufficient to account for the 
whole effect, and that, therefore, there is a presumption that it 
has no share in producing the change ; that there are no mus- 
cular fibres in the ciliary processes ; and, lastly, that this fluid, 
being of density, but little, if at all, removed from the aqueous 
humour, any alteration of its form can have but a very insig- 
nificant effect. 
It has occurred to others,* that the oblique muscles of the 
eyeball, being thrown in opposite directions round it, they 
may have the effect of elongating the axis of the eye: Again, 
that the action of the orbicularis muscle of the eyelid by 
compressing the eyeball, assists in accommodating the eye 
for seeing near objects more distinctly. Dr. Monro makes a 
set of experiments to prove the effect of the orbicularis muscle 
of the eyelids ; but I conceive that he has deceived himself, 
in ascribing to the compression of the eyelids an effect partly 
produced by a voluntary effort, but in a way which is not un- 
derstood, and partly by the contraction and dilatation of the 
pupil, from the degree of opening of the eyelids. If he be right 
in his way of accounting for the effects produced in the expe- 
riments which he details, they ought to have the effect of pre- 
cluding the necessity of all further hypothesis ; so fully does 
* Hambergerus, Briggs, Kei!, Monro. 72 
DISTANCE OF OBJECTS. 
the action of the orbicularis muscle seem to him adapted to 
the end proposed. In the first experiment, when he opened 
his eyelids wide, and endeavoured to read a book, the letters 
on which were so near the eye as to be indistinct, he found 
that he could not do it. In the second experiment, keeping 
the head in the same relation to the book, he brought the 
edges of the eyelids within a quarter of an inch of each other, 
and then made an exertion to read, when he found he could 
see the letters and words distinctly. When I try this experi- 
ment I find the action of the eyelids to have no sensible effect, 
unless they are brought very close together: then I do indeed 
find that they have a most remarkable effect. But in this situa- 
tion, the eyelids cover the cornea so much, that if they have 
any effect at all upon the cornea, it must be to compress and 
flatten it, and not to give it a greater convexity. The smaller 
the opening of the eyelids, the greater I found the effect; I 
conceive it to be produced by the optical effect of the eye- 
lashes correcting the too great converging of the rays ; and the 
same effect I found to be produced by the marginal hairs of 
two flat camel-hair brushes, although the eyelids were kept 
open. Dr. Monro concludes that, in this action of the eye, 
1st, the iris, 2dly, the recti muscles, 3dly, the two oblique 
muscles, and 4thly, the obicularis palpebrarum, have all their 
share in accommodating it to the distance of objects, and in 
giving perfect vision. 
Very ingenious experiments are made by Dr. Young,* to 
determine whether there be any change in the length of the 
axis of the eyeball. He considers it as necessary to account 
for the power of the eye in adapting it to the distance of ob- 
jects, that the diameter should be enlarged one-seventh; its 
transverse diameter diminished one-fourteenth; and the semi- 
diameter shortened one-thirtieth of an inch. To determine 
this he fixed the eye, and at the same time he forced in upon 
the ball of the eye the ring of a key, so as to cause a phantom 
very accurately defined to extend within the field of perfect 
vision; then looking to bodies at different distances, he ex- 
pected if the figure of the eye was altered, that the spot, 
caused by the pressure, would be altered in shape and dimen- 
sions ; he expected that instead of an increase of the length of 
the eye’s axis, the oval spot caused by the pressure of the key, 
resisting this elongation, should have spread over a space at 
least ten times as large as the most sensible part of the retina : 
but no such effect took place ; the power of accommodation 
was as extensive as ever, and there tvas no perceptible change 
' Philos. Trans, for 1810- DISTANCE OF OBJECTS. 
73 
» either in the size or in the figure of the oval spot. Again, he 
placed two candles so as exactly to answer to the extent of the 
termination of the optic nerve: he marked accurately the point 
to which the eye was directed; he then made the utmost 
change in its focal length, expecting that, if there were any 
elongation of the axis, the external candle would appear to 
recede outward upon the visible space; but this did not hap- 
pen; the apparent place of the obscure part was precisely the 
same as before. 
A favourite opinion of late has been, that the lens has a 
power of altering its degree of convexity, and thus accommor 
dating itself to the distance of objects. As to the fibrous 
structure of the lens, there can be no doubt: first, it is rent by 
fissure, then split into lamina, and can be finally teased out 
into fibres. 
This structure was first observed by Leuwenhoeck ; he has 
these words:—u Porro vidi corpus cristallinum ex tarn tenui- 
u bus coacervatis constare squamis ut ubi eas oculo dimetior, 
a dicere cogar, pluris bis millenis sibi invicem incumbere; 
44 ubi enim corpus cristallinum ab ejus membranula seperas- 
“ sem, ejus adhuc axis, ubi crassissimum erat, (non enim est 
a perfecte rotundum, sed aliquo modo planum) duas tertias 
u pollicis partes retinebat; ergo a centro ad circumferentiam 
a est tertia pollicis pars atque quoniam, ex dimensione mea 
u 600 pili lati pollicis quadrati,longitudinem conficiunt 200 pili 
iC lati pollicis tertiam partem adsequare debent. Atque nunc 
44 video ubi dense squamae sunt coacervatse, eas capilli nostri 
44 diametrum nondum adsequare; ergo his 10 cum 200 multi- 
44 plicatis, sequetur, ut dictum, plures 2000 squamas in corpore 
44 cristallino esse coacervatas. Porro vidi singulas has squamas 
44 ex filamentis, concinno ordine juxta se positis, constare adeo 
44 ut singulse squamulse unum filamentum sint crassse ; & ut 
44 hanc substantiam fibros earn ex qua corpus cristallinum con- 
44 stat ob oculos ponerem, earn lineis in circulum ductis quan- 
44 turn pote clesignavi.” 
The fibrous structure and muscularity of the lens was brought 
forward by Descartes, as explaining some actions of the eye ; 
but was again neglected, till more lately, that it has been re- 
vived by the insertion of Mr. Young’s Observations on Vision, 
in the Philosophical Transactions.* The following are Mr. 
Young’ observations on the appearance of the lens:—44 The 
44 crystalline lens of the ox is an orbicular convex transparent 
44 body, composed of a considerable number of similar coats, 
•4 of which the exterior closely adheres to the interior. Each 
' See vo!. for 179,S. 74 
DISTANCE OF OBJECTS. 
“ of these coats consists of six muscles, intermixed with a ge- 
“ latinous substance, and attached to six membranous tendons. 
“ Three of the tendons are anterior, three posterior; their 
“ length is about two-thirds of the semidiameter of the coat; 
“ their arrangement is that of three equal and equidistant raysr 
“ meeting in the axis of the crystalline ; one of the anterior is 
“ directed towards the outer angle of the eye, and one of the 
“ posterior towards the inner angle, so that the posterior are 
“ placed opposite to the middle of the interstices of the ante- 
“ rior; and planes passing through each of the six and through 
u the axis, would mark on either surface six regular equidistant 
“ rays. The muscular fibres arise from both sides of each 
“ tendon ; they diverge till they reach the greatest circumfer- 
“ ence of the coat, and having passed it, they again converge 
“ till they are attached respectively to the sides of the nearest 
“ tendons of the opposite surface. The anterior or posterior 
“ portion of the six viewed together, exhibits the appearance 
“ of three penniforme-radiated muscles. The anterior tendons 
“ of all the coats are situated in the same planes, and the pos* 
“ terior ones in the continuations of these planes beyond the 
“ axis. Such an arrangement of fibres can be accounted 
“ for on no other supposition than that of muscularity. The 
“ mass is inclosed in a strong membranous capsule, to which it 
“ is loosely connected by minute vessels and nerves ; and the 
“ connection is more observable near its greatest circumference. 
u Between the mass and its capsule is found a considerable 
“ quantity of an aqueous fluid, the liquid of the crystalline.” 
FIBROUS STRUCTURE OF THE LENS. 
Fig. 14. 
Fig. 15. 
Mr, Young’s fig. 
Leuwenhoeck’s fig. 
Supposing that these are muscular fibres, from their close- 
ness and direction, they would stand acknowledged as forming 
the strongest and most powerful muscle of its size in the whole DISTANCE OF OBJECTS. 
75 
body; yet they act only on themselves, which requires the 
least possible degree of power. Again, how are they relaxed? 
What power is their antagonist? Mr. Young demonstrates 
not only the muscular fibres, but the tendons of the lens;* as 
if it were not evident that the lens acted merely on itself, 
which could require no concentrating of its fibres into tendons ; 
for tendons are found in other parts of the body only where it 
is necessary to concentrate the whole power of the muscle so 
as to operate on one point. 
We learn from Mr. Home,f that Mr. John Hunter had 
proved the lens to be laminated, and those laminae to be com- 
posed of fibres ; and upon the same authority, we learn that 
his opinion was in favour of the muscularity of its structure. 
Mr. Home wished to follow out this subject, by including it in 
the Croonian Lecture. Mr. Home found, with the assistance 
of Mr. Ramsden, that a patient, after the extraction of the 
cataract, still retained the power of adapting the eye to the 
distances of objects. Indeed, we must be well aware, that if a 
patient, after couching and extracting the lens, could only see 
at one given distance, an effect so very particular must have 
been long since observed. This was a conviction to Mr. 
Home and Mr. Ramsden, that the investigation was to be no 
further pursued in this tract, and they turned their attention, 
therefore, to the cornea. 
Mr. Ramsden contrived an apparatus which, if the gentle- 
men engaged in the experiments have not deceived themselves, 
must put this question at rest. By Mr. Ramsden’s ingenious 
contrivance, the head was fixed accurately, and at the same 
time a microscope was adapted to observe the changes in 
the convexity of the cornea, as the eye was directed alter- 
nately to near and to distant objects. In these experiments, 
the motion of the cornea became distinct, its surface remained 
in a line with a wire which crossed the glass of the microscope 
when the eye was adjusted to the distant objects, but pro- 
jected considerably beyond it when adapted to the near ones, 
and the space through which it moved was so great as readily 
to be measured by magnifying the divisions on the scale, and 
comparing them. In this way it was estimated that it moved 
the 83.0th part of an inch (a space distinctly seen in a micros- 
cope magnifying 30 times,) in the change from the nearest 
point of distinct vision to the distance of 90 feet. 
In the evidence from anatomical structure, I cannot think 
Mr. Home so happy. He was desirous of determining more 
accurately than had hitherto been done, the precise insertion 
* See Philos. Trans. 
fIbid. 76 
DISTANCE OF OBJECTS. 
of the tendons of the four straight muscles, so as to know 
whether their action could be extended to the cornea or not; 
he found them to approach within } of the cornea before their 
tendons became attached to the sclerotic coat. But he did 
not stop here—he stripped off with them the anterior lamina 
of the cornea. Now as it is supposed, in these experiments, 
that the action of the i*ecti muscles upon the sides and back 
part of the ball compresses the humours, and makes them 
flow forward so as to distend the cornea ; if the extremities 
of the tendons be inserted into the edge of the cornea and 
even pass over it, as Mr. Home has demonstrated, their effect 
would be to flatten the cornea, by drawing out and extending 
its margin. This is a circumstance which Dr. Monro has 
remarked; and Dr. Monro has also, with more accuracy of 
observation,found “all the tendinous fibres of the recti muscles 
firmly attached to the sclerotic coat at the distance of a quarter 
of an inch from the cornea, and no appearance that any part 
of them, or that any membrane produced by them, is con- 
tinued over the cornea.” 
Amongst the variety of opinions, the innumerable, ingeni- 
ous, but contradictory experiments for discovering the manner 
in which the eye adapts itself to the distance of objects, I am, 
for my own part, jnuch at a loss to determine which I should 
prefer. I have often doubted whether these experimenters 
were not in search of the explanation of an effect which has 
no existence. I have never been able to determine, why a 
very slight degree of convexity in the cornea of a short-sighted 
eye should be so permanent during a whole lifetime, notwith- 
standing the perfect elasticity of the cornea, and its being so 
adapted as to alter its convexity by the action of the muscles. 
Again, a near-sighted person, with the assistance of a con- 
cave glass, can command the objects to the distance of some 
miles, and with the glass still held to his eye, can see minute 
objects within three inches of the eye. Now I cannot con- 
ceive how the concave glass should give so great a range to the 
sight: as there can be no change in the glass, it must be the 
eye which adapts itself to the variety of distances ; yet, with- 
out the glass it cannot command the perfect vision of ob- 
jects for a few feet. Again, a short-sighted person sees an 
object distinctly at three inches distant from the eye ; at 12 
feet, less distinctly; and when he looks upon the object at 12 
feet, the objects beyond it are confused, just as in other men’s 
eyes ; but when he directs his attention to the more remote 
objects, those nearer become indistinct. Now this indistinctness 
of the object, seen when he examines narrowly the objects 
beyond them, would argue (did we admit this muscular power DISTANCE OF OBJECTS. 
77 
in the eye of adapting itself to objects,} that the cornea or the 
lens has become less convex, were we not previously con- 
vinced that the utmost powers of the eye could not bring the 
object at the distance of 12 feet, or any other intermediate 
distance, to be more distinctly seen than the fixed and perma- 
nent constitution of the eye admits. 
I cannot help concluding, therefore, that the mechanism of 
the eye has not so great a power of adapting the eye to various 
distances as is generally imagined, and that much of the effect 
attributed to mechanical power is the consequence of attention 
merely. An object looked upon, if not attended to, conveys 
no sensation to the mind. If one eye is weaker than the other, 
the object of the stronger eye alone is attended to, and the other 
is entirely neglected : if we look through a glass with one eye, 
the vision with the other is not attended to. Now, objects, as 
they recede from us, become fainter and fainter in their co- 
lours, and the general effect upon the eye is different from those 
which are near; and as it happens that the mind must associ- 
ate with the sensation before it be perfect, there is, conse- 
quently, an obscurity thrown over distant objects when we con- 
template near ones ; as, on the other hand, the images of near 
ones are not attended to when the mind is occupied with dis- 
tant ones, although they be nearly in the line with the dis- 
tant object examined. 
CHAP. XI. 
OF SEEING IN GENERAL 
The eye is certainly the noblest of the organs of sense. 
It is that with which we should part the most unwillingly, and 
of which when deprived we are most helpless. A celebrated 
philosopher says, how much more noble is that faculty by which 
we can find our way in the pathless ocean, traverse the globe, 
determine its figure and dimensions, delineate every region of 
it; by which we can measure the planetary orbs, and make dis- 
coveries in the sphere of the fixed stars ! Again, how admira- 
ble is that organ by which we can perceive the temper and dis- 
positions, the passions and affections of our fellow creatures ; 
and, when the tongue is taught most artfully to lie and dissem- 
ble, the hypocrisy is discovered in the countenance! We of- 
ten are able to detect what is crooked in the mind as well as 78 
Or SEEING IN GENERAL. 
in the body ! Yet, notwithstanding the perfection of the sense 
of seeing, much of tliis perfection is gained by the other 
senses, and particularly by that of touch. If the human body 
were motionless and inert, the sensation conveyed by the eye 
would be very imperfect; we should be able to conceive nei- 
ther the distance nor the figure of objects. But, as it is, the 
distance of the object, joined with its visible magnitude, is the 
sign of its real magnitude ; and the distance of the several 
parts of an object, joined with its visible figure, becomes a 
sign of its real figure. Without this combination of the ori- 
ginal sensation with the acquired perception, we should see 
form and colour without having any idea of its distance, or of 
the convexity of an object; we should have no measure of its 
length, or breadth, or distance. 
Upon other occasions, we are apt enough to acknowledge 
the powers of association. But the connection of ideas is in 
no instance more constant and secret than in the ideas convey- 
ed by sight and touch. When a solid body is presented to 
view, we see only the light and shade ; but this raises in our 
mind the associated ideas from the sense of touch, viz. soli- 
dity, convexity, and angularity, “ the visible idea exciting in us 
u those tangible ideas,” which, in the free and promiscuous 
exercise of our senses, usually accompany it. It is thus that 
we attribute to the sense of sight what is the act of the me- 
mory and judgment.* 
WTe have seen that the picture of an object is formed in the 
bottom of the eye. It was formerly sufficient to say, that the 
mind contemplates this image. We should say now, that this 
image is conveyed into the sensorium by the optic nerve. This 
is an hypothesis merely; and we have no more consciousness 
of the object being in the brain or sensorium, than in any other 
part of the body; we may rather say, that the impression 
made on the organ, nerves, and brain, is followed by sensa- 
tion, and that the intelligence is the joint operation of the 
whole.f Lastly, the metaphysician calls our sensations the 
signs of external objects ; because the object itself is not pre- 
sented to the mind, nor is there an actual resemblance betwixt 
* See Dr. Jurin on Mr. Molyneux’s problem, Smith’s Append, p. 27. 
f Euclid, and others of the ancients, contended that vision was occasioned 
by the emission of rays from the eye to the object. He thought it more natu- 
ral to suppose, that an animate substance gave out an emanation, than that the 
inanimate body did. In 1560, the opinion was confirmed that the rays entered 
the eye.—The sensation was not always believed to be in the retina : it was 
by some believed that part of the sensation was to be attributed to the crys- 
talline. Kepler, in in 1600, showed, geometrically, how the rays were refract- 
ed through all the humours of the eye so as to form a distinct picture on the 
retina; and also he showed the effect of glasses on the eyes. See further, re- 
garding the opinions of the ancients, Boerhaave Prelect. Acad. tom. iv. p. 282. OF SEEING IN GENERAL. 
79 
the object and the sensation of it, but merely a connection es- 
tablished by nature, as certain features are natural signs of an- 
ger ; or by art, as articulate sounds are the signs of our thoughts 
and purposes. 
We are now naturally led to the consideration of some 
points, the full comprehension of which require the know- 
ledge, both of anatomy and of the principles of optics. 
PARALLEL MOTION OF THE EYES. 
The axis of the eye is a line drawn through the middle ot 
the pupil and of the crystalline lens, and which consequently 
falls upon the middle of the retina; and the axes of both eyes 
produced, are called the optic axis. But the axes of the eyes, 
it is evident, are not always parallel; for when both eyes are 
directed to a near object, the axes of the eyes meet in that ob- 
ject ; but when we direct the eyes to the objects in the hea- 
vens, they may be considered as perfectly parallel in their axis, 
though perhaps not then mathematically so. To an observer, 
the eyes seem always moving in parallel directions ; but nature 
has given us the power of varying them so, that we can direct 
them to the same point, whether remote or near. This, how- 
ever, is in some measure learnt by custom, and lost by disuse. 
A child has much difficulty in altering the distance of its eyes, 
which is the occasion of the vacancy of its stare : and again, 
we observe that a patient who has long lost one eye, is incapa- 
ble of directing the axis of the blind eye without looking with 
the other, and even then, the blind organ does not follow the 
other with that perfect accuracy which exercise gives when 
both eyes are sound. By much practice and straining, the 
axes of the eyes may be much further altered from the natural 
parallelism, which wags and boys often do, so as to distort 
the eyes, and give a droll obliquity to the countenance. 
Still, custom alters the direction of the axis of the eyes but 
a very little; for the natural constitution of the eye does not 
allow the child to turn his eyes in every different direction 
from each other. There is, on the contrary, as we have seen, 
a particular sensible spot in the retina, which makes it neces- 
sary to distinct vision, that this spot shall receive the concen- 
trating rays of light; and the natural constitution of both 
eyes, is, that this spot in each eye shall have such a relation to 
that of the other, that the axis of both should be accurately in 
the middle of the eyeball in order to produce single vision. 
By voluntary squinting or depressing one of the eyes with 
the finger, objects appear double, because the optic axis is 
changed in the distorted or depressed eye, and the picture is 80 
no longer painted on corresponding points of both. This 
simple experiment leads us to consider what is the constitu- 
tion and correspondence of the eyes, that when each has the 
picture of the object impressed upon it, we should only see it 
single if the eyes are sound and perfect. 
or seeing ix general. 
Fig.iG. 
F&17- 
For example, the object A, in fig. 16, is exactly in the cen- 
tre of the axis of both eyes, consequently, it is distinctly seen ; 
and it appears single, because the rays from it strike upon the 
points of the retina opposite to the pupils in both eyes. Those 
points have a correspondence; and the object, instead of ap- 
pearing double, is only strengthened, in the liveliness of the 
image. Again, the object b will be seen fainter, but single, 
and correct in every respect. It will appear fainter because 
there is only one spot in each eve which possesses the degree 
of sensibility necessary to perfect vision : and it will appear 
single, the rays proceeding from it having exactly the same 
relation to the centre of the retina in both eyes. Though they 
do not fall on the centre of the retina, they fall on the same 
side of the centre in both eyes. But if the eyes are made to 
fix stedfastly on an object, and if another object should be 
placed before the eyes within the angle which the axis of the 
two eyes make with the first object, it will be seen double, 
because the points of the retina struck by the rays proceeding 
from the nearer object do not correspond in their relation to 
the central point of the retina. Thus, the eyes b b, fig. 17, 
having their axis directed to a, will see the object c double 
somewhere near the outline u d. Because the line of the di- 
rection of the rays from that body c, do not strike the retina in 
the same relation to the axis a b in both eyes. Upon this prin- 
ciple, we may easily explain why objects, which are much OF SEEING IN GENERAL. 
81 
nearer the eyes, or much more distant from them than that to 
which the two eyes are directed, appear double. Thus, if a 
candle is placed at the distance of ten feet, and I hold my 
finger at arm’s length between my eyes and the candle, when 
I look at the candle, I see my finger double, and when I look 
at my finger, I see the candle double. This double vision oc- 
curs to us all frequently ; but unless we make the experiment 
purposely, we do not attend to it. Many other instances of 
the harmony, and of the want of it, in the eyes, particularly 
the reverse of what these diagrams show, may be easily pro- 
duced, viz. the seeing two objects single: for, if we look at a 
half-penny and a shilling, placed each at the extremity of two 
tubes, one exactly iji the axis of one eye, and the other in the 
axis of the other eye, we shall see but one piece of coin, and 
of a colour neither like the shilling nor like the half-penny, but 
intermediate, as it the one were spread over the other. 
This relation and sympathy between the corresponding 
points of the two eyes, is, therefore, to be considered as a 
general fact, viz. that pictures of objects falling upon corre- 
sponding points of the two retinas, present the same appearance 
to the mind as if they had both fallen upon the same point of 
one retina; and pictures upon points of the two retinas which 
do not correspond, and which proceed from one object, present 
to the mind the same apparent distance and position of two 
objects, as if one of those pictures were carried to the point 
corresponding with it in the other retina. 
Several animals, we see, direct their eyes by very different 
laws from those which govern the motion of ours ; but we are 
not to reason upon their sensations by the laws of vision of the 
human eyes : we must take it as a principle, that nature has 
been bountiful to them also; and that the result of organiza- 
tion in their eyes is perfect vision. 
In birds, (il we except the owl,) the eyes diverge, and are 
directed to opposite sides. As the owl seeks his prey in the 
night, it may be necessary to the distinctness of his vision in 
weak light, that both eyes be directed to the object. Most 
fishes have their eyes directed laterally, though there are ex- 
ceptions ; as those fishes which are flat, and swim at the bot- 
tom, have their eyes’ directed upward. In many insects, the 
surface of the eye has no resemblance of the cornea of vivipa- 
rous animals ; but when examined with the microscope, it is 
seen to consist of a number of tubercles, each of which is a dis- 
tinct eye. In others the eye is removed to the extremity of 
the moveable Very large animals, as the whale, 
elephant, rhinoceros, hippopotamos, have, in proportion to 
their bodies, very small eyes : so have the animals which live 82 
OF SEEING IN GENERAL. 
much under ground ; and, in general, a large eye is a sign of 
the animal being able to see in obscure light, because there is 
proportionably a greater number of rays admitted into the eye. 
For the same reason fishes have a peculiarly large eye and di- 
latable pupil, because the water is a more obscure medium, 
and, from the occasional roughness of its surface, much dark- 
ened and variable. 
We must conclude, that in these varieties of the eyes, where 
there is a difference in number, position, and natural motion, 
there are different laws of vision adapted to these peculiarities 
and the exigences of the animals. If we are to judge from 
analogy, we may suppose, that in many animals, there is no 
correspondence between points of the two retinas, or it is of a 
different kind from ours. In those which have immoveable 
eyes, the centre of the two retinas will not correspond so as to 
give the idea of one object, but of distinct objects, and in their 
respective places. In other animals, corresponding points 
would give false appearances; and in such as turn their eyes 
in all directions, independently of each other, they would 
seem to possess a perception of the direction in which they 
move them, as we have of the motion of our arms. 
SQUINTING. 
We have seen, that there is a point in both retinas more 
acutely sensible to the impression of light and the image of 
objects, than any other part of all its concave surface. In a 
sound eye, this point is immediately opposite to the pupil. 
There is a coincidence betwixt this point and the axis of the 
eye; and when we look to an object, its image strikes this 
point of the retina : but if it should happen that this sensible 
point of the retina should be changed, and not be exactly op- 
posite to the pupil when the axis of the eye is in the line with 
the object, there will be an effort of the muscles moving the 
eyeball to turn, so that the rays proceeding from the object 
shall strike upon the more sensible spot of the nerve.* Again, 
if the greater sensibility of the nerve should lie in its proper 
place, and a remote cause should occasion such an action of 
the muscles and distortion of the eye as we see in a squint, then 
the image will be double, for it no longer falls on correspond- 
ing points of the retina of each eye, and separate images are 
conveyed to the brain. If, however, this distortion continues, 
* This was M. de la Hire’s opinion.—He had* an idea also that squinting 
was produced by the obliquity of the object. Both of these opinions are re- 
futed by Dr, Jurin, OF SEEING IN GENERAL. 
83 
the single vision is gradually restored. Is there, then, in this 
case produced a new correspondence betwixt points of the re- 
tina which were before discordant? We find that this is not 
the case, by a very simple experiment. In a person who squints, 
one of the eyes is directed to the object and the other appears 
to be turned from it: if the sound eye be shut, and the person 
be directed to look to an object with the other, it is directed 
to it with the proper and natural axis. Now this shows us 
that the sensibility of the proper spot in the bottom of the eye 
is not lost. We must explain the single vision in eyes, one 
of which is distorted from its natural axis upon another princi- 
ple. Most people who squint, have a defect in one eye, and 
this is the distorted eye, while the other is directed in the true 
axis to the object. Now the mind does not attend easily to 
two impressions, the one being weaker than the other: in a 
short time the weaker impression is entirely neglected, and the 
stronger only is perceived.—So in squinting, the impression 
©n the weak eye in a short time ceases to be attended to, the 
strong and vivid impression is alone perceived, and single 
vision is the consequence. It is evident, then, that those who 
squint must have a degree of imperfection in the strength of 
the image; for it is necessary to neglect the impression of one 
eye, to obtain distinct vision with the other; the consequence of 
this is frequently an attempt still further to distort the eye, and 
turn it so far inward or under the upper eyelid that no distinct 
impression can be received upon it: at all events they perceive 
the object only with one eye, although they may be said to 
see it with both ; the perception being the combined operation 
of the organ and of the mind. 
If the sensation of one eye be weak, it is very liable to be 
neglected altogether, and that eye is apt to wander from the 
true axis ; and if the person be careless, or given to distort his 
eyes in childishness, a permanent squint may be given to 
the eyes. , 
Another cause of squinting, in children, is the being so laid 
in their cradle, that the light strikes obliquely into one of the 
eyes, whilst the other cannot see it; by which means one of 
the eyes only comes by degrees to be directed to the light, 
whilst the sensation of the other is disregarded. What is very 
extraordinary in squinting, is the correspondence in the mus- 
cles of the eye,* notwithstanding the great distortion of the 
eyeball; for, when both eyes are open, as the sound eye 
turns in all variety of directions to the surrounding objects, 
the other eye still follows it, but preserves its distance, so as 
in a manner to avoid all interference. Blows on the head, 
drinking and smoking, and a variety of irritations, occasion- 84 
OF SEEING IN GENERAL. 
ing convulsions and distortion of the eyes, cause double vision. 
As this is evidently produced by the affection of the mus- 
cles moving the eyeball,* since any change upon the retina 
could not give occasion to such distortions in a state of insen- 
sibility, we may naturally conclude, that squinting is some- 
times the consequence of irregular action of the muscles ; for 
if those transient causes are apt to effect them, so will they be 
apt to be permanently affected.f 
We can distort our eyes by unnatural effort, but we cannot 
squint; that is to say, we can bring our eyes into such a forced 
situation that we cannot see any thing distinctly ; but we can- 
not keep one eye distinctly upon an object, and turn the other 
from it.—Such a position of the eyes, at least, (and which is 
exactly that of those who squint unintentionally,) I cannot, by 
any means, accomplish.j: This Sshows the strict correspon- 
dence betwixt the moving muscles of the eyeballs. By this 
experiment, we shall find the difficulty of that method of cor- 
recting the squint proposed by Ur. Jurin, or of commanding 
motions of the eyes different from those which have been 
bestowed by nature, or acquired by habit. But habit I be- 
lieve to be much more seldom the origin of squinting than is 
generally supposed. It is said, by Dr. Reid and others, that 
we see young people, in their frolics, learn to squint, making 
their eyes either converge or diverge when they will to a very 
considerable degree : why should it be more difficult for a 
squinting person to learn to look straight when he pleases ? 
The reason of the greater difficulty is obvious, that in making 
the eyes converge or diverge the will is acting upon both eyes 
equally; but to distort one eye inward or outward, and at the 
same time to keep the other fixed, is to me like an absolute 
impossibility. Most people, who squint, have a defect in the 
* The command of voluntary muscles is first lost infntoxication ; and, there- 
fore it is more likely that the muscles should lose their natural action and cor- 
respondence than the retina. 
f In Smith’s Optics, there is a case of squinting and double vision occa- 
sioned by a blow. In Buffon’s Dissertation, in the Acad. Roy. des Sc. 1743, 
squinting after long continued pain of the head. I n the Mem. Roy. de 1’Acad. 
des Sc. 1718, Hist. p. 29, there is a curious instance of false vision. 1 find also 
quoted several cases of strabismus from sudden fright, in E/them. Germ. cent. 3. 
& 4. obs. \52. p. 349. lb. dec. 3. an. 8. & 11. ob. 57. d. 114. Ib. dec. 3. an 9 
& 10. obs. 67. “ Novi .luvenem paralysi obnoxium, cui cum caeteris oculi sinis- 
tri musculis relaxatis, adducens fortius contraheretur propter oculum ita dis- 
tortion objectum quodcunque duplex apparebat, nec quod verum esset distin- 
guere potest.” Willis de anima Brut. P. Physiol, p. 77. An instance of the 
loss of corresponding motions of the eyes, and strange illusions of sight. See 
in the Enquiry into the nature of mental derangement by Dr. Crichton, vol. 
i. p. 147- 
+ It is said that astronomers, who are much used to attend only to the im- 
pressions of one eye, are sometimes able to squint at pleasure. See Mr 
Home, Phil. Trans. 1797, p. 17. OF SEEING IN GENERAL. 
85 
distorted eye, a weakness which they do not observe, from 
want of attention to the impressions upon that eye. It will be 
difficult to determine whether this defect be an original fault, 
or the effect of the want of use ; since, by tying up the sound 
eye, the weak one becomes gradually stronger, so that the 
person becomes able to read with it: much be attributed 
to the neglect of impressions. 
It may be observed, that this neglect of the impressions, 
which are actually received, is not at all like that disuse, 
which is the consequence of no impression being received: 
for darkness increases the sensibility of the retina, while this 
dissipates and exhausts it. That squinting is not produced by 
the weakness of the impression received upon the nerve, 
would appear from the circumstance that opacity of the hu- 
mours or the gutta serena do not occasion an alteration of the 
usual correspondence in the muscles moving the eyeballs. 
It is said, that in those who have lost the sight of one eye, 
the habit of directing it to the object they look at is lost, be- 
cause this habit is no longer of use to them.* This I have 
never observed, nor should I think it apt to happen, unless the 
muscles of the eye had been injured from the same cause 
which destroyed the sight; at any rate, it is in a very imper- 
fect degree, and not such as we should call a squint. 
In regard to the cure of squinting, it seems the most rea- 
sonable, in the first place, to endeavour to strengthen the 
weak eye by use, and by tying up the sound one. In this case, 
the distorted eye becomes properly directed to the object, and 
the strength of the impression is in some degree restored. 
When this has been persevered in for some time, and the per- 
son is allowed to look at any object with both eyes, the weak 
eye will perhaps be again distorted from the true axis ; but, 
probably, with a painful effort and double vision, which shows 
some progress in the recurrence of the two eyes, and their 
proper sympathy, and that the impression on the weak eye 
is at least attended to. After this, it will be time enough, by 
Dr. Jurin’s method, to endeavour to correct the squint:— 
u Place the child before you, and let him close the undistorted 
eye, and look at you with the other. When you find the axis 
of this eye fixed directly upon you, bid him endeavour to keep 
it in that situation, and open his other eye. You will now im- 
mediately see the distorted eye turn away from you towards 
his nose, and the axis of the other will be pointed at you. But 
with patience and repeated trials he will, by degrees, be able 
to keep his distorted eye fixed upon you, at least for some lit- 
tle time after the other is opened. And when you have brought 
* Dr. Reid, 86 
OF SEEING IN GENERAL. 
him to continue the axis of both eyes fixed upon you, as you 
stand directly before him, it will be time to change his posture, 
and to set him first a little to one side of you and then to the 
other, and so to practise the same thing ; and when, in all 
these situations, he can perfectly and readily turn the axis of 
both eyes towards you, the cure is effected. An adult person 
may practise all this with a glass, without a director, though 
not so easily as with one. But the older he is the more pa- 
tience is necessary. About twenty years ago, I attempted a 
cure, after this manner, upon a young gentleman about nine 
years of age, with promising hopes of success ; but was inter- 
rupted by his falling ill of the small-pox, of which he died.” 
Dr. Jurin preferred this method to the use of tubes or shells 
with small holes in them, which have been recommended. 
But what appears to me the great difficulty, lies in the strength 
of the impression received upon the sound eye, which causing 
the impression of the weak eye to be entirely neglected, it is 
again thrown out of the line of direct vision. I conceive it, 
therefore, to be a necessary part of the experiment with 
tubes or shells, that the vision through the tube, applied to 
the sound eye, shall be so obscured as to have some accord- 
ance with the lesser sensibility of the weak eye, and then ob- 
jects being seen equally with both eyes, a gradual accordance 
of the muscles may be produced. The conviction of the ne- 
cessity of giving an equality to the strength of the sensation 
of both eyes must have struck M. de Buffon, since he says, in 
his Dissertation in the Academy of Sciences, that a plane 
glass should be applied to the weak eye and a convex one to 
the strong eye, so as to reduce the last to a state less capable 
of acting independently of the other. 
But what is called a weakness, is very frequently, I am con- 
vinced, merely a short-sightedness in one eye : what the effect 
of this should be we may experience if we look to an object 
with both eyes, but with one of them through a concave or 
convex glass; if we are looking upon a book, there will be pro- 
duced a confusion of the letters, but, by a little practice, the 
letters will become again distinct. By an attentive observation, 
we shall find that this is the consequence of attending solely 
to the impression received in the naked eye : nay, what is still 
more strange, we can attend, in this experiment, to the im- 
pression upon the point of the axis of one eye and to the gene- 
ral impression of both. If, while looking upon the letters of 
a large page, I move the convex glass of a small degree of 
power sideway before my right eye, the whole letters of the 
page seem to move, leaving distinct and stationary a circular 
spot containing a word or two. Here, by no effort, while I OF SEEING IN GENERAL. 
87 
took with both eyes, can I lose the steady and distinct sight 
of these few words, because their image is received upon the 
more sensible central point of the retina of my left eye: but 
all the other part of the sphere of vision I can see alternately, 
dimmed or distinct, as I choose to attend to the less powerful 
impression of the right eye, or the natural sensation of the 
left. We see, by this experiment, how easy it is to neglect 
the impression of one eye, if it be no stronger than that of 
the other, (and of course more easily if it be weaker,) and 
how impossible it is to neglect the more vivid impression. 
From such a radical defect in the vision, as the humours of 
one eye having a different focus from the other, and conse- 
quently an indistinctness of vision produced from two images 
of different sizes intermingling their colours, children seem 
very frequently to be made to squint; and I have known adults, 
with a degree of the same inequality in the eyes, kept from 
squinting only by a particular attention to the direction of their 
eyes. M. de Buffon, in his Dissertation already quoted, after 
affirming what has been already delivered, viz. that no one 
squints with both eyes at once, says, he has observed three 
instances in which the eyes, according to circumstances, were 
alternately distorted from the object. This he accounts for by 
finding that, with one eye, the letters of a book could be 
seen at the distance of two or three feet, and not nearer than 
fifteen inches ; while, with the other, the fetters could be dis- 
tinguished at the distance of from four to fifteen inches only. 
Consequently’, when looking to distant objects, the image 
being more distinct with the long-sighted ey-e, the other was 
turned from the object; but when objects at a small distance 
were seen, the image in the far-sighted eye being imperfect, 
it is turned from the axis, that i-t may not interfere with the 
stronger image of the other eye, which is now directed to the 
object. 
A frequent effect of the weakness left by’ long fevers in chil- 
dren, is a squint which gradually goes off as the strength is 
restored. It is observed, also, that squinting and double 
vision are, in some fevers, a concomitant with delirium and 
phrenitis. This symptom proceeds, in all likelihood, from an 
unequal tension of the muscles of the ey’eball. The double 
vision is the effect of discordance in the action of the muscles. 88 
CHAP. XII. 
OF THE EYELIDS, OF THEIR GLANDS, AND OF THE COURSE 
OF THE TEARS. 
Having completed the description of the eye, as the organ 
of vision, we have now to attend to its connections, its adven- 
titious membranes, the glands of the eyelids, and the course 
of the tears. It is plainly necessary that the eye should not 
be loose in the socket; but that, in its rolling motion, it should 
still be attached ; and that, although the delicate anterior sur- 
face must be exposed, the internal parts of the socket should 
be defended from the intrusion of extraneous bodies. This 
is accomplished by the tunica conjunctiva. 
The tunica conjunctiva, or adnata, is the inflection of 
the common skin of the eyelids. It goes a little back into 
the orbit, and is again reflected, so as to come forward and 
cover the forepart of the eyeball. Here it is pellucid, and 
the white coat of the eye shines through it. It covers the 
cornea also ; and here it is perfectly transparent; loses its 
character of vascularity, as the conjunctiva ; and is assimi- 
lated to the nature of the cornea. As this coat is a continua- 
tion of the common integuments, it is, like them, vascular, 
and liable to inflammation. The tunica conjunctiva, is the. 
common seat of ophthalmia. In the commencing inflamma- 
tion, we see the vessels turgid or blood-shot ; by and bye, they 
elongate towards the surface of the cornea ; the patient com- 
plains of dimness ; the dimness becomes apparent to the sur- 
geon ; spots of opacity then form in the cornea ; and the ves- 
sels of the conjunctiva now take a course over the turbid sur- 
face of the cornea. In this stage of the inflammation, by cut- 
ting the turgid vessels of the conjunctiva, we interrupt the 
source of blood for a time, and procure a small evacuation ; 
but these vessels soon coalesce again, and the flow of blood is 
renewed. 
Eyelids.—Birds which mount into the higher and clearer 
regions of the atmosphere have a third eyelid, which is drawn ' 
across the surface of the eye. The eagle, which mounts the 
highest, and the owl, which is most sensible to the impression 
of light, possess this second guard to the eye. The mem- 
brane is drawn across the eye by a particular muscle ; it if 
called membrana nictitans. OF THE EYELIDS. 
89 
The tunica albuginea is the thin tendinous coat formed 
by the insertion of the recti muscles, which expand over the 
anterior part of the eye. I would admit this into the enumera- 
tion of the coats of the eye, merely to prevent confusion of 
names, and to make intelligible the descriptions of some of 
the older writers. It is not properly a coat. Where the con- 
junctiva covers the anterior part of the eye, the white sclerotic 
coat is seen under it; and in consequence of this, the tunica 
conjunctiva is sometimes called albuginea. 
A very material part of the structure of the eye still remains 
to be described; an apparatus by which the surface of the 
eye is preserved from injury, kept moist and perfectly trans- 
parent. 
The eyelids are composed of the common integuments, 
with this difference only, that they have a cartilaginous margin 
to give them shape, and muscular fibres, in the duplicature of 
their membrane, to give them motion. A small semilunar car* 
tilage, which lies like a hoop in their edge, keeps them of a 
regular figure, and so as to close neatly over the eye. This 
cartilage having a triangular edge, and the base of the angle 
forming the flat surface of the margin of the eyelid, they meet 
with the most perfect accuracy. Either end of this hoop-like 
cartilage is connected with the periosteum at the corners of the 
eye, so as to move with its fellow as upon a hinge. This 
cartilage of the eyelid is called tarsus. 
The upper eyelid only, is moved for the admission of light 
to the eye ; it is raised by the levator palpebrse muscle. But 
the eyelids are shut again by the orbicularis palpebrarum, 
which acts on both eyelids, and sometimes with such power, 
as to squeeze the eyeball even to a painful degree. 
The meibomean glands.—These are very elegant little 
glands which lie under the inner membrane of the eyelids. 
About twenty or thirty ducts of these glands open upon the 
tarsus of each eyelid. These ducts run up under the vascular 
membrane of the inside of the eyelids, and minute glandular 
folicules, to the amount of about twenty, are, as it were, attach- 
ed to each of these ducts. These glands exude a white seba- 
ceous matter, which defends the edge of the eyelid from the 
acrid tears, and closes them more accurately by its unctuosity. 
The vascularity of the inner surface of the eyelid is subser- 
vient to these glands ; for the vessels forming their ramifica- 
tions round the little glands, secrete the sebaceous matter into 
them. This, then, is the seat of the ophthalmia tarsi; and 
following this inflammation, the edges of the eyelids, and the 
mouths of the ducts, are sometimes eroded with little ulcers; 
These ducts are the seat of the stye. This is an inflammation. 90 
OF THE SECRETION OF TEARS. 
and closing up of the mouth of one of the ducts, which then 
swells up into a little hard granule in the edge of the eyelid, 
accompanied with inflammation of its cyst or surrounding 
membrane. 
OF TIIE SECRETION AND COURSE OF THE TEARS. 
The lachrymal gland is seated in the upper and outer 
part of the orbit, and behind the superciliary ridge of the fron- 
tal bone. It is of a flattened form, and is depressed into a 
hollow of the bone. Several ducts from this gland open upon 
the inner surface of the upper eyelid. By the reflection of 
the membrana conjunctiva from the eyelid over the surface of 
the eyeball, dust and motes are prevented from getting be- 
hind the eyeball; and when they have got under the eyelids, 
the extreme sensibility of the tunica conjunctiva excites the 
lachrymal gland, and the orbicular muscle of the eyelids, 
(which, by its pressure, accelerates the flow of the tears,) and 
the dust or motes are washed out. The puncture lor re-ab- 
sorbing the tears and conveying them into the nose, being at the 
inner angle or canthus of the eyelids, we see the intention ol 
the ducts of the lachrymal gland opening on the inside of the 
upper eyelid towards the outer angle : for, by this means, the 
tears arc spread over all the surface of the eyeball, by the 
motion of the eyelids, before they decline into the puncta. 
But the tears do not flow only when the gland is excited b) 
motes ; their secretion is perpetual, and, together with the mo- 
tion of the eyelids, they perpetually moisten the surface of the 
eyeball. Even during sleep they flow continually ; and here 
we may admire* a provision for their conveyance towards the 
inner canthus, in the inclination of the tarsus to each other; 
for the eyelids meet only on the outer edge of the broad sur- 
face formed by the tarsus, the consequence of which is, that a 
kind of gutter is formed in the angle by the inner edges of 
the tarsus not meeting, which leads the tears from the ducts 
of the lachrymal gland towards the puncta lachrymalia. 
The puncta lachrymalia are the mouths of two ducts 
which form the beginning of a canal for drawing off the tears 
from the eye into the nose. These puncta are placed at the 
inner canthus of the eye, and on the termination of the tarsus 
of the upper and under eyelid : they are surrounded by a 
rigid substance ; and their patent mouths absorb by capillary 
attraction. They lead the tears into the lachrymal sac, and 
thenCe the tears pass into the nose. 
ThecARUNcuLA lachrymalis is that little granulating-like 
body which lies in the inner angle donned bv the two eyelids. OF THE SECRETION ®F TEARS. 
91 
Very small hairs are seen to sprout from it, and some small 
sebaceous foiicles open upon its surface. Connected with the 
carunculalachrymalis is the membrana or valvula semilu- 
naris. This isavascular membrane which is drawn from under 
the caruncula lachrymalis by the direction of the eye outward, 
so as then to appear like a web spread over the white of the 
eve near the inner canthus. By directing the eye towards the 
nose, this membrane is again accumulated about the carun- 
cula. This, then, is a very particular mechanism, not as is 
generally described, for applying the tears to the. puncta la- 
chrymalia, but for accumulating and throwing out the motes 
and dust from the eye, and for guarding the puncta from the 
absorption of such little particles as might irritate or obstruct 
them. 
In birds, the valvula semilunaris is drawn, by a muscle and 
small tendon inserted into it, quite across the eye, so as to act 
like a third eyelid ; it is in them called membrana nictitans. 
The lachrymal sac and duct lie in the os unguis or la- 
chrymale. The sacculus is a bag of an oblong or oval figure; 
it is sunk into the fossa of the os unguis, and defended by the 
frontal .process of the superior maxillafy bone ; and it is 
covered by the ligamentous connection of the orbicularis mus- 
cle. This sac is the dilated upper end of the nasal duct; and 
into it the two canaliculi lachrymales (the extremities of which 
are the puncta,) open as distinct tubes.* 
Two coats are described as covering the lachrymal sac ; a 
nervous, white, external coat; and avascular, pulpy,pituitary 
membrane. This sac, diminishing towards the lower part, and 
being received into the complete canal of the bone, becomes 
the nasal duct. Taking a course downward and backward, it 
opens into the nose under the inferior spongy bone. The la- 
chrymal sac and duct are by some conceived to be muscular, 
so as to enable them to convey the tears into the nose ; or it 
may be conceived, that they act like a syphon, the duct reach- 
ing down into the nose acting like the long leg of the syphon, 
and drawing the tears in at the openings of the puncta. Birds 
have a copious secretion of tears, which is necessary to them, 
from the rapid course through the air elevating the evapora- 
tion of the tears. 
Fishes have no lachrymal gland : the fluid they swim in ren- 
ders this secretion unnecessary. But I think it would appear, 
that the connections of the orbicularis muscle over the sac is of 
a nature to accelerate the passage of the tears, and even per- 
fectly to compress the sac. The lachrymal sac and duct are 
* Dr, Monro 92 
OF THE SECRET I OH OF TEARS. 
very frequently diseased and obstructed. For example, after 
small-pox, syphilis, or in scrofulous constitutions, the inner 
membrane of the sac being of the nature of the pituitary mem- 
brane of the nose, inflames, swells, and adheres. The conse- 
quences of this are, first, a swelling of the lachrymal sac in 
the inner angle of the eye, and a watery or weeping eye ; upon 
pressing the tumour, the tears, mixed with mucus, are forced 
back through the puncta; by and bye the sac imflames and 
suppurates; matter is discharged by pressure of the sac: and, 
lastly, it is eroded and burst out, discharging the tears and 
matter on the cheek. This is the complete character of the 
fistula lachrymalis. While the sac bursts outwardly, it often 
does further mischief within, by making carious the thin 
lamina of bone in which it lies. The theory of the ancients, 
with regard to this disease, was that the disease was proceed- 
ing from the caries of the os unguis, and they perforated with 
the actual cautery, until the patients smelt it in the nose! as 
much with the intention of remedying the caries as to give 
passage to the tears. But it is not the bone which is the ob- 
struction to the perfect cure of this disease by operation, but 
the membranes, which close again after the most ingenious 
attempts to preserve the passage. The vis medicatrix, in this 
instance, seems not to be so well aware of her interest as some 
physiologists would inculcate. She is, here, ever at variance 
with the artifice of the surgeon. BOOK II. 
OF THE EAR. 
CHAP. I. 
OF THE SOUND, AND OF THE EAR IN GENERAL. 
THE ear is that organ by which we are made susceptible of, 
the impression of sound. 
Sound is the effect of impression on the auditory nerve, by 
which corresponding change is produced in the brain ; or we 
say sound is a vibratory motion of bodies depending upon their 
elasticity or tension. It may be produced by the vibration 
and motion of the air, but not without the intervention of 
solids. The human voice, for example, does not depend 
merely on the percussion of the air, but on that vibration, as 
combined with the tension and consequent vibration of the 
glottis, excited by the current of air ; which, again, is modi- 
fied by the mouth. The science of sound as producing me- 
lody and harmony is a very interesting and curious one, for by 
the succession of sounds or notes, and their consonance, there 
is a language for which words are no substitute. 
There is no body impervious to sound, or, in other words, 
incapable of transmitting the vibration. That sound is com- 
municated through the medium of the air,, we know from the 
circumstance, that a bell, when struck in a vacuum, gives out 
no sound: and again, from this, that the condensed state of 
the atmosphere affords an easier communication of sound, 
and conveys it to a greater distance. The velocity of the im- 
pression transmitted by the common air is computed at 1130 
feet in a second ; and sound, when obstructed in its direct 
motion, is reflected with a velocity equal to that with which 
it strikes the solid body by which its progress is interrupted. 
That water conveys the vibrations producing sound, has 
been proved by experiment. It was once the saying of natu- 94 
or sound. 
ralists, that to suppose fishes to have the organ of hearing, 
would be to conceive that an organ were bestowed upon them 
without a possibility of its being of use. But we are assured of 
the fact, that, on the tinkling of a bell, fishes come to be fed ;* 
and it was the custom for the fishermen on the coast of Brit- 
tany, to force the fish into their nets by the beating of drums,f 
as our islanders are at present accustomed to do when the 
larger fish get entangled amongst the rocks. We are told, that 
in China, they use a gong for the same purpose. These facts 
were once of importance, though more accurate observation 
has now made them superfluous. The Abbe Nollet took much 
pains to decide the question, whether water was a medium for 
sound. After considerable preparation, and acquiring a dex- 
terous management of himself in the water, (for which he 
takes great merit to himself,) he found that he could hear un- 
der water the sound of the human voice, and even distinguish 
conversation and music. The human ear being an organ im- 
perfectly adapted to this medium of sound, these experiments 
do not inform us of the relative powers of air and water in the 
transmission of sound. But another experiment of the Abbe 
Nollet proves, what indeed to me is sufficiently evident, from 
the structure of the ear of fishes, viz. that the water transmits 
a much stronger vibration than the air. When he sunk under 
water and struck together two stones which he held in his hands, 
it gave a shock to his ear which was insupportable, and which 
was felt on all the surface of his body, like that sensation 
which is produced when a solid body held in the teeth is 
struck by another solid body4 He observed in other expe- 
riments, that the more sonorous the bodies struck were, the 
less vivid was the impression; by wrhich it would appear, that 
water, though it conveys an impression more strongly to the 
ear, than the air, is not equally adapted to the resonance and 
variety of tone. Indeed, this is a natural consequence of the 
water, a fluid of greater density being in close contact with 
the.sounding body, and suppressing its vibration. In these 
* Boyle. 
■j- M. l’Abbe Nollet, Acad. R. des Sciences. Naturalists were very in- 
credulous of the.effect said to be produced by music on lobsters. Some may 
be so still; but we may trust the following' observation of Minasius, in his Dis- 
sertation. “ Su de timpanetli dell udito scoperti ncl Granchio Paguro” “Pro- 
“ priis observationibus certior factus asserit obscura nocte, placidoque mart 
“ quoties piscatores ardentibus saculis paguri in littore hxrentis oculos lucis 
“fulgore perstringunt, ut stupido, et pene prrcstigiato animale potiaiitur, fi 
“ forte rumor aliquis ingruit. Caxcrum illico se e littore subducere recipe. 
“ reque intra undas.” See Scarpa Disqinsitiones Anatomica: de Auditu in Iij- 
“ sectis, &c. 
t- These experiments were repeated by Dr. Monro, See his Book of Fishes. 95 
OF SOUXB. 
facts we shall find the explanation of some peculiarities in the 
structure of the ears of fishes. 
Thus, we see, that the vibration of a solid body is conti- 
nued through the air, and through water, until reaching the 
organ of hearing, it produces the sensation of sound. 
Sound, it will be evident, is also communicated, through so- 
lids. When we put the ear to one end of a log of wood of 
thirty feet in length, and strike upon the other, we are sensible 
of the impression ; and when a solid body applied to the bones 
of the head, or to the teeth, is struck, we are sensible of the 
noise and this is felt even by those who are deaf to impres- 
sions conveyed through the air: indeed it is part in this way 
that we are to judge whether deafness may be cured by ope- 
ration, as depending upon some injury of the mechanism of 
the organ, or whether it be an incurable affection of the nerve, 
or brain itself. If the sound be perceptible when conveyed 
through the teeth, or when a watch, for example, is pressed 
upon the bone behind the outer ear, we are assured that the 
internal organ is unaffected; and upon inquiring farther into 
the case, we may find that the deafness proceeds from some 
disease of the outer tube of the ear, or of that tube which 
leads into the throat, and that it can be remedied. 
CHAP. II., 
GENERAL VIEW OF THE VARIETIES IN TOE EAR.S OF ANIMALS.f 
There is in the scale of animals a regular gradation in the 
perfection of the organ of hearing. But, in the human ear, 
we find united all the variety of apparatus for communicat- 
ing the vibration to the internal organ, and along, with this 
the most extensive distribution of nerves in the labyrinth, or 
inmost division of the ear, to receive that impression. 
The ultimate cause of this more complex structure is the 
greater power with which man is endowed of receiving through 
the ear, various impressions of simple sounds : language, mu- 
sic, and various modifications of the sense, of which the lower 
animals are probably incapable. 
* Perhaps we cannot call this sound. 
fin the following short account of the comparative anatomy of the ear, ah 
though I have taken every assistance in my power from books, I have de- 
scribed the structure, in all the examples, from my own dissections and oh 
serration. 96 
or THE EARS OJ ANIMALS. 
As in treating of the anatomy of the eye, we do not attempt 
to investigate the manner in which light acts upon the retina, 
in producing the sensation of colours, but endeavour merely to 
explain the structure of the eye ; to show how the coats sup- 
port and nourish the humours ; how the humours are subser- 
vient to the concentration of the rays of light, and assist their 
impulse upon the retina : so, in the same manner, in explaining 
the structure of the ear, we need not investigate the philosophy 
of sound, nor the nature of those impressions which are made 
by it on the sensorium through the nerves ; our views are 
limited to the structure of the ear—we have to observe the 
mechanism by which the strength of vibrations is increased and 
conveyed inward to the seat of the sense, and the manner in 
which the nerve is expanded to receive so delicate an im- 
pression. 
The method of studying this subject, which is at once the 
most instructive and the most amusing, is to trace the various 
gradations in the perfection of the organ, through the several 
classes of animals. It is chiefly comparing the structure 
of the viscera, and the organs of sense in animals and in man, 
that comparative anatomy is useful in elucidating the animal 
economy. For example, in the stigmata and air-vessels Of 
insects and worms ; in the gills of fishes ; in the simple cellular 
structure of the lungs of amphibise ; in the more complicated 
structure of the lungs of birds; we observe one essential requi- 
site, through the whole gradation, viz. the exposure of the cir- 
culating fluids to the action of the air. And in this variety of 
confirmation, we see the same effect so modified as to corre- 
spond with thp habits and necessities of the several classes of 
animals. In the same manner, with regard to the circulating 
system, we are taught the explanation of the double heart in 
the human body, by tracing the variety of structure through the 
several classes of animals ; from the single tube circulating 
the fluids of insects, the simple ventricle of fishes and rep- 
tiles, the double auricle and perforated ventricle of amphibia, 
up to the perfect heart of the warm-blooded animal. The 
organs of generation, and the economy of the foetus in utero, 
is, in the same degree, capable of illustration from compai'ative 
anatomy. But most especially, in the structure of the ear, is 
there much scope for this kind of investigation. We find such 
varieties in the ear of reptiles, fishes, birds, and quadrupeds, 
as lead us, by gradual steps, from the simpler to the more 
complex structure. 
The simplest form of the organ of hearing is that in which 
we find a little sac of fluid, and on the inside of the sac the pulp 
of a nerve expanded. If an animal having such an organ. OF THE EARS OF ANIMALS. 
97 
breathe the air, a membrane closes this sacculus on the fore- 
part ; and, by means of this membrane, the vibrations of the 
air are communicated to the expansion of the nerve through 
the fluid of the sac. But if the animal inhabits the water only, 
it has no such membrane to receive the impression; the organ 
is incased in bone or cartilage, and instead of the membrane, 
some small bone or hard concreted matter is found in contact 
with the pulp of the nerve. The sound, passing through the 
waters, is, in such case, conveyed to the organ, not by any par- 
ticular opening, but through the bones of the head ; and this 
concrete substance, partaking of the tremulous motion, com- 
municates the sensation to the nerve.* 
For example, in the crab and lobster, we find a prominent 
bony papilla or shell, which is perforated, with a membrane ex- 
tended across the perforation, and behind this membrane there 
is a fluid, in which the nerve is expanded, and which receives 
the impulse conveyed to the membrane. In the cuttle-fish, 
again, there is no external opening ; there is merely a little 
sac under the thick integuments ; this sac has in it a small 
concretion or bone for receiving the vibration ; which, in this 
animal, is conveyed by a more general impression upon the 
head than in those last mentioned ; and the vibration of this 
loosely poised bone or concrete seems equal to the provision 
of the membrane which, in the crab, closes up the external 
opening in the perforated shell. 
In fishes, there is a considerable variety of structure. 
Those which remain perpetually under water, have not the 
outer membrane, nor any apparatus for strengthening the first- 
received undulations of sound. But such as lie basking on the 
surface of the water, and breathe through lungs, have an exter- 
nal opening—a car.al leading to the membrane, and behind 
the membrane bones to convey the vibration to the internal 
parts, and these internal parts, the seat of the sense, are actu- 
ally as perfect asin terrestrial animals. 
In neither of the species of fishes, the cartilaginous nor spi- 
nous fishes, is there a proper external opening, as in animals 
breathing air. They receive the impulse from the water, upon 
the integuments and bones of the head ; but within the head, 
and in the seat of the sense, they have a most beautiful appara- 
tus for receiving and conveying those general vibrations to the 
expanded nerve. There is in every ear, adapted to hearing 
under water, a bone or concretion, placed so as to vaccilate 
*It is conceived by some that the antenna of insects conveys to them the; 
vibration of bodies, and that they may be considered as an imperfect variety 
of this organ. 98 
OF THE EARS OF ANIMALS. 
easily, and which is destined to agitate the fluid in which it is 
suspended with a stronger vibration than could be produced 
merely by a general impulse. Besides this provision in fishes, 
there is a very elegant structure for still further increasing the 
surface destined to receive the impulse, and for exposing to 
that impulse or vibration a larger proportion of the expanded 
nerve. It consists of three semicircular tubes, which penetrate 
widely within the bones of the head. They are filled with a 
fluid, and have in their extremities a division of the nerve which 
is moved or otherwise affected by the vibration of the fluids 
contained within the tubes. 
There is a slight variety, however, in the ear of cartilaginous 
fishes. In the head of the skate, for example, there is under 
the skin, at the back of the head, a membrane extended across 
a pretty regular opening. This, however, is not considered as 
the opening of the ear; but a passage, like a mucous duct, 
which is beside it, has given occasion to a controversy between 
Professors Scarpa and Monro ; and it may not be out of place 
to inquire into this disputed point, 
We have seen that water conveys the sound of vibrating 
bodies with a shock almost intolerable to the ear, and with a 
particular and distinct sensation over the whole body. We 
see, also, that, in the greater number of fishes, there is con- 
fessedly no external opening, the whole organ is placed under 
the squamous bones of the head. Yet the cartilaginous fishes 
which are supposed to have an external ear, swim in the same 
element, and are in no essential point peculiar in their habits. 
And we should receive with caution the account of any pecu- 
liarity in the organ of hearing of one class of fishes, which is 
not common to all inhabiting the same fluid. Such animals 
as occasionally pass from the water into the air, must have a 
membrane capable of vibrating in the air; but even in them, 
it is expanded under the common integuments, and protected 
by them. Were it otherwise, when the creature plunged into 
the water, it would be assailed with that noise (confounding all 
regular sounds,) of which man is sensible when he plunges un- 
der water. It appears opposite to the general law of nature, to 
suppose any species of fish having that simple and more deli- 
cate membrane which is evidently intended to convey atmos- 
pheric sounds only, while, on the other hand, creatures living 
in the water alone, should have an organization fit to endure 
the stronger vibration of their denser fluid, and Which would 
be useless and absurd in those existing in our atmosphere. 
When we come to examine the ear of the skate, we find, 
that what Dr. Monro conceives to be the outward ear of the OF THE EARS OF ANIMALS. 
99 
fish,* is really, as represented by Dr. Scarpa, a mucous duct 
merely ;f which does not lead into the sacculi of the vestibule 
and semicircular canals, as appeared to Dr. Monro, and that 
to suppose this would be to acknowledge the free access of 
air and water to the immediate seat of the organ, and to the 
soft pulp of the auditory nerve, a thing absurd in every view, 
impossible in nature, and very wide of the truth.:(: To me it 
appears, that this narrow duct cannot be considered as the 
external ear ; because we find in the skate a proper membrane 
under the thin integuments, quite unconnected with the duct, 
for transmitting the sound; and, upon following this mucous 
duct, we find it taking a circuitous course, and filled with a 
strong gelatinous matter; it is every where narrow, and filled 
with a glutinous secretion. It has no membrane stretched 
across it, and bears no resemblance to the external ear of anv 
other animal. 
We may conclude, then, that fishes have no external open- 
ing like terrestrial animals ; that, instead of this outward pro- 
vision, they have the moveable bone within the organ. Al- 
though the cartilaginous fishes have a membrane extended 
over part of the organ, which, in the spinous fishes is com- 
pletely surrounded with bone, it is not to be considered as 
capable of the tremulous motions of the membrana tympani 
of terrestrial animals, but may be considered as analogous 
to the membrana fenestrse ovalis : and, since it lies deep un- 
der the integuments, we have no reason to believe that sound 
is transmitted to the organ of hearing in fishes, any otherwise 
than through the general vibration of the head. 
The organ of hearing in amphibious animals, demonstrates 
to us a difference in the manner in which the sensation is re- 
ceived ; for they have both the outer membrane to receive the 
vibration of the air, and a mechanism of small bone to convey 
this motion into the seat of the sense ; and they have, besides, 
within the ear itself, a chalky concretion ; a provision plainly 
* “In the upper and back part of the head of a skate, and in a large fish 
“ weighing 150 pounds, at the distance nearly of one inch from the articula- 
“ tion of the head with the first vertebra of the neck or atlas, two orifices, 
“ capable of admitting small sized stocking wires at the distance of about an 
“ inch and a quarter from each other, surrounded with a firm membranous 
“ ring, may be observed. These are the beginnings of the Meatus Auditorii 
“ Externi.” Treatise on the Ear, p. 208. 
f Dr. Scarpa,-speaking of this opinion of Dr. Monro, says, “ qua in re vehe- 
“ menter sibi hallucinatus est, ostia nimirum ductuum mucosorum, ut manifes- 
“ turn est, pro auris meatubus accipiens. Etenim omnino nullum est in car- 
“ tiligineis piscibus ostium auditus extus adapertum, membranaque fenestra 
“ ovalis sub communi integumento recondita jacet et cooperta.” 
+ “ Quod et absurdum est et a rei veritate quam maxime alienum.” Vid. 
Anatomicx IHsqmsitisnes de aiuKtu et olfacln, auctore A. Scarpa. 100 
or THE EARS OF ANIMALS. 
intended for propagating the motion communicated through 
the water. 
In serpents, birds, and quadrupeds, we shall hereafter trace 
the various gi-adations in the perfection of this organ. We 
shall find, that, as the animal rises in the scale, the cavities 
and tubes of the ear are extended and varied in their form. 
Now, I conceive that, while the multiplied forms of the tubes 
and sphericles of the internal ear afford a more expanded and 
susceptible surface for receiving impressions, the consonant 
forms of the parts enable them to receive a stronger vibration, 
and a more perfect and modified sound. 
A cord of a musical instrument will vibrate when another in 
exact unison with it is struck. The vibration communicated 
to the air is such as is adapted to the tension of the sympho- 
nic cord ; and no other percussion of the air, however violent, 
will cause it to sound. Again, the air passing through a tube 
of certain dimensions, will not communicate to it a motion, 
nor call forth its sound, while the air, passing in equal quan- 
tity through a tube of one degree of difference, will rise into 
a full note. What holds true in regard to the unison of cords, 
is also true of cylinders, or even of the walls of a passage or 
room, a certain note will cause the resonance of the passage 
or room, as a certain vibration will call forth the sound of the 
tube of an organ ; because it is, in all these instances, neces- 
sary that the impulse be adapted to the position of the surfaces 
and their powers of reverberation. 
These few facts illustrate what I mean, by saying, that the 
various forms of the internal ear of animals, as they advance 
in the scale, give additional powers to their organ. In the 
first example of the simple ear, where a bone vibrates on the 
expanded nerve, I should conceive that the sensations were in 
consequence of this simple percussion capable of little variety; 
but in animals where, besides this simpler mechanism there 
are semicircular canals, and more especially in those animals, 
which have still a further complication of the forms of the ear, 
certain sounds will be peculiarly felt in each of these several 
cavities and convolutions; and while the sensation is becoming 
more distinct, by the perfection of the organ, it admits, also, 
of a greater variety of sounds or notes : so that a certain state 
of vibration will affect the semicircular canals, (one or all of 
them,) and produce the sensation of sound, which would not at 
all affect the vibration of the simple lapillae lying in their sac. 101 
CHAP. III. 
DESCRIPTION OF THE ORGAN OF HEARING IN PARTICULAR 
ANIMALS. 
IN THE LOBSTER AND CRAB. 
In these animals, the structure of the ear is very simple ; but 
it appears to me that Professor Scarpa, in his description, has 
imagined the organ to be more simple than it is in nature. 
In the lobster, there projects from near the root of the 
great antenna, an osseous papilla of a peculiarly hard and 
friable nature. In the point of this papilla we observe a fora- 
men, and a membrane stretched over it. This is the seat of 
the organ of hearing. It is described as containing a sac of 
a pellucid fluid, which adheres to the membrane, while the 
auditory nerve is expanded upon the lower surface of the sac. 
Now,the lobster, being an animal which can live on land as well 
as in water, Scarpa gives this as an instance of a structure cal- 
culated to receive the sensation of sound equally well from the 
water or from the atmosphere. But, from the figure I have 
given of the ear of this creature, it will not appear to be so 
exceedingly simple; while there is evidently a provision for the 
reception of the vibration communicated through the water, 
though it does not indeed strictly resemble that which is com- 
monly found in the ears of fishes. There is suspended behind 
the sacculus, and in contact with the nerve, a small triangular 
bone, which when pulled away,* is found to hinge upon a deli- 
cate cartilage. This bone seems evidently intended, by its 
being thus suspended in the neighbourhood of the pulp of 
the auditory NERVE* for impressing upon that nerve the 
vibration from the water. The lobster, then, has, like the am- 
phibious animals, a double provision for receiving the commu- 
nication of sound alternately from the water or from the air.f 
The ear of the crab differs from that of the lobster in this, 
that, under the projection, there is a moveable case of bone, 
to which we see a small antenna attached. Within this is the 
organ of hearing ; and there is here an internal provision for 
* See fig. 2. 
f From the mucous-like transparency of the nerve in the lobster, it is diffi - 
cult to ascertain its exact relation to this bone. 102 
OF THE ORGAN OF HEARING. 
the transmission of sound to the auditory nerve, which consists 
simply in a few circumgyrations of a pellucid and flexible car- 
tilage : an inspissated fluid surrounds this gyrous cartilage, 
while the pale auditory nerve is expanded behind it. 
Of the ear of fishes.—In the heads of fishes there is a 
cavity separated by a thin vascular membrane from that which 
contains the brain. Within this cavity there is a sacculus dis- 
tended with a fluid, and containing a small bone ;* on the in- 
side of this bag, (which is called the sacculus lapillorum,) a 
great proportion of the auditory nerve is expanded. In the 
cartilaginous fibres, there are three lapillif contained in their 
proper capsules, and surrounded with a gelatinous matter,:}: each 
of the lapilli having its appropriated division of the acaustic or 
auditory nerve distributed upon it in a beautiful net-work. 
This cavity in the head of fishes, resembles the centre of the 
labyrinth in the human ear, and is called the vestibule. With- 
in the vestibule there is a limpid fluid, intersected every where 
by a delicate and transparent cellular membrane ; and the parts 
within the vestibule are supported in their place by this tissue, 
which is similar to that which supports the brain in fishes. 
Besides this central part of the organ in fishes, there are de- 
parting from the vestibule three semicircular cartilaginous 
canals,§ within which, are extended membrarious canals. 
These membranous tubes contain a fluid distinct from that 
contained in the common cavity of the vestibule, nor have they 
any communication with the sacculi, which contain the lapilli, 
although they are connected with them.|| These cartilaginous 
canals are of a cylindrical form, and being as transparent as 
the fluid with which they are surrounded, are not readily dis- 
tinguished in dissection. Each of the cartilaginous canals is 
dilated at one of its extremities into a little belly, which is 
called the ampulla. 
The auditory nerve in cartilaginous fishes*}] is first divided into 
two fasciculi, which are again subdivided into lesser nerves. 
These go to the three sacculi lapillorum, and to the ampullulae 
of the semicircular canals. Before the division of the nerve 
peculiar to the sacculus pierces it, and is finally distributed, it 
* See plate, fig. 3. 
f In many of the spinous and squamous fishes there is only one. In cartila- 
ginous fishes these bodies are not like bone, but like soft chalk. In the 
spinous fishes, on the other hand, they are of the shape of the head of a spear, 
and hard like stone. 
t The gelatinous matter is rather before the bones, and distending the little 
sacculi. 
§ See plate 7. fig. 3. and fig. 4. n d d. 
H So Professor Scarpa asserts, in contradiction to others. 
1 The fifth pair of nerves in fish answers to the seventh in man : has the 
same division into theportio mollis and dura. OF THE ORGAN OF HEARING. 
103 
forms a singular and intricate net-work of filaments. The 
branches to the ampullulae are raised on a partition which is 
opposed to the mouth of the cylindrical part of the tube. 
In the spinous fishes, the three semicircular canals unite in 
a common belly; but in cartilaginous fishes, the posterior 
semicircular canal is distant from the others. 
In fishes, all the parts of the ear are filled with a matter of 
a gelatinous consistence, or viscid fluidity ; and the whole sac- 
culi and semicircular canals are surrounded with fluid. That 
jelly is the most susceptible ol vibration, is evident when we 
fill a glass, and allow a body to fall into it; for then the deli- 
cate vibration is communicated to the finger on the outside of 
the glass ; or by striking the glass, we may observe the tremu- 
lous motion of the jelly. The semicircular canals, it is evi- 
dent, are well adapted to receive the extensive vibrations com- 
municated through the bones of the head, and to convey them 
inward to the nerve expanded in the ampulla. 
From the simpler to the more perfect aquatic animals, we 
may trace several links of the chain by which nature advances 
towards the perfect structure of the ear. We return now to 
observe, in the first example of terrestrial animals, the most 
simple state of that part of the organ which receives the sen- 
sation ; but where the structure of the receiving organ is the 
most simple, the mechanism for receiving the vibration and 
conveying it to the internal ear is modified and adapted to the 
atmosphere. 
OF THE EAR IN REPTILES AND AMPHIBIOUS ANIMALS^ 
In reptiles, which form the intermediate class of animals 
betwixt fishes and quadrupeds, the ear has also an intermediate 
structure ; in some individuals of this class the ear resembles 
that of fishes, such as we have described; w'hile, in others, it 
resembles more nearly the common structure of terrestrial 
animals. 
In the salamandra aquatica, a variety of the lizard, there is a 
foramen ovale,* deep under the integuments. In this foramen 
there is a cartilage, in immediate contact with which there is 
a common sacculus lying in the cavity or vestibule ; and in 
this little sac there is found a cretaceous matter; there are 
here, also, semicircular canals, with ampullulte, and a common 
* This is the appropriated appellation of the opening which leads from the 
outer cavity of the ear, or tympanum, into the seat of the proper organ where 
the nerve is expanded. 104 
OF THE ORGAN OF HEARING. 
belly connecting them. In this animal, then, it is evident, the 
ear is similar in structure to that of the cartilaginous fishes.* 
In the frog, the outward apparatus is different, but the in- 
ternal ear is simple.f Under the skin of the side of the head, 
a little behind the prominent eye, we find a large circular 
opening, which tends inward in a funnel-like form: and from 
the upper part of the circle of this meatus we find a small elas- 
tic bone or cartilage suspended. This bone is in contact 
with the common integuments of the head, which are stretched 
over the little cavity. This first bone is placed at a right angle 
with a second bone, and both are lodged in a proper tympanum 4 
This second bone swells out towards its inner extremity, apd is 
accurately applied to the foramen ovale. The foramen ovale 
opens into a cavity which we must call the vestibule, and which, 
in this creature, is peculiarly large in proportion to its size. 
This vestibule contains a sac, upon which the nerve is expanded ; 
it contains also a chalky soft concretion, which is of a beauti- ■ 
ful whiteness, and of a regular figure when first seen, but has 
no solidity.§ The vestibule here, as in all other animals, be- 
ing the immediate seat of the sense, is filled with fluid. 
In serpents, the mechanism external to the seat of the or- 
gan is less complete than in the frog. From the scales behind 
the articulation of the bone which keeps the lower jaw ex- 
tended, a little column|| of bone stretches inward and forward. 
This bone has its inner extremity enlarged to an oval figure, 
and is inserted into the foramen ovale. This creature has no 
membrana tympani, nor does it appear to have so good a sub- 
stitute as the frog: the outer extremity of the bone seems ra- 
ther attached to the lower jaw by a cartilaginous appendage 
and small ligament.Within the skull, serpents have the 
little sac, with the cretaceous matter and semicircular canals, 
united by a common belly.** 
In the turtle, we find a proper tympanum, and by lifting 
the scaly integuments from the side of the head a little above 
the articulation of the lower jaw, we open this cavity. 
* It is said by naturalists, that the salamander never has been heard to utter 
a cry; and as dumbness is in general coupled with deafness, it is natural to 
suppose it has no ears. This is to consider the organ as subservient to conver- 
sation ! 
f See plate, fig. 5 and 6. 
t This tympanum being a cavity containing air, has communication with the 
mouth by a tube, which we shall afterwards find called eustachian tube. Se- 
veral have erroneously described this animal as receiving sounds through the 
mouth. 
§ See fig. 6. d. 
|| Plate, fig. 7. b. 
t See Sgarpa, tab. v. fig. is. 
** Serpents are affected by music; and they will raise and twist themselves 
with every variety of lively motion to the pipe and tabor. OF THE ORGAN OF HEARING. 
105 
Through this cavity there extends a very long and slender 
bone, which, upon the outer extremity, is attached by a little 
elastic brush of fibres to the cartilaginous plate under the in- 
teguments, while the inner extremity is enlarged, so as to ap- 
ply accurately to the foramen, which opens in the vestibule; 
and a passage also opens from the cavity of the tympanum into 
the fauces. In this animal, as in all which we have classed 
under the present division, the internal ear consists of a cen- 
tral cavity, or vestibule, which contains a sac with fluid, and 
cretaceous matter, and of three semicircular canals connected 
by a common belly. This common belly of the semicircular 
canals has no communication tvith the sacculus vestibuli, which 
contains the cretaceous matter, further than as it lies in con- 
tact with it, and as they both lie surrounded by a fluid ; they 
equally receive the impression of the little bony column, the 
extremity of which vibrates in the foramen ovale. 
There being enumerated forty or more varieties of the 
lacerta or lizard, many of these have very different habits. 
Some of them never pass into the water, but inhabit dry and 
dusty places. The lacerta agilis, or common green lizard, 
which is a native both of Europe and India, is nimble, and 
basks, during the hot weather, on the trunks of old trees and 
on dry banks ; but on hearing a noise it retreats quickly to its 
hole. It has the skin over the tympanum extremely thin, and 
such as to answer precisely the office of the membrane of the 
tympanum. So all the varieties of reptiles which, in their 
habits and delicacy of hearing, resemble terrestrial animals, 
have either the membrane of the tympanum, or a skin so deli- 
cate as to produce the same effect; while those which inhabit 
the water have a rough integument, or a hard scale, drawn 
over the tympanum. • Besides this, some have a small muscle 
attached to the bone, which runs across the tympanum; it is 
like the tensor tympani, and is another step towards the pro- 
per structure of the terrestrial ear. 
OP THE EAR IN BIRDS. 
Comparing the internal ear of birds with that of those ani- 
mals which we have already described, we find a very import- 
ant addition. We find here the internal ear (or labyrinth, as 
we may now call it,) consisting of three divisions : the vesti- 
bule, or middle cavity; the semicircular canals; and the 
cochlea ; which last is an additional part, and one which we 
have not in the class of animals already described. Leading 106 
OF THE ORGAN OF HEARING. 
into these three cavities, there are two foramina; the fenes- 
tra rotunda, and the fenestra ovalis ; and both these 
openings have a membrane stretched over them in the fresh 
state of the parts. The first, the fenestra ovalis, or foramen 
ovale, receives the ossiculus auditus, which is in birds like 
that which we have already described in reptiles.* This ossi- 
culus connects the membrana tympani (which is here of a regu- 
lar form) with the vestibule, and conveys the vibration of the 
atmosphere to it. 
The semicircular canals are here also three in number, and 
are distinguished by the terms minor, major, and maximus ; 
but as the major and minor coalesce at one of their extremi- 
ties, and enter the vestibule together, the semicircular canals 
open into the vestibule by only five foramina in place of six. 
Each of the semicircular canals is dilated at one extremity 
into an elliptical form, while the other extremity is of the na- 
tural size of the diameter of the tube. These canals are 
formed of the hard shell of bone, and are surrounded with 
bone, having wider and more open cancelli. 
In the dry state of the parts, we find a cord passing through 
the semicircular canals, which some have called the zonul.e 
nervosi. But these are the membranous canals, which are 
contained within the bony ones, dried and shrunk up. Within 
the bony cavities of the labvrinth, there is laid a pellucid 
membrane which contains a fluid, has the nerves expanded 
upon it, and is the true vestibule and semicircular canals; 
while the bony case, which we have described, is merely the 
mould of these and the support of their delicate texture.f 
The cochlea, one of the three divisions of the labyrinth, 
is but imperfect in birds, when compared with that part of the 
organ in quadrupeds and in man. The cochlea in birds con- 
sists merely of two cylinders, formed of cartilage, which are 
united toward their further extremity. While the opposite ex- 
tremities diverge, and while one of these cylinders opens into 
* Mr. Home, in his lecture on the muscularity of the membrana tympani, 
(vicl. Phil. Trans. A. 1S00,) says, in birds this membrane has no tensor muscle 
to vary its adjustments, but is always kept tense by the pressure of the end ot 
the slender bone. This is a very imperfect account of the mechanism of the 
tympanum in birds. Therearetwo bones, or one small bone with a cartilage, 
which lies along the membrana tympani. This elastic cartilage has two little 
tendons attached to it. Even the slender bone which stretches from the car- 
tilage to the foramen ovale, the inner extremity of which is enlarged to fill up 
that hole, seems to have a small tendon inserted into it; but whether this be a 
muscular or ligamentous connection. I am unable at present to say. 
t * lately, by accident, drew out the saceulus vestibuli and semicircular ca- 
nals from the bony part of the ear of a bird, and I found the membranous semi - 
circular canal to consist apparently of the same pellucid elastic matter with 
those of fishes. of the human ear. 
107 
the vestibule, the other opens outward into the cavity of the 
tyn panum.* 
' That which more than any other circumstance distinguishes 
the organ of birds from that of animals inhabiting the waters, 
is the want of the bone or stony concretion in the sacculus 
vestibuli. 
CHAP. IV. 
OF THE HUMAN EAR. 
The anatomy of the human ear will naturally be considered 
under three heads: the external ear; the tympanum ; and the 
labyrinth. The outward ear requires no definition. From 
the outward ear there is a cartilaginous tube, which leads into 
the tympanum. The tympanum is the cavity within which 
is placed that mechanism of bones and muscles which increases 
the strength of the vibration, and conveys it inwards to the 
labyrinth. The labyrinth is the general name of those in- 
tricate canals which contain the expanded nerve, and the im- 
mediate seat of the organ. 
SECTION I, 
OF THE EXTERNAL EAR. 
The external ear is formed of an elastic cartilage, cover- 
ed with very thin integuments. The apparently irregular sur- 
faces of the outer ear will be found, upon examination, to be 
so formed that the sinuosities lead gradually into each other, 
and finally terminate in the concha or immediate opening of 
* We find Mr. Ilome saying that the cochlea is neither absolutely neces- 
sary to fit the organ to be impressed by sounds communicated through the air, 
nor to render it what is termed a musical ear; and that this is sufficiently 
proved bythat part being wanting in birds, whose organ is particularly adapted 
to inarticulate sounds. That the cochlea is not necessary to the communica- 
tion of sound through the atmosphere, we have seen from the examination of 
the ear of the reptiles. But since we see that it forms part of the labyrinth in 
birds, we may be led to doubt Mr. Home’s conclusion. 108 
OF THE HUMAN EAR. 
the tube of the ear. By the constant motion of the external 
ear of quadrupeds, we see its importance to them both in col- 
lecting sound, and in judging of its direction. In most men, 
the motion of the ear is lost, but some men still retain it; and 
this is very remarkable, that when the more internal mechan- 
ism of the ear is injured, and ceases to strengthen the sound 
before it conveys it inwards to the labyrinth, the external ear 
resumes the office to which it was originally adapted, and by a 
degree of motion and erection, assists the hearing. In Euro- 
peans, the outward ear is in a great degree flattened to the head 
by the dress ; but in eastern nations, and in ancient statues, 
we see the ears stand prominent, and bear a part in the sym- 
metry and expression of the whole head. The muscles moving 
the cartilages, besides being intended to give motion, appear 
to have a more essential use in giving a due tension to the out- 
ward ear. These cartilages are surrounded with their pecu- 
liar pericondrium ; but as to their vessels and nerves, it seems 
very superfluous to give a minute description of them here. 
When the cartilages are dissected they appear thus : 
Fig. 18. 
a. The helix. It is the outer margin, the edge of which 
is turned over, and forms the cavitas innominata. 
BCD. The antihelix. It is very prominent; of a trian- 
gular shape ; and within the outer rim or margin. 
e. The scapha, which is a depression or cavity on the an- 
terior part of the antihelix. 
F. The ANTITRAGUS. 
o. The tragus. These are the two prominent points which OF THE HUMAN EAR. 
109 
approach each other, and form the margin of the great cavity 
of the ear. 
l. The concha, or great cavity of the ear, and which is the 
trumpet-like opening of the meatus auditorius externus. The 
few pale coloured fibres which are found on the cartilages, are 
scarcely to be recognised as muscles.* 
The lobe of the ear, or that part which hangs down and is' 
pierced for the ear-ring in women and savages, consists of skin 
and cellular substance merely. 
The meatus auditorius externus, is the tube which leads 
into the tympanum. This tube is partly bony and partly car- 
tilaginous. The outer portion of the tube is cartilaginous, and 
about three quarters of an inch in length, and is divided by 
r sures. The internal part of the tube is formed in the bone, as 
,re find upon turning to the description of the temporal bone. 
Glands of the passage.—The cuticle, covering the inside 
of the tube, is very fine, and there project from it many small 
hairs which stand across the passage. Under this skin there 
is a set of small glands which pour their secretion into the tube, 
and are called the glandule cerumenos.e.-}- These glands, 
secreting the wax of the ear, have their little ducts opening 
betwixt the roots of the hairs; and this secretion with the hairs 
which stand across the passage, guards the internal parts of the 
ear from insects. The whole passage, consisting of the canal 
of the temporal bone and the cartilaginous tube placed upon 
it, has an oblique direction. It first passes upward and for- 
ward, and then makes a slight curve to descend to the mem- 
brane of the tympanum. 
This external tube of the ear, being of the nature of a se- 
creting surface, and exposed to the air, is liable to inflamma- 
tion. There follows a dryness of the passages, and then a 
more fluid secretion. If the inflammation of the tube should 
extend within the bones, then, like the affections of all parts 
surrounded with solid bone, the pain is extreme and the danger 
considerable : there is not only suppuration in the tympanum 
and destruction of the membrana tympani, but the disease 
may be still further communicated internally. Hildanus gives 
us an observation of the effects of a ball of glass dropt by acci- 
dent into the ear, in which the inflammation was so extensive, 
and the pain so excruciating, that the whole side of the head 
and even the arms and leg of that side were affected, in conse- 
quence of the brain partaking of the inflammation. Such 
* See Valsalva & Santorini. 
f “ Hee figuram obtinent variam ; major tamen harum pars vel ad ovalem, 
“ vel ad sphcericam accedit colore tinguntur flavo abhumore in earum folliculis 
“ contento qui ob assiduam fibrarum carnearum reticularium pressionem, per 
“ cutis correspondentia foramina in meatus auditorii cavitatem transmittitur.” 
Valsalva de aure bumana, p. 10 110 
OF THE HUMAN EAR. 
things as peas and cherry-stones and pins are very apt to be put 
into the ear by children ; and awkward attempts to extract 
the foreign body, very often push it further in; and acrid fluids 
put into the ear to kill insects, have forced them deeper, with 
such an increase of pain as has thrown the patient into a con- 
dition little short of delirium. A defective or too profuse 
secretion from the glands of the tube will cause a degree of 
deafness : and sometimes the wax is so indurated as to cause 
a very obstinate deafness 
In the foetus, the concha and meatus externus are narrow, 
and there is secreted a thick white stuff, which defends the 
membrane of the tympanum from the contact of the waters of 
the amnios. This, after birth, falls out in pieces along with 
the secretion of the wax ; but, in some instances, it has remain- 
ed and become very hard. The deafness from birth, caused 
by this accident, is often thought to depend upon an organic 
defect, and so is neglected. 
SECTION II. 
OF THE TYMPANUM OR MIDDLE CAVITY OF THE EAR, AND 
ITS DISEASES. 
THE ANATOMY OF THE TYMPANUM. 
In the foetus, the cavity of the tympanum is superficial, com- 
pared with that of the adult; for what forms a tube in the lat- 
ter, is in the former merely a ring, which is attached to the 
squamous portion of the temporal bone :f upon this circular 
bone the membrane of the tympanum is extended. 
The cavity of the tympanum is very irregular ; intermediate 
betwixt the membrane which is extended across the bottom of 
the external tube and the labyrinth or internal ear. It con- 
tains no fluid, as the labyrinth does ; but is really a cavity, 
having a communication with the external air through a tube 
which leads into the fauces. The tympanum communicates also 
* See Valsalva, p. 10. “ Talis surditalis a duodecim annis affligentre cura- 
tio.” The older writers treat of the “ Auditus laesio a sordibus aurium lapi- 
descentibus.” See Bonetus & Jill. Cassertus Placantinus, “ Be auditus organo,” 
lib. 1. cap. 20.p. 90. There is also mention made of an adventitious membrane 
closing up the passage and stretched above the membrana tympani. This is 
produced by a foul secretion, and resembles that which stuff's up the passage 
in the foetus. See FABiucitrsde Chirurg. operat. cap. de aur. Chirurg. Ves- 
eingius Anat. cap. 16. See Experiments on the Solvents of the Ear-wax by 
Dr. Haygarth, Med. Obs. and Inquiries, vol. iv. p. 198. He gives the prefer- 
ence to warm water over every other solvent, 
f See plate 8. fig. 3. OF THE HUMAN EAR. 
111 
backwards with the cells of the mastoid process. The inner 
extremity of the meatus externus forms a circle which is pretty 
regular, and upon which the membrane of the tympanum is 
extended. That part of the cavity qf the tympanum which 
is opposite to the termination of the meatus externus, is very 
irregular. It has in it the foramen rotundum and the foramen 
ovale ; and betwixt these, there is an irregular bony tuberosity 
called the tubercle, from which there stretch back some exceed- 
ingly small spiculse of bone, which connect themselves with the 
margin of the irregular cavity of the mastoid process. On the 
opposite side of the cavity there is a small eminence, with a 
perforation in its centre, called the Pyramid. 
The foramen ovALEf is in the bottom of a deep sinus ; it 
is not strictly of an oval form, but has its lower side straight, 
while the upper margin has the oval curve. This opening leads 
into the vestibule or central cavity of the labyrinth. 
The foramen rotundum is more irregular than the oval 
hole. It does not look directly forwad, like it, but enters on 
the side of an irregular projection: it does not lead into the 
vestibule, but into one of the scalas of the cochlea. In the re- 
cent state of the parts, the periosteum covering the surface of 
the cavity of the tympanum, takes away much of its irregu- 
larity. Where the tympanum leads backward into the cel- 
lulje Mastoidea, this periosteum is also continued. 
The Eustachian tube:): extends forward from the cavity 
of the tympanum, and opens behind the palate.§ In the dry 
bones, the Eustachian tube is more like an accidental fissure, 
than a regular passage, essential to the economy of the ear. 
It appears thus irregular in the bones from the tube being to- 
wards the back of the nose, composed of a moveable cartilage 
covered with a soft membrane; as the tube appi'oaches the 
opening behind the palate, it widens into a trumpet shape ; and 
the extremity of the tube is governed by muscular fibres. 
Within the cavity of the tympanum, on the upper part of the 
Eustachian tube, there is a small canal, giving origin to the 
laxator tympani. This canal has been called the' spoon-like 
cavitij. 
There can be no doubt that the Eustachian tube is designed 
for admitting the free access of air into the cavity of the 
tympanum, that by preserving a due balance betwixt the at- 
mosphere and the air contained within the ear, the motion of 
* When Valsalva, in a case of ulceration and caries on the mastoid process, 
threw in his injections, he found them flowing' out by the mouth: viz. by the 
Eustachian tube through the tympanum. See Val. de aure humana, p. 89. 
f Fenestra ovalis. 
* Iter a palato ad aurem. 
§ By some older writers, the Eustachian tube is called aqueduct, because they 
conceived that humours were evacuated from the tympanum by this passage. 112 
or THE HUMAN EAR. 
the membrane of the tympanum may be free. This, at least, 
we know, that, when the extremity of the Eustachian tube is 
closed, we suffer a temporary deafness, which can be accounted 
for only by the confined air wanting a due degree of elasticity 
to allow the vibration of the membrane of the tympanum. J 
conceive it to be necessary, that the air in the tympanum be 
changed occasionally, which is, perhaps, accomplished by 
some actions of the throat and fauces forcing a new body of 
air into the Eustachian tube. The extremity of the Eusta- 
chian tube, next to the throat, may be temporarily obstructed 
by the cynanche tonsillaris, which is frequently attended with 
pain, stretching from the throat to the ear ; or it may be closed 
by inflammation and adhesion of its mouth, by adhesion of the 
soft palate to the back of the fauces, by polypus in the nose, 
reaching down into the fauces and compressing it.* 
OF THE MEMBRANA TYMPANI. 
The membrane of the tympanum is extended over the cir- 
cular opening- of the bottom of the meatus externus. It has 
a little of an oval shape, and lies over somewhat obliquely, so 
that its lower margin is further inward than the upper. Its use 
is, to convey the vibrations or oscillation of the atmosphere, 
collected by the outer ear, inwards to the chain of bones in the 
tympanum. Although thismembrane be tense,it is not stretched 
uniformly like the parchment of a drum, but is drawn into a 
funnel-like shape by the adhesion tif the long process of the 
malleus to its centre. It consists of two layers of membrane, 
and has, naturally, no perforation in it; and the experiments 
of air, and the smoke of tobacco sent from the mouth through 
the ear, succeed only in those who have had the membrane 
of the tympanum partially, ruptured or eroded by ulceration 
This membrane is transparent; and when we look into the 
tube of the ear, and direct a strong light into it, we observe it 
to be of a shining tendinous appearance. 
The inner lamina of the membrana tympani is very vascu- 
lar. It has, indeed, been said to resemble the iris, both in 
its profusion of vessels, and in the manner of their distribu- 
tion.! This is carrying the conceit of their analogy too far. 
* The following case is from Valsalva:—“Quidam plebeius ulcus gerebat 
“ supra uvulam in sinistra parte, quod quidam earn, quam invaserat, partem 
“ exeserat atque abstuleret sic, ut ulceris cavitas cum extremo sinistrae tuba: 
“ orificio cominunicaret. Igitur quoties homo mollem turundam remediis im- 
“ butam in ulceris cavitatem intrudebat : toties illico sinistra aure evadebat 
“ surdus, talisque permanebat toto cx tempore quo turunda in ulcere relinque- 
“ batur,” p. 90. 
f See Mr. Home’s lecture on the structure and use of the membrana tym- 
pani. Phil. Transact. Part I. 1800. OF THE HUMAN EAlt* 
113 
I have observed an artery of a very large size (compared with 
the surface to be supplied) running by the side of the long 
process or handle of the malleus. In this course, it is giving 
out small branches ; and when the trunk arrives at the extreme 
point of the long process of the malleus, it divides into two 
branches, the extreme subdivisions of which run towards the 
margin of the membrane. This artery is, nevertheless, too 
small to require us particularly to avoid it in the puncturing 
of the membrane for deafness, produced by obstruction of the 
eustachian tube. 
The opinions regarding the muscularity of the membrane 
of the tympanum, shall be reserved until we have considered 
the whole mechanism of the parts in the tympanum. 
OF THE CHAIN OF BONES IN THE TYMPANUM. 
The vibrations of the membrane of the tympanum are 
transmitted to the foramen ovale by four moveable bones; the 
malleus, incus, os orbiculare, and stapes. These bones are 
named from their shape, and the names assist in conveying an 
idea of their form. They are so united by articulation and 
small ligaments, as to form an uninterrupted chain; and while 
they transmit the vibration, their mechanism is such, that they 
strengthen the impulse. They have also small muscles at- 
tached to them, by which it is probable the whole apparatus 
has a power of adapting the degree of tension to the force of 
the impulse communicated to the membrane of the tympanum. 
I conceive that they increase the power of the ear for re- 
ceiving the weaker sounds, and are, at the same time, a 
guard to the internal parts, from such violent shocks as might 
injure the nerve. 
How necessary it sometimes is to damp and suffocate, in 
some degree, piercing sounds, we must all be sensible ; and 
in those who are habitually exposed to the sudden eruption of 
sound, the susceptibility of the nerve is injured, and they be- 
come very deaf. We have, in a late publication, an example 
of this in blacksmiths, in whom, it is common to find a de- 
gree of deafness ; and we find old artillery-men quite deaf, 
from the long practice of their profession. 
The malleus* receives its name from a resemblance to a 
hammer or mallet; it is, in some degree, like a bludgeon ; 
the great head stands obliquely off from the body of the bone 
(if such it may be called) like the head of the thigh-bone. 
* See plate 9. fig. 1. a. 114 
of the human ear. 
Anatomists can scarcely be blamed, if, in describing the pro- 
cesses of this bone, they forget the body. I should consider 
that part as the body of the bone which stretches down from 
the circular margin of the tympanum, and is attached to the 
membrane, or what we should consider as the handle of the 
mallet. This part of the bone stands at an angle with the 
head and neck ; tapers towards the extremity, and is a little 
curved down towards the membrane. From the larger end of 
the body of the bone there stands out an acute process; and 
from the neck attaching the bulbous head to the body of the 
bone, there stands out a very slender process, which is often 
broken off. The great head of the bone does not form a re- 
gular ball to be socketed in the body of the incus; there are 
irregularities in the contiguous surfaces of both the bones. 
The incus* is the second bone of the chain ; it receives its 
name from its resemblance to the blacksmith’s anvil. It more 
resembles a tooth with two roots. On the surface of the body, 
it has a depression like the surface of the first molaris. Into 
this depression of the incus the head of the malleus is re- 
ceived. The shorter of the two processes, and the body of 
the bone, lie on the margin of the circular opening of the tym- 
panum ; and the acute point of this process is turned back into 
the opening of the mastoid cells. The long leg or process of 
the incus hangs down free into the tympanum,f and has at- 
tached to its point the os orbiculare. 
The os orbiculare is like a grain of sand, and is the 
smallest bone of the body : it is a medium of articulation be- 
twixt the incus and stapes. 
The or stirrup is well named, for it has a very 
close resemblance to a stirrup-iron ; the little head is articu- 
lated with the os orbiculare ; the arch of the bone is exactly 
like that of the stirrup-iron, but elegantly grooved within, so 
as to give lightness to the bone. It has a membrane stretched 
across within. The base, answering to that part of the stirrup- 
iron upon which the foot rests, is not perforated, nor is it of a 
regular form, but is flat on one. side, corresponding with the 
foramen ovale. It is this base of the bone which is attached 
to the membrane stretched over the foramen ovale. 
CONNECTION AND MOTION OF THESE BONES. 
The malleus hanging on that part which we have called the 
neck of the bone, has the long handle or body of the bone 
* See plate 9. fig1.1. b. f See plate 4. fig. 1. d. t See plate 9. fig. 1. c. OF THE HUMAN EAR. 
115 
stretched down upon the membrane of the tympanum. It is, 
consequently, destined to receive the oscillations of that mem- 
brane. 
The head of the< malleus is so articulated with the incus, 
that the degree of motion communicated to that bone is much 
increased. 
From this scheme, we see, that the head of the malleus is 
so articulated with the body of the incus, that the centre of 
motion of the incus is in a line drawn through the centre of its 
body, and, consequently, that the extremity of the long pro- 
cess, to which we see the os orbiculare and stapes attached, 
moves through a greater space than that which receives the 
impulse of the head of the malleus. Thus, a very small de- 
gree of motion communicated by the head of the malleus to 
the body of the incus, must be greatly increased in the ex- 
tremity of the long process of the incus, and, consequently, 
this mechanism of the bones essentially assists in giving strength 
to the vibration which is transmitted inward to the seat of the 
nerve. 
The os orbiculare stands simply as a link of communication 
betwixt the extremity of the incus and the upper part of the 
stapes, and its use is evidently to promote the accurate and 
perpendicular motion of this long lever of the incus upon the 
head of the stapes ; for, if this bone had not been so placed, 
the motion of the long lever of the incus must have given an 
obliquity to the impulse upon the stapes. The base of the 
stapes almost completely fills up the foramen ovale. It is 
seated on a membrane which is stretched over the foramen.* 
The stapes, then, acts like a piston on a membrane of much 
* Valsalva has the following observation, see page 24. “ Qlim namque in 
" cqjusdam supdi cadavere surditatis causam in eo sitam inveni nempe quod 
“ indicata membrana in substantiam osseam indurata, unura continuatum os 
•' constituebat cum basi stapedis et margine fenestrse oyalis.” 116 
*F THE HUMAN EAR. 
less circumference than that of the membrana tympani. From 
all which considerations, we may learn how much, and how 
strongly, the agitation of the air in the outer canal of the ear 
is increased, before it strikes upon the fluids of the labyrinth. 
OF THE MUSCLES WITHIN THE TYMPANUM* 
The laxator tympani runs in a fissure of the temporal bone 
on the outside of the eustachian tube, called the spoon-like 
cavity, and is inserted into the long process of the malleus. 
The tensor tympani! runs also by the side of the Eusta- 
chian tube; it is inserted into the body of the malleus; it is a 
long and slender muscle. The external or superior:): muscle of 
the malleus, which is denied by some anatomists to be of the 
nature of muscle, comes down from the upper part of the 
tympanum, and is fixed by a small tendon to the neck of the 
malleus. 
The is the smallest muscle, and is attached to 
the smallest bone. It has a small round fleshy belly, taking 
its origin from the pyramid, and is inserted by a small round 
tendon into the head of the stapes. 
As all these muscles are inserted either into the malleus or 
stapes, and not into the middle bone, it would appear that then- 
operation is chiefly upon the membranes of the tympanum, 
and of the foramen ovale, through the medium of the bone 
immediately attached to them. 
Mr. Home, in the Philosophical Transactions for 1800, as- 
serts that the membrana tympani is muscular; that its fibres 
run from the circumference towards the centre ; and that they 
are attached to the malleus. 
But, what is the supposed use of this muscular membrane ? 
Mr. Home says, it is principally by means of this muscle that 
accurate perceptions of sound are communicated to the inter- 
nal organ; that it is by means of this muscle that the membra- 
na tympani is enabled to vary its degree of tension, so as to re- 
ceive the vibrations in. the quick succession in which they are 
conveyed to it. But we have seen, that the tension and relaxa- 
tion of the membrana tympani is already sufficiently provided 
for: “ The malleus has three muscles by which it is moved; 
“ one of them is called the tensor, from its pulling the malleus 
“ inward and tightening the membrane of the tympanum ; the 
“ other two act in an opposite direction, and relax the mem- 
* Musculus processus minimi mallei. Valsalva. 
I Musculus processus majoris mallei. 
4. Musculus processus minoris. ValsaTva. 
§ This muscle is particularly strong in the horse, where it was first dicoyered 
by Casserius. a brane.”* We should naturally suppose this to be sufficient; 
but according to Mr. Home, these muscles act only to bring 
the membrane into such a degree of tension, as to enable the 
minuter changes of the muscular membrane to have their full 
effect; and that the play of these muscles gives the perception 
of grave and acute tones. 
But the more favourite idea of Mr. Home is, that, upon the 
accurate adjustment of the membrana tympani, the difference 
between a musical ear, and one which is,too imperfect to dis- 
tinguish the different notes in music, depends ; that this judg- 
ment or taste is owing to the greater or less degree of nicety 
with which the muscles of the malleus render the muscular 
membrane capable of being truly adjusted; if the tension be 
perfect, all the vibrations produced by the action of the radi- 
ated muscle will be equally correct, and the ear truly musical. 
Mr. Home proceeds upon the idea, that the membrane of 
the tympanum is like a musical instrument, or, as he expresses 
himself, like a monichord ; but he is fundamentally wrong in 
supposing, that it requires a more delicate organ to be per- 
ceptible of musical tones than of articulate sounds or language. 
In the first place, we may require an explanation of the use 
•of that muscle which is inserted into the stapes. This stape- 
dius muscle would seem to have the same use, and to affect 
that bene in the same manner, in which the muscles of the 
malleus affect it. Surely Mr. Home will not go so far as to 
say, that the membrana fenestra ovalis is also muscular. It 
may be further wrorthy of attention, in considering this subject, 
that whatever affects the membrane of the tympanum, affects 
also the membrane of the vestibule ; that, if the one be relax- 
ed, the other is rendered tense, from the close‘connection that 
exists between them through the chain of bones. 
In the paper already quoted, the following case is given, as 
illustrating the manner in which the loss of the natural action 
of the muscles affects the ear, in regard to its capacity for 
music. A gentleman, thirty-three years of age, who possessed 
a very correct ear, so as to be capable of singing in concert, 
though he had never learned music, was suddenly seized with 
a giddiness in the head, and a slight degree of numbness in 
the right side and arm. These feelings went off in a few hours, 
but on the third day returned ; and for several weeks he had 
returns of the same sensations. It was soon discovered that 
he had lost his musical ear ; he could neither sing a note in 
tune, nor in the smallest degree perceive harmony in the per- 
formance of others. For some time, he himself thought he 
had become a little deaf, but his medical attendant was not 
OF THE HUMAN EAR. 
117 
* Mr. Home’s Lecture. 118 
OF THE HUMAN EAR. 
sensible of this in conversation. Upon going into the country - 
he derived great benefit from exercise and sea-bathing. 
In this case, continues Mr. Home, there appeared to be some 
affection of the brain, which had diminished the action of the 
tensor muscles of the membrana tympani, through the medium 
of the nerve which regulates their actions ; this gradually went 
off, and they recovered their action. 
Another case is given of a young lady who was seized with 
a phrensy which lasted several years, when, from being with- 
out a musical ear, she came to sing with tolerable correctness, 
to the astonishment of her friends. 
Now, to me, the symptoms of both cases argue an affection 
of the brain and of the nerves. It is more probable that the 
delicate auditory nerve should be affected in such a disease, 
than that the portio dura should alone be affected. 
We now proceed to put the incorrectness of this reasoning 
concerning the muscular power of the membrane of the tym- 
panum, in a more particular point of view, leaving to Mr. 
Home’s paper only the merit of ingenuity. Mr. Cooper was 
led to pay particular attention to the action of the membrane 
of the tympanum, from being consulted in a case where the 
membrane was lost with little injury to the function of the 
organ.* He found, that, instead of the total annihilation of 
the powers of the organ, the gentleman was capable of hear- 
ing whatever was said in company, although the membrane of 
both ears was destroyed. He could even hear better in the 
ear in which no traces of the membrane remained. This gen- 
tleman was only in a small degree deaf from the loss of the 
* Case. This gentleman had been attacked, at the age of ten years, with 
an inflammation and suppuration in his left ear, which continued discharging 
matter for several weeks: in the space of about twelve months after the first 
attack, symptoms of a similar kind took place in the right ear, from which 
matter issued for a considerable time. The discharge, in each instance, was 
thin, and extremely offensive to the smell; and in the matter, bones, or 
pieces of bones, were observable. The immediate consequence of these at- 
tacks was a total deafness, which continued for three months; the hearing 
then began to return ; and, in about ten months from the last attack, was re- 
stored to the state in which it at present remains. Having filled his mouth 
with air, he closed the nostrils, and contracted the cheeks; the air thus com- 
pressed, was heard to rush through the meatus auditorius with a whistling 
noise, and the hair hanging from the temples became agitated by the current 
of air which issued from the ear. When a candle was applied, the flame was 
agitated in a similar manner. 
Mr. Cooper then passed a probe into each ear, and he thought the mem- 
brane on the left side was entirely destroyed, since the probe struck against 
the petrous portion of the temporal bone. The space usually occupied 
by themembrana tympani was found to be an aperture without one trace of 
membrane remaining. On the right side, also, a prohe could be passed into 
the cavity of the tympanum; but here, by conducting it along the sides of the 
meatus, some remains of the circumference of the membrane could be dis- 
covered, with a circular opening in the centre, about the fourth of an inch in 
diameter. See Trans, Roy. Soc. for 1800. Part. I. p. 151. of the human ear. 
119 
membrane ; but his ear remained nicely susceptible of musical 
tones, u for he played well on the flute, and had frequently 
“ borne a part in a concert; and he sung with much taste and 
perfectly in tune.” This case puts aside, at once, that theory 
which supposes the musical ear to depend on the minute play 
of the muscles of the tympanum. 
It appears, then, that the membrane of the tympanum may 
be destroyed, that the bones may be washed out by matter 
formed in the tympanum, and still the patient retain the use of 
the organ. But this is only while the stapes retains its place; 
for if this bone be also destroyed, the membrane of the fora- 
men ovale will be destroyed, and the fluids of the labyrinth be 
allowed to flow out, or be otherwise lost. We see that, if the 
chain of bones, and only a part of the membrana tympani be 
left, still this shred of membrane, if it be not detached from 
the handle of the malleus, will vibrate in the air, and com- 
municate those vibrations through the other bones to the ves- 
tibule. We see, also, that though the bones only remain, and 
though they be detached from the membrane of the tympa- 
num, the sound will still be communicated. We see, that a 
rupture of the membrane will not destroy the organization so 
far as to prevent the hearing, unless there follow clots of 
blood or inflammation, suppuration, or fungus. When Mr. 
Cooper found that the membrana tympani could be torn with- 
out injuring the organ, he did not stop short in his investiga- 
tion: but as he found, by daily experience, that obstruction 
of the eustachian tube caused deafness, he thought of punc- 
turing the membrana tympani, as a cure for that kind of 
deafness. He expected, by this operation, to give elasticity 
to the confined air. Accordingly, by puncturing the mem- 
brane of the tympanum with a small trocar, he found; with 
much satisfaction, that the hearing was instantly restored.* 
Valsalva made a good distinction, when he said, that the 
membrane of the tympanum was not absolutely necessary to 
hearing, but only to perfect hearing. We have, in this fact, 
the explanation of the following circumstance, amongst many 
others : “ In naturali surditate a vitio inter tan- 
“ dum istud experimentum, (viz. an ossiculi et membrana 
“ tympani aliquis sit usus auditum,) quod inopinato et feliciter 
“ successit cuidam, qui intruso auri scalpio in aurem profun- 
“ dissime disrupit tympanum, fregitque ossicula et audivit.”f 
* I am only afraid that such punctures will not continue open, as in Valsal- 
va’s experiments they healed up very soon. But, when there is np other in- 
gress and escape to the air in the tympanum, but through the punctured hole, 
it may tend to keep it open. See much of this in Morgagni, Epist. An. XII. 
The membrana tympani is very vascular, I have it red with injection. See 
Ruysch. fig. 9. tab. 9. Epist. An. VIII. 
f Biolanus Encherid. Anat. lib. 4. c. 4. See also Bonetus de Aurium Affect. 
Observ. IV. 120 
OF THE HUMAN EAR. 
Willis also knew, that the destruction of the membrana tym- 
pani did not deprive the person of hearing. Vid. de Anims 
Brutorum. 
§ 2. OF THE DISEASES OF THE TYMPANUM. 
Valsalva denied the existence of periosteum to these 
bones of the tympanum, while he allowed that they had mi- 
nute vessels distributed on their surfaces: but these vessels 
he supposed to creep along the naked bone independently of 
any membrane. This, however, is contrary to all analogy.* 
These bones, as well as the cavity of the tympanum, are 
covered with a very line membrane or periosteum, which after 
a minute injection, is seen covered with many small and dis- 
tinct vessels, as well as with intermediate extravascular effu- 
sions of the injection, as happens in injecting in other mem- 
branes. 
When the tympanum becomes diseased, there is fetid mat- 
ter collected, the membrane of the tympanum suffers, and the 
small bones are sometimes discharged. In such a case, we 
have little farther to do than, by injections, to prevent the 
matter from accumulating. But, let us not confound this se- 
rious cause of deafness with the slighter suppurations in the 
outer passage of the tube : although such suppurations in the 
tube of the ear are apt, when neglected, to destroy the mem- 
brane of the drum or tympanum, and to spread disease to 
these internal parts. 
Authors make a display of the diseases of the membrane 
of the tympanum under the titles relaxatio, tensio nimia, in- 
duratio, and diruptio tympani.f We have seen how little rup- 
ture of the membrane affects the hearing, and may thence 
conclude, that these fantastic imaginings about tension and re- 
laxation of the membrane deserve little notice. The idea of 
relaxation of the membrane of the tympanum, I have no 
doubt, has arisen from the effect of cold and moist weather in 
injuring the hearing, but deafness from this cause is not pro- 
duced by relaxation of the membrane of the tympanum, but 
by swelling of the mouth of the eustachian tube.:]: 
Induration of the membrane is less of an imaginary disease, 
* See Ruysch. Epist. Anat. VIII. tab. 9. 
f Sec Du Verney de Organo Auditus, p. 41. 
4 “ lielaxatio fit ab humore superfluo qui membranam hanc lnunectat et 
“symptoma hoc communiter cum obstructione meatus-ex tumore glandu- 
“ larum conjunctum est, de qua jam supra dictum est: multum autem facit 
s ad difficultatem audiendi in personis qua: defluxionibus catarrhosis obnoxise 
re sunt et per eandem rationem austri nebula et aer pluvius auditum minuunt 
M ut experiri quotidie possumus.” Du Verney loc. cit.p. 41. OF THE HUMAN EAR. 
121 
since there are instances of the membrane becoming thickened 
by inflammation, or cartilaginous, or osseous. The mem- 
brana tympani has been found to adhere to the extremity of 
the incus.* Independently of the want of elasticity, which 
such an adhesion must produce, the mechanical effects, the 
vibration of the bohes, is prevented, and a degree of deafness 
is inevitable. 
Fungous or polypous excrescences from the glands in the 
outer passage of the ear, press back and destroy the mem- 
brane of the tympanum. In the cure of these by the knife, 
caustic, or ligature, there is much danger of injuring the 
membrane. Fungous tumours project from the membrane 
itself. A stroke upon the head will cause bleeding from the 
ear. This is often a sign of concussion of the brain ; that is 
to say, a shock so severe as to rupture the membrane, of the 
tympanum, will most probably injure the brain.f After 
bleeding from the ear, sometimes suppuration follows;j: and 
blood flowing thus from the membrane of the tympanum, or 
other part of the ear, runs back into the cavity of the tym- 
panum, and, filling it with coagulum, causes deafness, by ob- 
structing the free motion of the bones and membrane. Mr. 
Cooper, in a case of this kind, punctured the membrane, and 
after a discharge of blood which continued for ten days, the 
hearing was gradually restored. It is supposed by that gentle- 
man, that the blood effused becomes, in some instances, or- 
ganized, so as to obliterate the tympanum, causing permanent 
deafness. 
The danger in suppuration and caries of the tympanum is, 
that the disease may penetrate backward into the mastoid 
cells and labyrinth, or into the brain itself; for inflammation 
and suppuration so confined amongst the deep recesses of the 
bone, must give great torture, and be apt to extend the mis- 
chief to the brain, or throw out matter on the inside of the 
cranium, the effect of which must be mortal. Such, I think, 
I have seen, to be nearly the effect of suppuration deep in the 
ear. In a man who had been deaf for many years, and who 
was killed by a fracture of the skull, I found the cells of the 
temporal bones fdled with matter, and a thin greenish fluid lay 
betwixt the temporal bone and dura mater. I have since 
found the caries of the petrous horie from this cause fatal. 
* See the London Philosophical Transactions for 1800, Part I. p. 5. 
f When Valsalva found the ventricles of the brain full of blood, and blood 
also in the tympanum, he supposed that the blood in the latter was derived 
from the brain through certain foramina which he discovered. See p. SO. 
± See Valsalva, p. 16. 122 
Valsalva gives us a case of injury of the head, in which the 
patient was relieved while the discharge of pus by the ear was 
free ; but he died when it was entirely suppressed.* 
But, after such suppuration as we should naturally think 
must totally destroy so delicate an organization, we are some- 
times agreeably surprised with a gradual recovery of the 
function. This is owing to the nerve accommodating itself 
or becoming sensible to a less forcible impression, and by the 
ear acquiring new properties. I already mentioned that the 
destruction of the mechanism of the tympanum arose some- 
times from suppurations beginning in the outward ear; and 
we may suppose that the apparatus within the tympanum, when 
partially hurt, is sometimes capable of being, in some degree, 
replaced by a natural process; of which the following case 
from Valsalva is a remarkable proof. 
“ I lately examined the ears of a woman whose hearing had 
been much injured by an ulcer of the tympanum and caries 
of the small bone. I found the ear in which she was deaf 
without a membrana tympani, and the stapes only remaining 
of the bones, and a fibrous mass, like an excrescence, in the 
tympanum. But in the tympanum of the opposite ear, I 
found the membrana tympani almost entirely eroded; so that 
the malleus and incus wrere uncovered, and distinctly seen. 
I could even observe, that the long process of the incus, 
which should be articulated with the head of the stapes, was 
separated from it: but nature had curiously restored the 
eroded membrane. Thus, from the ‘edge of the injured 
membrane, a new membrana tympani was obliquely stretched 
across the cavity of the tympanum, so as to exclude the mal- 
leus and incus from that cavity, but including the head of the 
stapes, as if nature, finding the separated bones no longer ne- 
cessary, had attached the membrane to the head of the 
stapes.”f We have already remarked, that, when the organ 
of one side is injured, we hear so much better with the other, 
that we attend only to the sensation conveyed by it, and 
neglect the duller sensation. The consequence of this is, that 
the bad ear becomes worse. It is much like that effect wrhich 
takes place in eyes by squinting. 
OF THE HUMAN EAR. 
* Valsalva, p. 83. See also a case in Bonetus de Aurium AfFect. Observ. I., 
and Gul. Ballonius Epid. et Ephem. lib. 2. p. 270. When the matter was sup- 
pressed, there came pain of the head, and weight, which yielded to no remedy; 
on dissection, there was found an abscess within the skull. In Bonetus loc. 
cit., a case is related, in which an ignorant surgeon compressed a fistulous 
ulcer in the ear, and so caused the death of the patient. 
t See Valsalva de Aure Humana Tract, p. 79. In those deaf from birth it 
has been twice found that the iticus was wanting. See Bonetus de JLur. Affect. 
Obsero. IV. OF THE HUMAN EAR. 
123 
SECTION III. 
OF THE LABYRINTH. 
The labyrinth is the internal ear : the proper seat of the 
sense of hearing. It consists of the vestibule or middle ca- 
vity ; of the semicircular canals ; and of the cochlea. It has 
its name from those cavities and tubes leading into each other 
in so intricate a manner, as to be followed out with much dif- 
ficulty. 
We understand that the cavities hitherto described in the 
human ear contain air, and communicate with the atmos- 
phere : but, in the cavities we have now to describe, the nerve 
is expanded, and there is, in contact with it, not air, but an 
aqueous fluid. In treating of this division of our subject, we 
have, first, to attend to the forms of the cavities, as seen 
when sections are made in the dry bones next to the soft 
parts contained in those cavities ; and, finally, to the distribu- 
tion of the nerves. To give an idea of the exquisitely delicate 
and complex structure of the many canals, excavations, open- 
ings', fulci, and fovese, of the bones; of the tubuli, sacculi, 
and partitions of the membranes ; and, lastly, of the soft ex- 
pansions of the nerves, without the assistance of plates, would 
be impossible. Albinus, in his academical annotations, begins 
very formally a chapter on the ear ; but, after a few words, 
dismisses the subject, referring merely to his plates. 
The vestibule, or central cavity of the labyrinth, is of an 
oval form, and about a line and a half in diameter.* It has 
two remarkable pits or hollows in it, and has numerous fora- 
mina opening from it into the neighbouring cavities, besides 
lesser foramina for transmitting that portion of the nerve which 
is distributed on the sacs contained in it. One depression 
or fovea is in the back or lower part of the vestibule, another 
in the outer and superior part of it: the one is circular, the 
other semi-oval. Morgagni, and other anatomists, examining 
the dry bones, speculated on their use in reverberating the 
sound in the cavity ; but we must not regard them in this 
unnatural state: on the contrary, they contain in the living 
subjects membranous sacculi filled with fluid, in which mem- 
branes the nerve is finally distributed. That foramen over 
which the stapes is placed, and which is called the foramen 
* Du Verney CEuvres Anatomiques. 124 
OF THE HUMAN EAR. 
ovale, transmits the vibration into the vestibule. For the fo- 
ramen ovale opens directly into the vestibule, and through the 
vestibule, only, does the vibration of the bones in the tympa- 
num reach the other parts of the labyrinth. 
Semicircular canals.—When we have cut into the ves- 
tibule, by taking away that portion of the os petrosum which 
is behind the meatus auditorius internus, ive see five circular 
foramina: these are the openings of the semicircular canals. 
There are three semicircular canals ; and they are distin- 
guished by the terms, the superior or vertical, the posterior 
or oblique, and the exterior or horizontal. The one which, 
in this view, is nearest, is the opening common to the inner 
ends of the posterior and superior semicircular canals. When 
we pass a bristle into this common foramen, and direct it up- 
ward, it passes along the superior semicircular canal, and will 
be seen to descend from the upper part or roof of the vesti- 
bule, almost perpendicularly on the foramen ovale, which is 
open, and immediately opposite. If, again, we pass a bristle 
into the foramen which is near the bottom of the cavity, 
(and which will be just upon the edge of the fracture that 
has laid open the vestibule, if not included in it,) it will come 
out by the opening common .to the superior and posterior se- 
micircular canal. It has passed, then, along the posterior 
canal. The two openings of the exterior or horizontal canal 
are upon the back part of the vestibule ; and the canal itself 
takes a circle which brings its convexity to the confines of the 
mastoid cells. These canals are formed of a very hard brit- 
tle bone, their calibre is so small as not to admit the head of 
a common pin ; they form somewhat more than a half circle ; 
and of each of them, one of the extremities is enlarged like 
the ampullula of fishes. Vnlsalva imagined that the enlarged 
extremities of these tubes were trumpet-like, to concentrate 
and strengthen weak sounds. We shall find, on the contrary, 
that there is in the human ear, as in fishes, a particular ex- 
pansion of the nerve in these extremities of the tube, opposed 
to the circulatory vibration of the fluids in the canals. 
The cochlea.—The third division of the labyrinth is the 
cochlea. It is so named from its resemblance to the shell of 
a snail, or from the manner in which its spiral lamina turn 
round a centre like a hanging stair. It has been minutely, 
but not simply described; and, indeed, there can be nothing- 
more difficult than to describe it in words. 
When the os petrosum is cut from around the cochlea, it is 
seen to be of a pyramidal shape, and to consist of a scroll, 
making large circles at the base, and gradually lesser ones to- 
wards the apex. It is formed in the most anterior part of the OF THE HUMAN EAR. 
125 
petrous bone, and has its apex turned a little dow nward and 
outward; and the base is opposed to the great cul de sac of 
the internal meatus auditorius. 
The spiral tube of 'which the cochlea is composed, forms 
two turns and a half from the basis to the point; and it con- 
sists of the same hard and brittle matter with the semicircular 
canals. When the whole cochlea is cut perpendicularly in 
the dry state of the bones, and when the membranes have 
shrunk away or spoiled, the sides of the spiral canal appear 
like partitions, and are indeed, generally described as such. 
In consequence of the spiral tube of the cochlea having its 
sides cut perpendicularly, the cochlea appears as if divided 
into three circular compartments or successive stages ; but 
there is really no such division ; because the spiral turnings of 
the tube lead from the one into the other. 
Fig. 19. 
Cochlea. 
Jl. Scales. B. Lamina Spiralis. 
C. C. JHodiolus. I). Infundibulum. 
What gives particular intricacy to the structure of this part 
of the labyrinth, is the lamina spiralis. This spiral parti- 
tion runs in the spiral tube of the cochlea, so as to divide it in 
its whole length ; and, in the fresh state of the parts, this lamina 
of bone is eked out by membrane, so as to form two perfectly 
distinct tubes. These tubes are the cochleae : they 
run into each other at the apex of the cochlea; but at the 
base, the one turns into the vestibule, and the other opens into 
the tympanum by the foramen rotundum. 
In the middle of the cochlea there runs down a pillar, which 
is the centre of the circumvolutions of the scalse. It is called 126 
OF THE HUMAN EAR. 
the modiolus. This pillar is of a spongy structure; and 
through it the nerves are transmitted to the lamina spiralis, and 
sides of the cochlea. 
The modiolus opens towards the apex of the cochlea like a 
funnel: and when we take away the outward shell of the apex 
of the cochlea, which is called the cupola, we look into this 
expansion of the upper part of the modiolus as into a funnel; 
it is therefore called the infundibulum. The infundibulum 
is that part which, in a perpendicular section, we should call 
the upper partition.* 
The scalae or divisions of the spiral tube of the cochlea, 
have a communication at their smaller extremities in the in- 
fundibulum ; and as, again, their larger extremities do not 
open into the same cavity, but one into the vestibule, and the 
other into the tympanum, the vibrating motion, which is com- 
municated through the cochlea, must pass either from the 
tympanum into the foramen rotundum, circulate round the mo- 
diolus by the scala tympani, pass into the lesser extremity of 
the scala vestibuli in the infundibulum, and circulate through it 
towards the base of the cochlea, until it pass into the vestibule ; 
or it must pass from the scala vestibuli into the scala tympani. 
The first is the opinion of Scarpa and others. But I trust it 
will afterwards appear, that the oscillations of sound are in 
the first place conveyed into the vestibule, and thence circu- 
late round both the semicircular canals and cochlea. 
In the dry bones, when we cut into the coohlea, there ap- 
pears a spiral tube, as I have described; with a partition run- 
ning along it, and, of course, taking the same spiral turns with 
it towards the apex. This is the bony part of the lamina spi- 
ralis ; but, as the membrane which extends from its circular 
edge quite across the spiral tube of the cochlea, has shrunk 
and fallen away in the dry state of the parts, the lamina spiralis 
is like a hanging stair, and the scalse are not divided into dis- 
tinct passages. In this bare state of the shell of the cochlea, 
when we cut away the cupola or apex of the cochlea, and look 
down upon the infundibulum, we see the extreme point of the 
lamina spiralis rising in an acute hook-like point. 
The modiolus or central pillar, and the lamina spiralis which 
encircles it, are of the most exquisite and delicate structure; 
for, through them the portion of the seventh nerve destined to 
the cochlea is conveyed. To say that the modiolus is formed 
of two central bones, is saying that there is no central column 
at all; or, that the modiolus is the cavity seen in the bottom of 
the meatus auditorius: and to affirm, at the same time, that 
* That is supposing1 the cochlea to rest on its base. OF THE HUMAN EAR, 
127 
the modiolus is a nucleus, axis, or central pillar, is a contra- 
diction in terms. 
When we break away the shell of the cochlea, and break 
off, also, the spiral lamina, we find the little funnel-like depres- 
sion in the bottom of the meatus internus reaching but a little 
way up into the centre of the cochlea.—-We find this depres- 
sion of the meatus auditorius internus perforated with innu- 
merable small holes ; and these foramina are so placed as to 
trace a spiral line, because they give passage to the nerves 
going to the spiral lamina, and must take the form of the 
diminishing gyrations of the lamina spiralis. In the centre of 
these lesser foramina, which are seen in the bottom of the 
great foramen auditorium internum, there is a hole of com- 
paratively a large size, which passes up through the middle of 
the pillar. The modiolus is formed of a loose, spongy tex- 
ture, and resembles the turns of a cork-screw ; and this spiral 
direction is a necessary consequence of the lamina spiralis, 
being a continuation of the spongy or cribriform texture of 
the modiolus. 
Internal periosteum or the labyrinth.—We find that 
the vestibule, the semicircular canals, and cochlea, besides 
their soft contents, which we have yet to describe, have their 
proper periosteum, which, after a minute injection, appears vas- 
cular ; and this, as it has appeared to me, is particularly the 
case with the last-mentioned division of the labyrinth. I see 
very considerable vessels distributed on the vestibule; particu- 
larly, I see their minute ramifications on the circular fovea, 
while very considerable branches are seen to course along the 
semicircular canals. In the cochlea, I see distinct branches of 
yessels rising from the root of the lamina spiralis, and arching 
on the scalae, to the number of ten in the circle ; and, after a 
more minute injection, I have found the osseous part of the 
lamina spiralis tinged red, and the membranous part of a deep 
scarlet.* 
We have observed the meatus auditorius internus to be 
a large oval foramen in the posterior surface of the pars petrosa 
of the temporal bone. This tube transmits the seventh or au- 
ditory nerve. It is about five lines in diameter, but increases 
as it passes inward; and appears to terminate in two deep 
fovea, which are divided by an acute spine. But the audi- 
tory foramen only appears to terminate in these fovea, for they 
are each perforated by lesser holes, which lead into the three 
divisions of the labyrinth, whilst a larger one conveys a portion 
* In a preparation before me, I see a considerable artery derived from tlie 
basilar artery, entering the meatus auditorius internus. From this trunk, I 
conceive that most of these arteries which I have described are derived. 128 
OE THE HUMAN EAR. 
of the nerve through the cavities of the temporal bone alto- 
gether, and out upon the side of the face. This larger fora- 
men is in the upper part of the superior and lesser fovea. It 
first ascends to near the surface of the petrous part of the tem- 
poral bone,* and then descends and turns backward and takes 
a course round the tympanum above the foramen ovale ; and 
close by the posterior semicircular canal. Its termination is 
the foramen stylo mastoideum.f Where this canal of the por- 
tio dura advances towards the surface of the pars petrosa, it is 
joined by a very small canal which extends from the videan 
hole on the forepart of the inclining face of the bone: again, 
after it has passed the tympanum, it is joined by a short canal 
which receives the corda tympani, after it has passed the tym- 
panum. 
The other foramen which is in the upper and lesser fovea of 
the meatus internus, is rather a cribriform plate, as it is a deep 
pit with many foramina in it. These lead into the vestibule, 
and form the macula cribrosa vestibuli.:}: In the inferior 
and larger fovea, we observe several dark spots, which, when 
more narrowly examined, are also distinguished to be cribri- 
form plates, or collections of lesser foramina. We particularly 
observe that conical cavity which is perforated with many little 
pores for transmitting the nerve into the cochlea, and which 
we have already mentioned. From the form ivhich these 
foramina take, this is named the tractus spiralis forami- 
nolosus. These foramina, after passing along the modiolus 
cochleae, turn at right angles, and pass betwixt the plates of the 
lamina spiralis. 
Besides the tractus spiralis foraminolosus the bottom of the 
larger fovea has many irregular foramina, which are like can- 
celli: for very delicate spiculae of bone stand across some of 
them. There is a range of these foramina which stretches 
from the tractus spiralis. This may properly be called the 
tractus calthratus rectus ;§ they do not lead into the 
vestibule, but into the beginning of the lamina spiralis, where 
it divides the two seal* cochleae, and turns the orifice of one 
of them, (by a beautiful curve,) out into the tympanum. 
Nearer to the ridge which divides the two foveae of the mea- 
tus internus, there is a little pit which has also a cribriform 
plate (like that which is in the upper fovea, and is called ma- 
cula cribrosa;) opposite to this point the inside of the vesti- 
* In the foetus, it becomes here superficial, 
f This is the aqueduct of Fallopius, 
f See Scarpa, Plate VII. fig. 1. m. 
§ Tractus spiralis foraminulosi initium. Scarpa of the human ear. 
129 
bule is rough and spongy : it transmits a portion of the nerve 
to the sacculus in the hemispherical sinus of the vestibule.* 
OF THE SOFT PARTS CONTAINED IN THE LABYRINTH. 
Within the vestibule, semicircular canals and cochlea, there 
are soft membranes independent of the periosteum. These 
form sacculi and tubes which contain a fluid, and have the ex- 
treme branches of the.portio mollis distributed among them. 
Betwixt the soft and organized sacculi and tubes and the peri- 
osteum of the osseus labyrmth, a watery fluid is exuded. 
Sacculus vestibuli. The hemispherical and semi-elliptical 
fpvese which we have described in the vestibule, contain, or at 
least receive partially, two sacculi. The Sacculus which is in 
the hemispherical cavity, receives the most convex part of the 
sacculus vestibuli. This sac is distended with a fluid, and is 
pellucid, and fills the greater part of the vestibule; for only a 
part of it is received into the fovea. It forms a complete sac, 
and has no communication with the other soft parts of the laby- 
rinth, though lying in contact with the alveus communis, pre- 
sently to be mentioned; and being surrounded with an aqueous 
fluid, it must receive the impressions or sound in common 
with them. 
Alveus communis ductuum semicircularum.—This 
sacculus lies in the semi-elliptical fovea of the vestibule, or like 
the other sacculus, is in part received into it. This sacculus 
receives the extremities of the tubuli membranacei which lie 
in the semicircular canals ; it is a little bag common to them, 
and connecting them altogether, as in fishes: it is filled with 
fluid, and is so pellucid, as to be distinguished with much dif- 
ficulty.! Upon pressing the common sac, or the ampullulse of 
the semicircular canals, the fluids are seen to circulate along 
the membranous tubes of the canals. These two sacculi in 
the vestibule lie together, and firmly adhere, but do not com- 
municate ; yet (as may be easily imagined) they cannot be 
separated without tearing the partition. 
Tubuli membranacei.—The tubuli membranacei are the 
semicircular tubes which pass along the osseous semicircular 
canals, and to which the latter are subservient, merely as sup- 
porting them. They are connected by means of the common 
alveus in the vestibule, and form a distinct division of the 
organ. 
* Scarpa. 
f Proprio humore turgidus acleo translucet, ut abiongum bullulam aeream 
mentiatur. Scarpa, p. 47- 130 
OF THE HUMAN EAR. 
It was believed by anatomists formerly, that the osseous 
canals had the pulp of the nerve expanded on their perioste- 
um. But we find, on the contrary, that the membranous tu- 
buli do not touch the bones, but are connected with them by 
transparent cellular membrane-like mucus. Each of the semi- 
circular membranous tubes has one extremity swelled out into 
an ampulla of an oval form, answering to the dilated extremity 
of those osseous tubes which we have already described. 
These ampullae have the same structure and use with those 
formerly mentioned in describing the ear in fishes. When the 
central belly of these tubes is punctured, both the ampullae 
and the membranous canals fall flaccid. 
Besides those vessels which we have described running 
along the periosteum of the cavities of the labyrinth, vessels 
also play upon the sacculi and membranous tubes. The am- 
pullae of the tubes are, in a particular manner, supplied with 
blood-vessels.* 
In the cochlea there is also a pulpy membrane, indepen- 
dent of the periosteum ; but of this I can sav nothing from my 
own dissection. 
SECTION IV. 
OF THE NERVE. 
As the seventh pair of nerves arises in several fasciculi , 
they form what would be a flat nerve, were it not twisted into 
a cylindrical form adapted to the foramen auditorium. While 
these fasciculi are wrapped in one common coat, they are 
matted together. In the canal the nerve is divided nearly into 
two equal parts ;f to the cochlea and to the vestibulum and 
semicircular canals. Those fasciculi, which are destined for 
the vestibule, are the most conspicuous ; and on the portion 
destined for the ampullae of the superior and external canal, 
there is formed a kind of knot or ganglion. 
Before the auditory nerves pass through the minute forami- 
na in the bottom of the meatus auditorius, they lay aside their 
coats and become more tender and of a purer white colour : 
and by being still further subdivided by the minute branching 
* “ Cxterum universum hoc canaliculorum membraneorum alveique com- 
“ munis machinamentum sanguiferis vasis instruitur, quorum crassiora, circum 
“ alveum communem, serpentino incessu ludunt: crebra et conferta alia 
“ ampulla imprimis recipiunt ob quam causam rubella; plerumque sunt et 
“ cruore veluti suffusx.” Scarpa, p. 47. 
f Of the portio dura we have already spoken. OF THE HUMAN EAR. 
131 
and divisions of the foramina, they cannot be followed, but 
finally expand in a white pulpy-like substance on the sacs and 
ampullae. We must, however, recollect that there was a dif- 
ference to be observed in the apparent texture of these ex- 
panded nerves in the lower animals : we may observe here, 
also, that part of the nerve which is expanded on the common 
belly or sacculus tubulorum, is spread like a fan upon the 
outer surface of the sac, and has a beautiful fibrous texture ; 
but upon the inside of the sac upon which it is finally dis- 
tributed it loses the fibrous appearance. We must suppose 
its final distribution to be in filaments so extremely minute 
that we may call it a pulp ; though by the term it must not be 
understood that an unorganized matter is meant. 
That part of the nerve which stretches to the ampullae, im- 
mediately divides into an opaque white mucous-like expansion. 
Beyond these ampullae, there has been no expansion of the 
nerve discovered in the membranous tubes. 
The sacculus vestibuli* is supplied by a portion of the nerve 
which perforates the macula foraminulosa in the centre of the 
osseous excavation, or that which receives into it part of the 
sac. This part of the nerve is expanded in a soft mucous- 
like white matter in the bottom and sides of the sac. 
A division ot the nerve, as we have already explained, pas- 
ses from the meatus auditorius internus through the cribriform 
base of the modiolus into the cochlea. Owing to the circular 
or spiral form of the foramina when the nerve is drawn out 
from the meatus, its extremity appears as if it had taken the 
impression of these foramina from the extremities of the torn 
nerves, preserving the same circular form. These nerves, 
passing along the modiolus and scake cochleae are in their 
course subdivided to great minuteness. Part of them perfo- 
rate the sides of the modiolus, whilst others pass along betwixt 
the two plates of the lamina spiralis, and out by the minute 
holes in the plates, and from betwixt their edges. Lastly, a 
central filament passes up through the centre of the modiolus, 
and rises through a cribriform part into the infundibulum to 
supply the infundibulum and cupola. 
Where the nerves pass along the lamina spiralis, their deli- 
cate fibres are matted together into a net-work. According to 
the observations of Dr. Monro they are quite transparent on 
their extremities. 
' i, e.In opposition to the sacculus tubulorum. 132 
CHAP. V. 
OF HEARING IN GENERAL. 
When aerial undulations were, by the experiments on the 
air-pump, first proved to be the cause of sounds, philosophers 
looked no further to the structure of the ear than to discover 
an apparatus adapted to the reception of such vibrations.— 
When they observed the structure of the membrane of the 
tympanum, and its admirable capacity for receiving these 
motions of the atmosphere, they were satisfied, without con- 
sidering the immediate objects of sensation. In the same way 
an ignorant person, at this day, rest satisfied with the 
fact that sound was received upon the drum of the car. But 
after so minutely explaining the anatomy of the ear, it be- 
comes us to take a general survey of a structure the most beau- 
tiful which the mind can contemplate. We cannot say'that it 
surpasses in beauty the structure of other parts of the body : 
but the parts are adapted to each other, in a manner so simple, 
efficient, and perfect, that we can better understand and ap- 
preciate the harmony of their structure than that of organs 
which perform their functions by qualities and actions almost 
entirely unintelligible to us. 
We see that the external ear collects the vibrations ol sound 
as it moves in the atmosphere with circular undulation from 
the sonorous body : here we may observe, that where the ne- 
cessities of animals require them to be better provided with 
this external part of the organ than man, the superiority is 
only in- the simple perception of sound ; while man, from the 
perfection of the internal organ, excels all animals in the ca- 
pacity of the ear for articulate and musical sounds. 
From the external ear we observe, that the trumpet-like 
tube conveys the sound inward to the membrane of the tym- 
panum. Behind the membrane of the tympanum, there is a 
cavity, which, in order to allow of the free vibration of the 
membrane, contains air. When this air is pent up, by the 
swelling, or adhesion of the eustachian tube, the elasticity 
of the air is diminished, and the membrane prevented from 
vibrating.* 
* See Recherche,s. See. relatives a Vorgane de Vouie et a la propagation des sons, 
nar M. Perolle, Societ. li. de Medecine, tom. iii. OF HEARING IN GENERAL. 
133 
In the tympanum we have seen that the operation of the 
chain of bones is to increase the vibration received upon the 
membrane of the tympanum, and to transmit it to the mem- 
brane of the foramen ovale. In the cavity of the tympanum 
we observed two foramina, the foramen ovale and the fora- 
men rotundum, both of which lead into the labyrinth; but 
one of them (the foramen ovale) into the vestibule, the other 
(the foramen rotundum) into the scala of the cochlea: now it 
becomes a question, whether the oscillations of sound pass by 
one or by both of these foramina ? 
It is the opinion of many, that while the chain of bones re- 
ceives the motion of the membrane of the tympanum, the 
motion of this membrane at the .same time causes a vibration 
of the air in the tympanum which reaches the foramen rotun- 
dum, and thus conveys a double motion through the cochlea, 
In the labyrinth there is no air, but only an aqueous fluid: 
now this, we have seen, conveys a stronger impulse than the 
atmosphere; stronger in proportion to its greater specific gra- 
vity and want of elasticity ; for an elastic fluid like air may 
be compressed by concussion, but an inelastic fluid must trans- 
mit fairly every degree of motion it receives. But if the fluid 
of the labyrinth be surrounded on all sides ; if, as is really the 
case, there can be no free space in the labyrinth, it can par- 
take of no motion, and is ill suited to receive the oscillations 
of sound. Against this perfect inertia of the fluids of the 
labyrinth, I conceive the foramen rotundum to be a provi- 
sion. It has a membrane spread over it, similar to that which 
closes the foramen ovale. As the foramen ovale receives the 
vibrations from the bones of the tympanum, they circulate 
through the intricate windings of the labyrinth, and are again 
transmitted to the air in the tympanum by the foramen rotun- 
dum. Without such an opening there could be no circulation 
of the vibration in the labyrinth ; no motion of the fluids 
communicated through the contiguous sacculi, nor through the 
scalae of the cochlea ; because there would be an absolute and 
uniform resistance to the motion of the fluids.—But, as it is, 
the provision is beautiful. The membrane of the foramen 
rotundum alone gives way of all the surfaces within the laby- 
rinth, and this leads the course of the undulations of the fluid 
in the labyrinth in a certain unchangeable direction. 
To me it appears, that to give a double direction to the mo- 
tion of the fluids, or to the vibration in the labyrinth, far from 
increasing the effect, would tend to annihilate the vibrations 
of both foramina by antagonizing them. The common idea 
is, that there is a motion communicated through the mem- 134 
brane of the foramen rotundum along the scala tympani, and 
another through the foramen ovale into the vestibule, and 
through the vestibule into the scala vestibuli; and that the con- 
cussion of these meet in the infundibulum of the cochlea.— 
But as there is no space for motion in the fluids, in either the 
one or other of these tracts, the vibration must have been 
received in the infundibulum at the same time that the motion 
was communicated to the membrane of the foramen ovale and 
rotundum ; for if a tube full of water, a mile in length, loses 
one drop from the extremity, there must be an instantaneous 
motion through the whole to supply its place. The evident 
consequence of this double motion would be (if they were of 
the same strength) to suppress all motion or vibration in the 
fluids of the labyrinth. 
But we have shown that the strength of vibration communi- 
cated to the foramen ovale and foramen rotundum are not the 
same: for the mechanism of the bones in the tympanum is 
such as to accumulate a greater force or extent of motion on 
the membrana ovalis than is received upon the membrana 
tympani; therefore the lesser vibration which is communi- 
cated through the medium of the air in the tympanum, can- 
not be supposed capable of opposing the stronger vibration 
which circulates from the foramen ovale through the laby- 
rinth, and returns by the foramen rotundum. Besides, the air 
in the tympanum has a free egress, and cannot therefore 
strike the membrane on the foramen rotundum forcibly. 
For these several reasons, I conceive that the following ac- 
count of the manner in which the sound is conveyed is erro- 
neous :—“ Et quo ad zonam cochleae spiralem quoniam altera 
“ cochleae scala in vestibulo patet, altera a fenestra rotunda 
“ initium sumit, atque earum utraque aqua labyrinthi repleta 
“ est, et scaloe in apice cochleae simul communicant, zona spi- 
“ ralis inter duas veluti undas sonoras media, a tremoribus per- 
“ vasim stapedis, simulque ab iis per membranam fenestra ro- 
“ tundtv advectis utraque in facie percellitur et una cum pen- 
“ cillis acaustici nervi per earn distributis contremiscit: quibus 
“ porro omnibus, in ampullis videlicet caniliculorum semicir- 
ec cularium, alveo eorum communi, sacculo vestibuli spherico 
“ et lamina cochleae spirali acaustici nervi affectionibus audi- 
u turn contineri nemo non intelligit.1’* 
As to the immediate seat of the sense of hearing, there can- 
not, after what has been explained regarding the distribution 
of the nerves, remain any controversy ; though before the 
structure of the ear was so well understood, some imagined 
0F HEARING IN GENERAL. 
* Scarpa, p. 61. OF HEARING IN GENERAL.. 
135 
that the vestibule, others that the middle part of the semicir- 
cular canals, was the seat of hearing ; others, again, that the 
lamina spiralis was better adapted for receiving the vibrations 
of sound. It is evident that the soft expansion of the nerve, 
in all the three divisions of the labyrinth, is destined to re- 
ceive the undulation of the contained fluids, and that this mo- 
tion of the fluids gives to the nerve, or to the nerve and brain 
conjointly, the sensation of hearing. 
Since we have, in some measure, traced the structure of the 
ear from the animals of a simple structure to those of a more 
complicated organization, and have observed some parts of 
the ear common to all animals, some peculiar to certain or- 
ders ; and since all have the sense of hearing, more or less 
acute, it becomes natural to inquire what are the parts of the 
organ the most essential to the mere perception of sound, and 
what parts conduce to a more perfect state of the sense. 
All the external apparatus of the ear is not necessary to give 
the animal the simple perception of sound.—There are many 
classes of animals altogether without them, and even in man 
we see that they are not absolutely necessary ; since when de- 
prived of them by disease, man still enjoys the sense. He is 
deprived of no essential variety of the sensation : he is capable 
of perceiving the distinctions of articulate sound ; and still 
possesses his musical ear. The external apparatus of the ear, 
the membrane of the tympanum, the little bones, and even 
the external ear, only receive, concentrate, and increase the 
tremors of the external air, and render the slighter impres- 
sions audible. 
It would appear that the simple sac of the vestibule is suffi- 
cient to receive the impression in some animals, and that in 
many the vestibule and semicircular canals form solely the or- 
gan of hearing. It is evident, therefore, that these are the 
most essential parts. We see also an intention in the strict 
similarity of figure and place in these canals through all the 
varieties of animals, from fishes to man. It would seem to 
indicate, that there is in their form and position a peculiar 
provision for the oscillation of sound producing the full effect. 
We find, however, that the cochlea is imperfect in birds: 
and that it is fully formed only in man, and in quadrupeds: 
we must, therefore, conclude, that it is subservient to the more 
exquisite sensations. I do not conceive that the cochlea or 
any part of the organ particularly conduces to the bestowing 
of a musical ear, although it is by hearing that we are capable 
of the perceptions of melody and harmony, and of all the 
charms of music ; yet it would seem, that this depends upon 136 
OF HEARING IN GENERAL. 
the mind, and is not an operation confined to the organ. It is 
enjoyed in a very different degree by thbse whose simple fa- 
culty of hearing is equally perfect.* 
Even after studying, with all diligence, the anatomical 
structure of the ear, we cannot but be astonished with the va- 
rieties to be found in the sensation ; for example :—“ The ear 
w is capable of perceiving four or five hundred variations of 
“ tone in sound, and probably as many different degrees of 
“ strength ; by combining these, we have above twenty thou- 
w sand simple sounds that differ either in tone or strength, sup- 
“ posing every tone to be perfect. But it is to be observed, 
“ that to make a perfect tone, a great many undulations of 
u elastic air are required, which must all be of equal duration 
u and extent, and follow one another with perfect regularity; 
u and each undulation must be made up of the advance and 
a recoil of innumerable particles of elastic air, whose motions 
u are all uniform in direction, force, and time. Hence we 
u may easily conceive a prodigious variety in the same tone, 
u arising from irregularities of it occasioned by constitution, 
“ figure, situation, or manner of striking the sonorous body ; 
“ from the constitution of the elastic medium, or its being dis- 
“ turbed by other motions ; and from the constitution of the 
u ear itself upon which the impression is made. A flute, a 
“ violin, a hautboy, a French horn, may all sound the same 
“ tone, and be easily distinguishable. Nay, if twenty human 
“ voices sound the same note, and with equal strength, there 
w will still be some difference. The same voice, while it re- 
“ tains its proper distinctions, may yet be varied many ways : 
“ by sickness or health, youth or age, leanness or fatness, good 
“ or bad humour. The same words, spoken by foreigners and 
“ natives, nay by different provinces of the same nation, may 
u be distinguished.”! 
That this variety of sensation does not entirely depend upon 
the structure, but is the operation of the sense and intellect 
conjointly, appears from the long experience which is requisite 
to give this perfection. Nature is bountiful in providing the 
means of simple and acquired perception, but the latter is the 
result of long experience and continued effort, though we have 
lost the feeling of its being originally a voluntary effort. 
* See Reid’s Enquiry. 
f Reid’s Enquiry, p. 98. DISEASES OF THE INTERNAL EAR. 
137 
CHAP. VI. 
OF THE DISEASES OF THE INTERNAL EAR. 
Of all the causes of deafness, that which proceeds from an 
organic disease of the brain, is, of course, the most dangerous. 
In apoplectic affections, with faltering of speech and blind- 
ness, deafness is also produced by the general affection of the 
brain. But worst of all is the case where a tumour of the 
brain, or betwixt the cerebrum and cerebellum, compresses 
the origin of the nerves.* I have, however, observed, that a 
tumour in the vicinity of the origin of the auditory nerve, 
though it ran its course so as to prove fatal, had rather a con- 
trary effect on the organ of hearing; and while the pupil of 
the eye remained stationary, and the man saw indistinctly, he 
had a morbid acuteness of hearing. This had probably been 
produced by the surrounding inflammation having extended to 
the origins of the auditory nerves. The auditory nerve often 
becomes morbidly sensible, and the patient suffers by the 
acuteness of perception, or is distressed with the tinnitus au- 
rium, which is, in this case, analogous to the flashes of light 
which sometimes affect the eye in total darkness, and which 
those experience who are totally blind or have cataract. So 
morbidly acute does the sensation sometimes become, that the 
slightest motion of the head will excite a sensation like the 
ringing of a great bell close to the ear.f With delirium, ver- 
tigo, epilepsy, hysteria, the increased sensibility of the organ 
becomes a source of painful sensation. 
In apoplectic affections, with faltering of speech and blind- 
ness, there is also deafness ; because the affection of the brain 
is general. With a paralytic state of the muscles of the face, 
there is a deafness of the corresponding ear, if the affection of 
the nerve be near the brain; which is explained by the strict 
connection betwixt the auditory nerve and the nervus commu- 
* Vidit Clariss. Dom. Drelincurtius Tumorem steatomatis consistentia pug- 
nique magnitudine, cerebrum et cerebellum inter, eo precise loco ubi cona- 
riumutriquesubsteritur choroidis plexus alac, spatiosemestriasensibili Issione, 
cxcitatem primo, surditatem subinde, omnium denique sensuum et functio- 
num animalium abolitionem et necem ipsam intulLsse.” Bonet. vol. i, p. 123. 
ob. 53. In Sandifort Obs. Anatom. Path. tom. i. p. 116. there is an instance in 
which the auditory nerve had a cartilaginous tumour adhering to it. 
f F. Hoffmann. Consult, et Respons. Cas. xxxix. We must not, however, 
take his reasoning after what we have seen of the structure of the ear, that 
viscid petuita, separated in the concha, cochlea, and labyrinth, resolved into 
halitus endeavouring to escape, produces the susurrus et tinnitus aurium. 138 
DISEASES OF THE INTERNAL EAR. 
means faciei. From observing the course of the nervous com* 
municans faciei through the temporal bone, and its connec- 
tions in the tympanum, we understand why, in violent tooth- 
ach and in the tic douloureux, we find the eustachian tube 
and root of the tongue affected. The ear is sometimes af- 
fected by sympathy of parts: for example—from foulness of 
the stomach and bowels ; and the same reason may be assigned 
for the complaint of hypochondriacs, that they are molested 
with strange sounds. And in the case of intestinal worms, we 
find the patient complaining of murmuring and ringing in the 
ears.* Of the organic diseases of the labyrinth, there is little 
on record. It would appear, that the fluids become often so 
altered in their consistence as to prove an absolute destruction 
to the organ. Mr. Cline found in a person deaf from birth, that 
the whole labyrinth was filled with a substance like cheese. 
A disease of the auditory nerve, like that of the retina in 
the gutta serena, is no unfrequent complaint.f 
We ought, at all events, before proposing any operation on 
the ear, to observe whether the disease be not in the seat of 
the sense, and such as will not yield to any practice ; other- 
wise, as in the more important operations when done in cir- 
cumstances which preclude the possibility of success, the pub- 
lic is impressed with its inefficacy and danger, and we are pre- 
cluded from giving relief on occasions more favourable for our 
operations. 
Deafness, in acute fever, is a good sign ; because, say au- 
thors, it argues a metastasis of the morbific matter. We 
should rather say, because it argues a diminution of the mor- 
bid sensibility of the brain4 But the surcharge of the vessels 
of the brain or of the auditory nerve will also produce deaf- 
ness and unusual sensations in the ear ; as in suppression of the 
menses and haemorrhoids, in surfeit, &c. in which cases it is 
often preceded by vertigo and headach. 
There occurs a very curious instance of analogy betwixt the 
ears and eyes, in the following cases :—u A certain eminent 
musician, when he blew the German flute, perceived at the 
same time the proper sound of it and another sound of the 
same rhyme or measure, but of a different tone. His hearing 
* Hoffmann. Med. Consult. Boerbaave. The sympathy is sometimes exerted 
in another way :—“ Ex musices tonitru aut sola meatus auditorii externi con- 
“ trectatione, vomitus urina: incontinentia.” Sauv. 
■j" Dysecoea (atonica) sine organorum sonos Jransmittentium vitio evident?. 
Cullen. Cophosis Sanv. Cophosis a Parucusi distinguitur. ut amaurosis ab <mi- 
biyppia respectiva. Sauv. 
t But the difficulty of knowing when the deafness is the result of disease, 
or malconformation in the parts transmitting the sound to the nerve, and when 
in the brain and nerve, has led to more uncertainty and confusion with regard 
to the species and varieties of the disorders of the ear than in the eye ; where 
the transparency of the humours assist in the definition. DISEASES OF THE INTERNAL EAR. 
139 
seemed thus to be doubled. It was not an echo; for he heard 
both sounds at one and the same moment: neither were the 
sounds accordant and harmonious, for that would have been 
sweet and pleasant to his ear. Having for several days per- 
sisted in his attempts, and always been shocked with this grat- 
ing sound, he at last threw his flute aside. The day before 
he first became sensible of this strange affection, he had im- 
prudently walked in a very cold and damp evening, and was 
seized with a catarrh in the right side. Whence, probably, 
it arose that the natural tone of that ear was altered: the 
sound appeared more grave and dissonant, from that received 
by the left ear. Having recovered from the catarrh, the dis- 
tinct hearing of his ear was restored.” 
Sauvage, who relates this case, subjoins another:—“ Very 
lately,” says he, “ a foreigner came for advice in a similar 
situation. He complained that when any person spoke to him, 
he heard the proper sound of the voice, and at the same time 
another sound accompanying it an octave higher, and almost 
intolerable to him. As it must have happened that if the ac- 
companying sound had preserved the true octave above the 
voice, and been synchronous with it, the ear would have rer 
ceived them as one sound, and been pleased with their con- 
cord : it is probable that the accompanying sound was not in 
unison with the true.” Sauvage, vol. in, p. 352. BOOK III 
OF THE NOSE AND OF THE ORGAN OF SMELLING 
OP THE SENSE OF SMELLING. 
SMELLING seems to be the least perfect of the senses. It 
conveys to us the simplest idea, and is the least subservient 
to the others. The sensations it presents to us we can less 
easily recall to memory : and the associations connected with 
it are less precise and definite than those of the senses of 
hearing and seeing ; finally, we should lose it with less regret 
than any other. , 
Animal and vegetable bodies, during their life, growth, pu- 
trefaction, and fermentation, and, most probably, all bodies 
whatever, are perpetually giving out effluvia of great subtility. 
Those volatile particles repelling each other, or diffused in the 
atmosphere, are inhaled by the nose, and convey to the pitui- 
tary membrane of the nose the sensation of smell. Even in the 
outward form and structure of the nose, there is a relation t«* 
the exercise of the sense; the lateral cartilages of the nose, 
or those which form the nostrils, possess a degree of elasticity 
adapted to preserve the passage open and free. They have 
muscles adapted to move them, to expand them when greater 
freedom of respiration is required, and to contract them in or- 
der to diminish the stream of air, and to give it more force to 
penetrate to the upper cavities of the nose. The cartilage 
which joins to the septum of th£ nose is also flexible and 
moveable by muscles, which curve the nose or draw down the 
point by which in smelling, the air, which in ordinary respi- 
ration passes freely backwards, is directed upwards to the seth- 
moid bone; these cartilages perform another office in giving 
that flexibility to this prominent feature, which enables it to 
dude injuries and at the same time protect the bones of the OF THE SENSE OF'SMELLING. 
141 
nose : but their chief use is in connection with the sense; for 
it may be observed, that when we draw the air in in smelling, 
the nostrils are compressed, which gives more force to the air 
received, and at the same time the direction of the stream of 
air is changed. When we breathe with the nostrils, stationary 
or expanded, the air passes directly backwards, but when it is 
drawn in in smelling, (the nose being drawn down,) a direction 
upwards is given to the stream of air, so that it is made to 
circulate about the cells of the sethmoid bone, where the 
olfactory nerve is expanded. 
Immediately within the nostrils, there are two cavities sepa- 
rated by the bony partition, which has been already described 
in treating of the bones. These cavities enlarge as they 
proceed inward, and open backward into the throat, and con- 
sequently, communicate with the mouth. They extend upward 
and sideways into the cells of the bones of the face; and the 
pituitary membrane is extended over the surfaces of these 
winding passages, and over the irregular surfaces of the nose, 
formed by the projecting cartilages of the aethmoid and lower 
spongy bones; which, also, have already been sufficiently 
described. 
The cavities of the nose lead into many cells in the bones of 
the face, which, though not the immediate seat of the sense, 
are subservient to the organ by permitting a circulation of the 
air, and thus carrying the effluvia into contact with the nerve. 
No doubt these cavities are also useful in giving vibration and 
tone to the voice. The cavities of the nose are continued 
upwards into the frontal sinuses, and into the cells of the 
sethmoid bone; backward and upward into the sphenoid sinus; 
and upon the sides into the antra Highmoriana or sinuses of the 
upper maxillary bones. 
The membrane covering the surface of these bones is called 
the membrana schneideri ana, the mucous or pituitary mem- 
brane. It is of a glandular structure, or is lubricated by the 
mucus discharged by the follicules on its surface. This secre? 
tion on the surface of the membrane, is to defend its delicate 
and sensible structure from the effects of the air, while it pre- 
serves the sensibility of the surface and the delicate expanded 
nerve. It seems of a nature to allow the effluvia to pene- 
trate it. 
A very particular provision has been made against the too 
powerful effect of smells while the membrane is inflamed, and 
consequently, in a state of great sensibility. When the mem- 
brane is inflamed, the secretion is altered, and the effluvia 
does not penetrate, nor does it affect the nerve in its state of 
extreme sensibilitv. 142 
OF THE SENSE OF SMELLING. 
We have already described the course of the first pair of 
nerves or the olfactory nerves, and also those branches of the 
common nerves which are distributed to the membrane of the 
nose. These, it were superfluous to recapitulate here. The 
olfactory nerve alone is the organ of smelling, and the branches 
of the fifth pair bestow merely the common sensibility which 
is enjoyed promiscuously over the body. 
I have traced branches of the fifth nerve into all the cavities 
of the face, and we feel that they possess sensibility. Thus in 
applying volatile salts to the nostrils, we can distinguish a pain- 
ful sensation rise into the frontal sinuses different from the 
sense of smelling. When the root of the nose has been 
broken in and the cavity opened, experiments have been made 
by sending effluvia upwards into the frontal bone, and no sense 
of odours was experienced ; but when they were admitted 
downwards to the sethmoid bone, the first nerve was affected, 
and the sense exercised. This sensible and nervous mem- 
brane, being also glandular and secreting, is very vascular; 
and this vascularity, this glandular structure, and its exposed 
state, makes it liable to frequent disease : and, when diseased, 
when tumours and polypi form in it, we must never forget the 
extreme thinness and delicacy of the surrounding bones, 
which, when they are either pressed upon by tumours, or have 
their membranes eroded, are soon totally destroyed. It is 
with manifest design, that the organ which so particularly 
admonishes us of the effluvia diffused in the air we breathe, 
should have been placed in the entrance to the canal of the 
lungs. It is, in some measure, a guard to the lungs, as the 
sensibility of the tongue guards the alimentary canal. That 
the humidity of the membrane either preserves the sensibility 
of the nose, or is a solvent, in which the effluvia dissolving 
affect the nerves, is evident; for the sense is lost when the 
membrane becomes dried. The sensibility is also affected in 
various ways by too abundant a mucous discharge, or by an 
alteration of its natural properties ; by the infarction and 
thickening of the membrane, as in ozsena ; by obstructions 
preventing the current of air through the nose, as in polypi, &c. 
The acuteness of sensation in this organ is most probably 
lost by our habits, by our relying on other senses, by the in- 
cessant application of artificial odours to the organ. Those 
who have believed in the variety of the human species, and 
the approximation of some tribes to the brute, dwell much 
on the acuteness of sensation enjoyed by negroes, and their 
wider nostrils.* 
* Pallas says, the Calmuck by applying his nose to the hole of a fox, or any 
other beast, can tell whether he be at home or not.—See While of Munchester OF THE SENSE OF SMELLING. 
143 
There is nothing more curious than the spontaneous exer- 
cise of the organs of the senses. Thus we have bad taste in 
the mouth. Ringing in the ears. Sparks of tire before the 
eyes, when there has been no outward impression made upon 
the organ; and so have we rarer examples of disease putting 
even the organ of smelling into exercise. A young gentleman, 
a student, was attacked with a complaint in his Schneiderian 
membrane, which changed the nature of its secretions. Dur- 
ing this disease he was assailed with the most disagreeable 
odours, a circumstance not so uncommon ; but the unpleasant 
exercise of the sense was sometimes relieved by his experi- 
encing the most delightful and fragrant effluvia, which after all 
were not in existence, but proceeded either from the sponta- 
neous operation of the organ of sense, or from morbid irrita- 
tion upon it. 
There has £>een a most interesting communication made to 
me by Mr. of two examples of ossification in the an- 
terior part of the falx, in two men who were related to each 
other, and who, during the latter part of their lives, were dis- 
turbed by the most offensive smells, which had no existence 
but in/ the irritation of these bony excrescences on the olfac- 
tory nerve. BOOK IV. 
OF THE MOUTH, SALIVARY GLANDS, AND ORGAN 
OF TASTE. 
CHAP. I. 
OF THE MOUTH AND TONGUE. 
THE mouth is that cavity anterior to the velum or fleshy 
palate ; the posterior cavity is the fauces ; the mouth is for 
mastication and speech, the posterior cavity is a common pas- 
sage, admitting the food to be conveyed into the oesophagus, 
and the air to be drawn in from the nostrils into the trachea. 
The lips and cheeks are formed of the skin and reflected 
mucous membrane, with muscular fibres intervening to give 
them pliancy and motion, and with minute glands to discharge 
the moisture on their inner surfaces. 
The glands of the lips are called glandulx labiales and are 
very numerous, those of the cheeks are called the glandulx 
buccales. 
OF THE TONGUE. 
The body of the tongue consists of muscular fibres, with 
intermingled fat and cellular membrane; and the muscles 
which chiefly compose it, are the linguales, styloglossi, and 
genioglossi muscles. 
The base of the tongue is that part which is connected with 
the os hyoides, the apex is anterior. 
The surface applied to the roof of the mouth is called 
dorsum ; and on this surface there is to be observed a middle 
line, dividing the tongue into two lateral portions ; a division 
which is very accurately preserved in the distribution of the 
blood-vessels and nerves of either side. On the dorsum, to- 
wards the base, the surface is rough with the papillae maxima? 
and foramen caecum Morgagni.* These papillae are like small 
glands seated in little superficial fossulae, so that their broad 
mushroom-like heads alone are seen ; but they are connected 
* Adversar. Anat VI. Animad. XGTTT. OF THE MOUTH AND TONGUE. 
145 
with the bottom of the fossulse by short stems or necks. This 
is considered a glandular apparatus. The foramen caecum is, 
in truth, only an enlarged apparatus of the same kind, for, in 
the bottom of this foramen, many glandular papillae stand up ; 
and in its bottom small foramina have been observed, which 
are generally conceived to be the mouths of small salivary 
ducts. Morgagni himself, however, seems only to have seen 
a small duct opening into this foramen in one subject of many 
which he examined. In Haller’s opuscula there is a disserta- 
tion on the Duct of Cosckxvizianus, which was supposed to carry 
the saliva from the sublingual gland to the middle of the 
tongue, and also into the throat, but it turns out to be a vein 
only. It is curious to observe the necessity the author dis- 
covered for these ducts, when he thought he had found them.* 
This secreting mucous surface begins here, towards the root 
of the tongue, to resemble the glandular structure of the eso- 
phagus, which by bedewing the surface of the morsel, fits it for 
an easy passage through the gullet. To me it seems that this 
roughness of the root of the tongue is a provision for the de- 
tention of the sapid particles, and the prolonging of the sensa- 
tions of taste. 
The papilla of the human tongue are divided into four 
classes. 1. These larger papillae upon the root of the tongue 
are the truncatae; and they are often studded on the dorsum 
of the tongue in a triangular form. 2. The fungiformes are 
obtuse papillae found more forward on the tongue; they are 
little hemispherical tumid papillae, with an obtuse surface. 
These are interspersed among the 3d division, the most nume- 
rous and universally prevalent papillae, viz. villosi or conoideae; 
they are, as Soemmerring says, of various forms, angular, co- 
nical, obtuse. 4. The vaginatae are the more important pa- 
pillae, however ; they are endowed with peculiar sensibility to 
sapid bodies; are to be distinguished by their superior redness 
and brilliancy, and are placed upon the point and edges of the 
tongue. 
The tongue is invested with the cuticle and rete mucosum, 
like the skin in other parts. The lower surface of the tongue 
is similar to the general lining membrane of the mouth, being 
a villous and secreting surface. It is reflected off upon the 
bottom of the mouth. It forms here the frenulum lingua. 
This ligament seems evidently intended to limit the motion 
of £he point of the tongue backwards. I believe a very false 
opinion has much prevailed, that the shortness of this ligament, 
* Vater, who injected these ducts, found them terminating in a gland near 
the os hyoides; and his opinion was, that they had even a connection with the 
thyroid gland. Heister was of the same opinion!, 146 
OF THE MOUTH AND TONGUE. 
or its being continued too far forward toward the point of the 
tongue, prevents the child from sucking. The tongue, as I 
conceive, would sufficiently perform the necessary action on 
the mother’s nipple, although its lower surface were univer- 
sally adhering to the bottom of the mouth. But, observe the 
bad consequences which may arise from cutting this frenulum, 
and yielding to the obstinate importunity of the nurse. The 
ranine vein or artery which runs near it may be cut, and the 
child will continue sucking and swallowing its own blood ; and 
children have actually died, and the stomach has been found 
distended with blood! But there is another more dreadful 
accident from this cutting of the frenum linguse. A child, says 
Mr. Petit, whose frenum had been cut almost immediately 
after its birth, was suffocated and died five hours afterwards. 
They believed that the operation was the cause of the child’s 
death ; they sent for me to open the body. I put my finger 
into its mouth, and I did not find the point of the tongue, but 
only a mass of flesh which stopped up the passage from the 
mouth into the throat. I cut up the cheeks to the masseter 
muscles, to see what had become of the tongue ; I found it 
turned like a valve upon the fauces, and the point actually 
swallowed into the pharynx. “ Some time after,” continues 
Mr. Petit, “ I was called to the child of Mr. Varin, Sellier du 
Roi, whose frenum they had cut two hours after its birth, and 
who, a little after, had fallen into the same situation with the 
child I have now mentioned, and was nearly suffocated. My 
first care was to introduce my finger: the tongue was not, as 
yet, entirely reversed into the throat. I brought it back into 
the mouth ; in doing which, it made a noise like a piston when 
drawn out of its syringe.” Mr. Petit waited to find the effect 
of its sucking, and, after hearing the action of deglutition for 
some minutes, the child fell into the same state of suffocation. 
Several times he reduced the tongue, and, at last, contrived a 
bandage to preserve it in its place ; but, by the carelessness of 
the nurse, the accident recurred, and the child was suffocated 
during the night. 
CHAP. II. 
OF THE SALIVARY GLANDS. 
The sources of the saliva are very numerous ; the parotid 
glands or superior maxillary gland, and socia parotidis, the in- OF THE SALIVARY GLANDS. 
147 
fierior maxillary or submaxillary glands ; the sublingual glands; 
and (according to the opinion of many) the glandular follicules 
of the root of the tongue: the palate, and even the buccales 
and labiales, or glands of the cheeks and lips, are also to be 
enumerated as sources of saliva. 
The parotid gland, as its name implies, is that which lies 
near to the ear. It is the largest of the salivary glands; and it 
is of much importance for the surgeon to observe its extent 
and connections. A great part of it lies before the ear, and 
betwixt the ear and jaw. It extends over the masseter mus- 
cle, and upward to the zygoma. But there is also a great part 
of it which lies below the tip of the ear, and betwixt the angle 
of the jaw and the mastoid process. Its surface is unequal, 
and composed of little masses or lobules of gland, united by a 
cellular membrane. The duct of this gland was discovered 
by Needam, and afterwards by Steno: it is very often called 
Steno’s duct. When it is injected with quicksilver, the 
branches are seen distributed in a most beautiful and minute 
manner amongst the lobuli of the gland, and similar to the 
branching of veins. These branches have a direction up- 
ward, and unite into a trunk, which passes from the upper 
part of the gland across the cheek over the origin of the mas- 
seter muscle : it then pierces the buccinator muscle, and opens 
upon the inner surface of the cheek, opposite to the second 
dens molaris. This duct has strong white coats; but, although 
the mouth of the duct is very small, the duct itself is dilata- 
ble to a great size, so that tubes of a considerable size have 
slipt into it, and been buried in the body of the gland. 
The socia parotidis is a small gland, (which, however, is 
by no means constant,) seated on the upper side of the duct of 
the parotid gland, and just under the margin of the cheek- 
bone. It opens by a lesser duct into the great duct of Steno. 
Sometimes, however, instead of one considerable gland, there 
are several small ones, seated in the course of the great duct, 
and opening into it by several minute ducts. 
Of the submaxillary and sublingual glands. The 
submaxillary gland is of a regular oval figure ; it lies under the 
platysma myoides on the tendon of the digastric muscle; it is 
defended by the angle of the lower jaw, while it is generally 
connected with or involves the root of the facial artery. It is 
regularly lobulated ; and its duct passes forward between the 
genio-glossus and mylo-hyoideus, and under the sublingual 
gland. The openings of the submaxillary ducts, or ducts ojf 
Wharton, are very easily distinguished. They open under 
the tongue very near each other on each side of the frenum 
linguae; so that they appear as if tied down by the frenum. 148 
OF THE SALIVARY GLANDS. 
When these are excited to discharge their fluids, they become 
a little erected, their patent mouths are seen distinctly, and the 
tortuous course of their canal in the bottom of the mouth may 
be observed. 
The sublingual gland is of a flat and elongated form; it 
lies close under the tongue between the genio-hyo-glossus and 
mylo-hyoideus muscles. It is the smallest of the three great 
salivary glands. The two sublingual glands stretching closely 
under the tongue, they are separated from the mouth only by 
the membrane of the mouth. The duct of the sublingual 
gland opens into the duct of Wharton at the same time that it 
opens by small lateral ducts, with loose pendulous mouths 
upon the lower surface of the tongue. The glandula violciris 
is seated betwixt the masseter and buccinator muscles: it pro- 
perly belongs to the class buccales. 
From the general surface of the lips, tongue, cheek, and pa- 
late, there is a fluid exhaled. This exhaling surface, and all 
those glands, are excited to action by the same stimulus with 
the membrane of the mouth. The saliva moistens the surface 
of the mouth, assists in manducation, and preparing the food 
to be swallowed and acted upon by the stomach, and accele- 
rates digestion. As the mouth is an exhaling surface, so is it 
an imbibing and absorbing surface. Calomel may be rubbed 
upon the mouth so as to salivate. 
CHAP. III. 
VELUM PALATINUM; UVULA; ARCHES OF THE PALATE; 
AND AMYGDALiE. 
The velum pendulum palati is the vascular and fleshy 
membrane, which, hanging from the bones of the palate, di- 
vides the mouth from the fauces. It is not a simple mem- 
brane, but has betwixt its liminae many glands, which open 
upon its surface by little follicules, and is thickened and 
strengthened by muscular fibres: so that it is more of a fleshy 
partition, stretching backward and eking out the palate, than 
a hanging membrane. 
The edge of the velum palati is not square, but turned into 
elegant arches; and, from the middle of the arches of the pa- ARCHES OF THE PALATE. 
149 
late, hangs down the uvula, so named from its resemblance 
to a grape. It is a large, soft and glandular papilla, pecu- 
liarly irritable and moveable, having in it muscular fibres, and 
hanging from the moveable soft palate. It seems to hang as 
a guard over the fauces, and by its sensibility, in a great de- 
gree governs the operation of these parts. It is also part of the 
organ of the voice. 
The arches of the palate or fauces descend on each 
side from the velum palati. They are muscular fibres, covered 
with the soft vascular and follicular membrane of the fauces.* 
There are two on each side. These arches stand at some dis- 
tance from each other, so that the isthmus of the fauces resem- 
bles the double-arched gateway of a citadel, or the arched roof 
of a cathedral, with the uvula hanging as from the central 
union of four semicircular arches. 
Fig. 20. 
Behind the soft palate is the opening of the nose backward 
into the throat. Now, the use of the velum is, that in swal- 
lowing, it may be drawn up like a valve upon the posterior 
opening of the nose ; and there being, at the same time, an 
action cf the arches of the palate, the whole is brought into 
a funnel-like shape, directing the morsel into the pharynx and 
gullet. In this action the direction of the food assists, but, 
in vomiting, the valvular action of the velum is not so accu- 
rate ; and often the nose is assailed with the contents of the 
* See Yo3,1. Constrictar Isthmi faucium and Palato-pharyngeus 150 
AMYGDALjE. 
stomach. The velum also is a principal part of the organ oi 
the voice. 
Amygdala. Betwixt the arches of the palate on each side, 
lies a large oval gland of the si£e and shape of an almond. 
These are the tonsils or amygdalae. The amygdala is a mucous 
gland : it is loosely covered with the investing membrane of 
these parts : its surface is seen, even in‘a living person, to be 
full of large cells like lacunae ; these communicate ; and the 
lesser mouths of the ducts open, into them. On a narrower 
inspection of the amygdala, I describe its structure thus : with- 
in the arch of the palate, and before the arch of the fauces, 
there is a fossa of an oval shape, and on the surface of the 
membrane a number of cells open like the mouths of veins. 
These do not appear to me to communicate. When the 
arches and the amygdala are dissected out behind these holes, 
we feel a gland, as it were one solid body; but on further 
dissection from behind, the cellular membrane being taken 
away, instead of one large giant] there appear a number of 
lesser ones. These glands discharge their secretions into the 
oblique passages which are seen on the membrane of the 
throat, and from these lacunae the mucus is pressed out when 
the morsel is pressed backward. From this naturally loose 
texture, and from its being a vascular and secreting body, ex- 
posed to the immediate vicissitudes of weather, the amygdala 
is often inflamed, and greatly impedes the action of the sur- 
rounding muscular fibres in the action of deglutition. The 
use of the amygdala is evidently to lubricate the passage of 
the throat, and facilitate the swallowing of the morsel: and, 
for this reason, are the mouths of its ducts cellular and irregu- 
lar, that they may retain the mucus until ejected by the action 
of deglutition. In this operation, the amygdalae are assisted 
by numerous lesser glands, which extend all over the arches 
of the palate and pharynx. But these are parts which come 
again to be recapitulated, as introductory to the account of 
the structure of the (esophagus and stomach, in the succeeding 
part of the work. 151 
CHAP. IV. 
OF THE SENSE OF TASTING. 
On the surface of the tongue are to be observed many pa- 
in which the extremities of the gustatory nerve ter- 
minate : they are the seat of the sense of tasting. These 
papillae are in the true skin of the tongue, and are extremely 
vascular. They are covered by the rete mucosum, and a very 
fine cuticle, and, indeed, they have much resemblance to the 
papillae of the skin. These papillae, which are the organs of 
taste, are to be seen on the point and edge of the tongue, and 
consist of a pretty large vascular soft point which projects from 
an opaque and white sheath. If Ave take a pencil and a little 
vinegar, and touch or even rub it strongly on the surface of 
the tongue, where those papillae are not, the sensation only 
of a cold liquid is f$lt: but when you touch one of these pa- 
pillae with the point of the brush, and at the same time apply 
a magnifying glass, it is seen to stand erect and rise conspicu- 
ously from its sheath, and the acid taste is felt to pass as it 
were backward to the root of the tongue. The exquisitely 
sensible papillae are placed only on the point and edge of the 
tongue ; for the middle of the tongue is rough and scabrous, 
not to give the sensation of taste, but to force the sapid juices 
from the morsel, or break- down the solids against the roof of 
the mouth, and assist in their solution. The more delicate 
and vascular papillae would be exposed to injury if situated on 
the middle of the tongue. Before we taste, the substance 
dissolved in the saliva flows over the edges and point of the 
tongue, and then only comes in contact with the organ of 
taste. 
It would appear that every thing, which affects the taste, 
must be soluble in the saliva; for without being dissolved in 
this fluid, it cannot enter readily into the pores and inequali- 
ties of the tongue’s surface. 
A curious circumstance, in the sense of taste, is its subser- 
viency to the act of swallowing. When a morsel is in the 
mouth and the taste is perfect, our enjoyment is not full: there 
follows such a state of excitement in the uvula and fauces, 
that we are irresistibly led to allow the morsel to fall back- 
* Albinus Ann. Acad. lib. i. cap. xv. 152 
OF THE SENSE OF TASTING. 
ward, when the tongue and muscles of the fauces seize upon 
it with a voracious and convulsive grasp, and convey it into 
the stomach. The measure of enjoyment is then full. This 
last short-lived gout is the acme. Were not this appetite of 
the throat and uvula connected with the action which impels 
the food into the stomach, the complete enjoyment of the 
sense of taste alone would satisfy, and would have rendered 
unnecessary the disgusting practice of the Roman Gourmand, 
who forced himself to vomit that he might resume the enjoy- 
ment of eating. But, as it is, the connection of the stomach 
and tongue is such, that the fulness of the stomach precludes 
the further enjoyment of the sense of taste. The senses of 
smelling and taste have their natural appetites or relish; but 
they have also their acquired appetites, or delight in things 
which to unsophisticated nature are disagreeable: so that we 
acquire a liking to snuff, tobacco, spirits, and opium. “ Na- 
ture, indeed, seems studiously to have set bounds to the plea- 
sures and pains we have by these two senses, and to have con- 
fined them within very narrow limits, that we might not place 
any part of our happiness in them ; there being hardly any 
smell or taste so disagreeable that use will not make it tolera- 
ble, and at last, perhaps, agreeable ; nor any so agreeable as 
not to lose its relish by constant use. Neither is there any 
pleasure or pain of these senses which is not introduced or 
followed by some degree of its contrary which nearly balances 
it. So that we may here apply the beautiful allegory of the 
divine Socrates: that although pleasure and pain are contrary 
in their nature, and their faces look different ways, yet Jupi- 
ter hath tied them so together, that he who lays hold of the 
one draws the other along with it.” BOOK V. 
OF THE SKIN AND OF THE SENSE OF TOUCH. 
OF THE SKIN. 
THE skin is divisible, by the art of the anatomist, into four 
laminae or membranes, distinct in texture and appearance, and 
use, viz. the cuticle, or epidermis; the corpus mucosum,or reti- 
cular tissue; the cutis vera, dermis corium, or true skin : but 
from the surface of this last there is separated a vascular mem- 
brane, below which is the surface of the true skin ; lastly, we 
may enumerate the tela cellulosa as constituting a part of the 
general integument. 
The cuticle, or epidermis, or scarf skin, is the most su- 
perficial of these layers : it is a transparent and insensible pel- 
licle which serves, in some degree, to resist the impression of 
external bodies on the surface of the body, and to blunt the 
otherwise too acute sensation of the cutis vera.* In man it is 
very thin, unless in those parts which are exposed to the con- 
tact of hard bodies, as the palms of the hands and soles of the 
feet. The thickness of the cuticle there, however, is not al- 
together the effect of labour and walking, but there is even in 
the early foetus a provision for the defence of the skin of the 
feet, by the supply of a thicker cuticle. When the cuticle is 
drawn from its foot the sole is white, opaque, and thick, whilst, 
in the leg, it is transparent and more delicate.f This is also 
particular, that by labour or continued pressure on the cuticle 
it does not abrade and become thin and tender, but thicker, 
harder, and the part more insensible, so as even to acquire a 
horny hardness and transparency. Of this we have an exam- 
ple in the hands of smiths and other woi'kmen, and in a remark- 
able manner in the feet of those who have been accustomed 
to walk bare-fool on the burning sands. It is thus a protec- 
tion to the foot n a state of nature. But if the skin be too 
much or too quickly exerted, instead of forming additional 
layers of cuticle, a serous fluid is thrown out from the true 
* It is unaccountable that so great a man as Morgagni could suppose the 
cuticle to be the mere effect of air and pressure on the surface of the true 
skin. Adversar. Anatom. III. J3. 
f Albini, Jlnnot. Acad. 
* T V 154 
OF TOUCH AND OF THE SKIN. 
skin, which separates the cuticle in blisters; and this over-ac- 
tion of the skin will throw off the cuticle, as we see to be the 
consequence of the irritation of plasters or cataplasms, scald- 
ing water, exanthematous diseases, erysipelas and mortifica- 
tions, See. When the foot comes to be unnaturally pinched in 
shoes the hard leather works perpetually on a point of the 
toes, and blisters the feet; but if in a lesser degree and longer 
continued it excites the formation of cuticle in the skin below, 
which thrown outward by succeeding layers of cuticle, at last 
forms a corn or clavus, and which, like a small nail, has a 
broad head with a conical point shooting into the tender skin.* 
The cuticle is perforated by the extremities of the perspir- 
ing and absorbing vessels, and by the ducts of the glands of 
the skin, and by the hairs. Indeed, when the small pores of 
the skin or foramina are examined narrowly, the cuticle is seen 
to form sheaths which enter into them, and which, when torn 
out, are like little tubes having a perforated point; for when, 
by maceration, the cuticle is separated from the skin, as we 
draw it off we see little processes of the cuticle, which enter 
into the pores of the skin. 
In the dead body the cuticle may be separated by permit- 
ting putrefaction to go on, and for this purpose, the skin is put 
in maceration :f Ruysch separated it by extending a portion 
of skin and pouring boiling water upon it.| Vesalius and 
Malpighi practised the coarser way of carrying a red hot iron 
near the skin. 
Mr. Cruickshanks enumerates three classes of processes of 
the cuticle: there appear evidently two. The first lines the 
pores through which the hairs pass : these are the longest. 
The second class is easily distinguished on the inside of the cu- 
ticle, which covers the palms of the hands or soles of the feet, 
or indeed on any part of the cuticle ; and they appear in regu- 
lar order on those parts of the cuticle which correspond with 
the parallel or spiral ridges of the cutis: these enter into the 
pores of the true skin. The surface of the cuticle is uniform 
next the skin; but, on the outer surface, it is rough and squa- 
mous. These squamae are the portions of the cuticle, which, 
breaking up, are rubbed off; for there is a perpetual change, 
by the formation of new cuticle under the old, and the abra- 
sion or desquamation of the old surface. 
When I say that the cuticle is uniform I must not forget to 
speak of the regular lines observable on both its surfaces, and 
* De clavo pedis, vide Albinus, Acad. Annot. lib. vi. cap. vi. et vide tab. ii. 
Kg-1- . . 
f Santorini Observ. Anat. cap. i. § i. + De hum. C. fabrica, lib. ii. c. 6. OF TOUCH AND OF THE SKIN. 
155 
which are especially observable on the tips of the fingers, and 
which are a very particular part of the organ of touch. 
The ulcerative process has no power over the cuticle, so 
that when the matter of an abscess has reached the cuticle, its 
progress is stopt until the cuticle is burst by the distention 
This is the reason of the greater pain of abscesses in the soles 
of the feet and palms of the hand, where the cuticle is very 
strong.* 
OF THE STRUCTURE AND GROWTH OF THE NAILS. 
The nails are naturally connected with the cuticle, for 
they remain attached to it; in exanthematous diseases, when 
the cuticle exfoliates, the nails are also pushed off; and in 
death they both separate from the true skin by maceration 
and beginning putrefaction. The nails are to give firmness 
and resistance to the points of the fingers. Although they 
take a very universal adhesion, it is chiefly from the root that 
they grow and shoot out to the point of the fingers, to which 
they adhere firmly. Over the root of the nail the cuticle pro- 
jects, and under it the rete mucosum is extended; and under 
this, and defended by it, are the papillae of the skin. 
Like the cuticle, the nails are without vessels or sensation: 
they are undergoing a perpetual growth, by thin roots, and are 
worn down by labour. When cherished, they grow to an 
amazing length, and curve a little over the points of the fin- 
gers ; and serve in some nations as a most unequivocal sign of 
the person so ornamented being above the necessity of keep- 
ing herself. It was supposed that the nails were formed b)T the 
extremities of the tendons, which extending beyond the flesh 
were dried and hardened ;f and the celebrated Albinus de- 
scribes the nail as formed by the conversion of the papillae 
which lie under itj;: they are generally conceived to be a con- 
tinuation of the epidermis.^ 
But saying that the nails are continuations of the cuticle, 
though true, is saying nothing.—We cannot believe, even on 
the authority of Albinus, that the nervous filaments which lie 
fasciculated under the nail are converted into the nail, merely 
because the under surface of the nail is reticulated like these 
filaments. For.it is evidently reticulated like the soft fila- 
ments, in order to give lodgement to them, to have a corre- 
sponding surface with them. 
* See Hunter on Blood and Inflam, p, 469 
* Annot. Acad. vol. i. lib. ii. cap. iv 
f Riolanus. 
S Winslow 156 
OF TOUCH AND OF THE SKIN. 
The nails differ from the cuticle in not scaling or exfoliating 
like it, but in growing from a root like a hair. 
OF THE HAIRS. 
The hairs grow from a bulbous root, seated in the cellular 
membrane. This bulb is vascular, and has connection, by ves- 
sels, with the cellular texture. It consists of a double mem- 
brane ; the outer is a kind of capsule which surrounds the 
other, and stops at the pore in the skin, and does not form 
part of the hair. Betwixt these capsules, there is a cellular 
tissue, and the space is commonly found filled with a bloody 
fluid. In the bottom of the inner sac, there is a small body, 
called monticule by Duverney, from which the hair is seen to 
arise ; and if this is left when the bulb of the hair is pulled out, 
the hair will be regenerated. 
The root of the hairs, says Winslow, is covered by a strong 
white membrane, which is connected with the skin and cellu- 
lar membrane. Writhin the root, there is a kind of glue, some 
fine filaments of which advance to form the stem, which passes 
through the small extremity of the bulb to the skin. As the 
stem passes through the root, the outer membrane is elongated 
in form of a tube, which closely invests the stem, and is en- 
tirely united with it. And many authors agree, that the hair 
does not perforate the cuticle, but takes from it a vagina which 
accompanies it in all its length.* 
The hair serves as a distinction in the human tribes. The 
European has the longest hair, next to him the Asiatic, then 
the American, and lastty the African.f A common opinion is 
entertained that hair on the body is a mark of strength ; but I 
have observed our famous boxers, when in high condition, are 
smooth, fair, and clear in the complexion of their bodies; 
while men of a dark sallow hue are generally hairy on the 
trunk and shoulders. Betwixt hair and wool, or betwixt the 
hair on different parts of the body, there is no distinction in 
the anatomical structure. In the growth of hair and wool, 
however, there is a difference. They are both produced an- 
nually ; but wool is shed at once and leaves the animal bare, 
whilst the hair falls off gradually, and the young and the old 
hairs are together growing at the same time. Hair is of uni- 
lorm thickness in its whole length ; whereas wool is variable in 
the thickness of its filament;—further it has been found, that 
* Vide quae de hoc Albinus Animadvertit. Acad. Annot. 1. vi. cap. ix. and 
Morgagni Adversar. et Epist. An. iii. §4. 
f Mr. White of Manchester tells he has seen a lady with hair six feet in 
length ;—a Prussian soldier whose hair trailed on the ground. OF TOUCH AND of the skin. 
157 
the thicker part grows during the warmer times of the season ; 
that it is thicker in summer, and finer in the spring and au- 
tumn. This shows us how the fleece becomes coarse and hairv 
in a warm climate. 
RETE MUCOSUM. 
The rete or corpus mucosum, or Reticulum Malpighi, lies 
betwixt the cuticle and the surface of the true skin. It is a 
mucous layer, pervaded by the little fibrillse passing betwixt 
the skin and cuticle. I consider it as a soft bed to envelope 
and preserve the papillae of the skin, and as intended to be- 
come cuticle in due succession. It was considered, by Albi- 
nus, as of a nature adapted to imbibe the fluids through the 
cuticle, and as a production of the epidermis. Mickle be- 
lieved it to be only a mucous fluid, inspissated into the form 
of a membrane; and that it was dissolved by putrefaction, 
while the skin and cuticle remained firm. It is the seat of co- 
lour in the skin, and is of a white transparency in the albino, 
and in the inhabitants of temperate climates. It is black in 
the negro ; copper coloured in the mulatto ; yellow in the 
Egyptian.* It is supposed to preserve the negro from the 
heat of the climate ; but I conceive thatthe power of resisting 
the rays of the sun in warm climates, must be looked for in 
other constitutional peculiarities ; for certainly a surface which 
absorbs the light must produce heat more rapidly than a white 
one, which repels it.f The rete mucosum changes its shades 
of colour in Europeans, from the effect of light; but this tan- 
ning seems to have no strict resemblance to the permanent 
colour of the negro skin. It soon reaches its maximum by 
the influence of the sun, and soon wears off again. And this 
degree of blackness does not attach to the offspring.When 
* Malpighi de sede negridinis in Ethiope. It has appeared to me that there 
was a great deal of colour in the cuticle of the negro, and so Morgagni, “ne- 
gricante et fusco colore infectas.” Adversar. II. Animad. IV. See also Blumen- 
bach de generis humani Varietate. The colour of the skin belongs to tribes, 
and is only in a certain degree affected by climate. Humboldt, Essaie Politique 
sur la Nouvelle Espagne, observes that climate, which has such an effect on 
Europeans, has little or none on the Indian complexion : tribes of a temperate 
climate are darker than those inhabiting a province less cool and temperate. 
The Indians on the tops of the Andes are as dark as the inhabitants of the 
plains. Humboldt also asserts (contrary to Volney) that, in the provinces of 
Spanish America, the children of Indians are copper coloured from the mo - 
ment of their birth. 
f Priestley’s Experiments. 
| The Gradation in Man, by Charles White, of Manchester.—Some have said 
that extreme cold also tans the skin, as the Esquimaux Indians, and Green- 
landers, are dark ; opposed to this, we find the Finlanders and Norwegians fait 
beyond other Europeans. There is much in the habits of life ; a painter will 
not find his carnation tints amongst the poor—nor in the skin of a Highlander ; 
yet where so pure as in a Highland lady ? 158 
or TOUCH AND OF THE SKIN. 
the rete mucosum is destroyed by ulceration, it is imperfectly 
regenerated, and does not possess its former colour. In a ne- 
gro the inner surface of the rete mucosum is blacker than the 
outer surface; the inner surface of the cuticle is softer and 
darker than the outer surface.* Mr. White argues, that if 
this blackness were the effect of the sun, that part most ex- 
posed would be the blackest. But though I agree with him 
in thinking that the blackness of the negro is not owing to cli- 
mate, yet I see this argument of his is incorrect; for it is not 
the direct influence of the sun which tans; no such effect 
comes of exposing dead skin ; it is the excitement of the living 
vascular surface in the formation of new matter, or the dis- 
charge of colouring matter in the rete mucosum. 
While the rete mucosum has its peculiar use of defending the 
delicate surface of the papillae of the skin, I conceive it to be 
undergoing a perpetual change : to be thrown off in succession 
from the vascular surface of the skin, and in its turn to form 
the cuticle by its outer layers. The inner surface of the rete 
mucosum is softer and more pulpy, the outward surface more 
allied to the cuticle, which gives occasion to Mr. Cruickshanks 
to say it is double. 
VASCULAR MEMBRANE OF THE TRUE SKIN. 
Under the rete mucosum, and on the surface of the skin, 
there is a soft vascular membrane, which is still above the po- 
rous and glandular true skin. It was first demonstrated by in- 
jections in subjects who had died of small-pox, and is also so 
much strengthened by other inflammatory actions of the ves- 
sels of the skin, as to be capable of demonstration. It was at 
first supposed that this vascular membrane was the rete mu- 
cosum successfully injected ; but afterwards it was found, that 
this vascular membrane existed independently of this rete mu- 
cosum.| Mr. Cruickshanks conceives that it is cuticle in its 
state of formation, and that the rete mucosum is in fact a cuti- 
cle advancing to the state of perfect maturation. But I should 
rather believe that this is a vascular surface, not changeable, 
nor losing its vascularity, to be thrown off in form of rete mu- 
* Mr. White of Manchester, on the Gradation of Man, in the plate from a 
preparation of Mr. Cruickshanks. For opinions regarding the cause of colour 
in the skin, see Albinus de sede et causa Coloris JElhiopium, Sugd. JJatav. 1737. 
Haller Element. Physiolog. vid. pag. 20.—Blumenbach de generis humani varietate\ 
nativa Getting#, 1795, page 122, and note. 
f Mr. Baynham, who discovered this vascular surface, conceived that he had 
injected the rete mucosum. Ruysch and others mentioned by Albinus, sup- 
posed they had injected the cuticle when most probably they had torn off the 
vascular membrane, or as Albinus alleges, Acad. Annot. lib. vii. c. iii. in tak 
ing off the cuticle they had torn up the vascular papillae along with it. OF TOUCH AND OF THE SKIN. 
159 
cosum : but, in itself, the organized surface, which is to secrete 
the rete mucosum, and which secretion does in succession be- 
come cuticle. This vascular surface of the skin, for such I 
must suppose it, (although it be capable of being separated by 
long maceration and putrefaction, into something like a dis- 
tinct membrane,) is the seat of the small-pox pustule, and pro- 
bably all other cutaneous diseases.* 
Thus there are three laminae above the true skin, distinguish- 
ed by their character; the cuticle, the rete mucosum, and the 
vascular membrane : but as some have divided the rete muco- 
sum into laminae, Mr. Cruickshanks has separated two vascular 
layers from the surface of the skin. They who are fond of such 
minute subdivisions, may thus enumerate five laminae or mem- 
branes, before coming to the porous surface of the true skin. 
OF THE TRUE SKIN. 
The true skin is the dense, elastic, and vascular membrane 
which is under these outer layers already treated of. It con- 
sists of a net-work of firm filaments, having in their protection 
sebaceous glands, exhalent and absorbent vessels, nerves, the 
papillae or organized extremities of the nerves, and the roots of 
the hairs. These are sufficient to give it both some substance 
and firmness. While it has substance, strength, and elasticity 
to defend the body, it is also an organized surface, as important 
in its function, and the healthy action of the system depending 
upon it nearly as closely as on the action of the lungs and sur- 
face of the intestines. 
The skin is dense on the outer surface, while the internal 
layers are loose, and gradually degenerate into the cellular 
substance. Our soldiers and sailors have a way of marking 
their skins with gunpowder or with vermilion, which is inde- 
lible. They prick the skin and insert the colouring matter 
into it, where it remains without producing inflammation, and 
unabsorbed. But this is no proof of the unchangeable nature 
of the skin as regards its colour, or whatever else may distin- 
guish the nations and tribes of man.f 
We have to attend to the pores and villi of the skin: on 
narrowly observing the surface of the skin, we find it irregu- 
larly porous. These are the ducts of sebaceous glands, which 
are lodged in the skin. They transmit the hairs also, and are 
the perspiring, and, probably, the absorbing pores) or, at least. 
* Of the slough of the small-pox pustule, see Dr. Adams’s Morbid Poisons. 
Appendix. 
f I allude to the ingenious essay of the Rev. S. S. Smith, of the American 
Philosoph. Society, on the causes of the variety in the human complexion and 
colour 160 
Of TOUCH AND Of THE SKIN. 
within these larger pores the absorbing and transpiring vessels 
terminate. These pores are most remarkable about the nose, 
mouth, palms of the hands, and soles of the feet. Into these 
pores of the true skin, as we have mentioned, little sheaths of 
the cuticle enter, and through these sheaths the perspiring 
matter must consequently escape : but perspiration is the ac- 
tion of living parts ; in death, the action of the perspiring ves- 
sels ceasing, the pores of the cuticle are no longer pervious to 
the fluids, and there is no perspiration or exudation through 
them ; even when the dead surface is exposed to heat, it dries 
only where the cuticle is off. 
OF THE ORGAN OF TOUCH.* 
The villi of the skin project above its surface, like the pile 
of velvet. They vary much in size, and in some places are 
very much prolonged. They conduct the sensible extremities 
of the cutaneous nerves to form the organ of the sense of 
touching;! I see that these sentient filaments are very vascu- 
lar at their extremities. When the hand is minutely injected, 
and there seems a general blush of redness over it; when the 
cuticle is taken off, and we examine the villi with a powerful 
magnifying glass, their extremities are seen bulbous and red. 
We know that even in nerves there is no sensibility without 
blood be supplied, and I look upon this high degree of vascu- 
larity as a provision for great sensibility. 
These fine filaments are placed in the softest bed possible. 
Examine the minute ridges of the cuticle, and you may dis- 
tinguish them to be quite regular; the ridge which is promi- 
nent external corresponds with a depression or minute sulcus 
within. In these sulci, or in the interstices of the ridges of the 
cuticle, there is a soft matter in which the villi lie secure,'yet 
ready to receive the impression made on the insensible 
cuticle. 
Of the nature of the sensation conveyed by the nerves of the 
sense of touch we are as ignorant as of that conveyed by the 
other nerves. Some are accustomed to consider this as an in- 
ferior sense, for no better reason than that it is more common 
to the surface of the body, whereas it is the most important, 
and that which ministers to the other senses and to our neces- 
sities most of all;—it is the sense necessary to the existence of 
every living creature. 
11 Albrnus Dissertatio de Sede et Caus. Color. iEthiop. Malphigl, et Exercit 
de Tael. Organ. 
f Vide de Papillis Cutis, Albini, Ac. Annot. lib. vi. c. x. and Ruysch. OP TOUCH AND OF THE SKIN. 
161 
Nay more, it is that sense which gives correctness to all the 
others, at least if we are right in attributing so much to the ex- 
ercise of this sense ; as hardness, softness, solidity, figure, ex- 
tension, and motion. If the sense of touch be that change aris- 
ing in the mind from the application of external bodies to the 
skin, then certainly the organ has high exercise, and is of all 
the senses the most valuable. But it appears to me that these 
qualities, of hardness, softness, solidity, figure, extension and 
motion, would be known to us, although we had no nerves in 
our finger ends at all! These qualities belong to what I would 
call the muscular sense, that conception of distance which we 
acquire by moving our body or our members, by pressing upon 
an object and feeling the resistance it occasions. Much might 
be said on this subject, but it is evident that these two senses, 
that of motion or action, and of feeling, must be closely allied 
and mutually useful to each other. 
FUNCTION OF THE SKIN. 
The function of the skin has a very extensive connection 
with the due performance of the internal organs of the animal 
economy. 
The perspired matter from the skin consists principally of 
water and carbon. The carbonic acid produced in the pro- 
cess, is by the union of the carbon with the oxygen of the at- 
mosphere. The perspired fluid holds also in solution several 
salts and recrementitious matter of animal substance. 
Besides the insensible perspiration there is an oily exuda- 
tion from the glands of the skin, which appears to be useful 
in giving pliancy and softness to the scales of the cuticle. This 
oily secretion is copiously secreted in the negro; and it ap- 
pears as a means of protection against the powerful influence 
of the sun, in as much as it prevents the cracking and break- 
ing of the squamae of the cuticle. It preserves the skin soft 
and perspirable. The softness of the negro’s skin is remark- 
able ; and this softness and coolness of the skin is observable 
in all degrees of propinquity to the negro. 
It has been long observed that the surface of the body, im- 
mersed in water, gave out bubbles of air. Lavoisier found 
that thin air precipitated lime water. Cruickshanks, Aber- 
nethy, Jurin, continued these experiments illustrative of this 
function of the skin in giving out carbonic acid; but these 
have, been overthrown by Professor Woodhouse, of Phila- 
delphia, who proved that the air so collected upon the surface 
was attracted from the water, not exhaled by the surface. 162 
OF TOUCH AND OF THE SKIN. 
Nevertheless carbon is discharged by the skin,and the quan- 
tity is found to depend on the vigour of circulation, and of the 
constitution; and when discharged from the skin as I have 
said, the attraction of the oxygen of the atmosphere forms the 
carbonic acid. Thus the function of the skin is brought to 
resemble, in the most essential particular, the function of the 
lungs; and I believe all animal surfaces whatever will be found 
to partake of this function, the discharge of the useless carbon 
from the system. 
The powers of the human system are, in all respects, supe- 
rior to that of brutes; and the provision for the human body 
inhabiting the different climates of the globe, is most particu- 
lar. It has been proved that man, for a short time, can sup- 
port existence in a heat of 260 of Far. It is proved, that 
while he can live in indulgence under the line, he can inhabit 
a country so cold as to drive away the white bear of the polar 
regions. A ship’s crew have wintered in 76 of northern lati- 
tude, and the powers of the living body sustained life while 
spirits and mercury were frozen. 
Although there are experiments by Dr. Fordyce, which 
prove that animals possess a power of resisting heat inde- 
pendent of perspiration, still undoubtedly, the free or checked 
perspiration of the surface is a means of equalizing the tem- 
perature of the body. 
According to the activity of the circulation is the heat of 
the body, and according to the activity of the circulation is 
the perspiration in health. By this perspiration, and the 
change of the perspired fluid unto vapour, the heat of the 
body is carried off. In a cold atmosphere, perspiration 
ceasing, the vital heat is retained; in a warm atmosphere, the 
perspiring action being excited, the heat of the body is pre- 
vented, or rather carried off. 
The authorities are contradictory in regard to the absorption 
by the surface, unaided by friction, abrasion, or ulceration.* 
The more important function of the surface is to be con- 
templated in its effect on the general activitv of the vascular 
system, and in the vicarious action which takes place betwixt 
it, the stomach and intestines, and the kidney and lungs. The 
similarity of function performed in the lungs and by the skin 
would lead us to attend to the injury of the former by the im- 
pression of cold on the surface and the checked perspiration, 
The fact that perspiration is altered in degree by the progress 
of digestion, would lead us to attend to the many occasions in 
* IioIIo on Diabetes, Dr. Currie, Abbe Fontana, Dr. Watson. OF TOUCH AND OF THE SKIN. 
163 
which we see the disorders of the viscera effecting changes on 
the skin ; the imperfection of the'function of perspiration, 
when digestion and the function of the viscera are deranged, 
would lead us not only to mark the symptoms of internal dis- 
ease on the skin, but to take the means of exciting the latter 
as a remedy for the former. In the same manner will the 
secretion of the kidney be influenced by the state of the skin 
and of perspiration : need I add that the health and strength 
of the circulation, and of course the health of all the func- 
tions, is influenced by the excitement of the skin. Some 
practitioners take the stomach, and others the bowels, and 
others the liver, on which they harp continually ; let any one 
take the skin as his object of care, and his practice will have 
equal success, his cases and facts become soon as numerous, 
while his connection with general science will be more inti- 
mate ; and if he introduce his system by showing that health 
is enjoyed when the various functions, Avhich together form the 
animal economy, are perfect, and that one function cannot be 
in health without the whole be also, he will, in my opinion, 
have better claims to public favour than any who have yet 
flourished in it by promulgating doctrines in regard to the 
functions and diseases of individual parts. EXPLANATION OF THE PLATES. 
Explanation of Plate 30 
Fig. t. 
THE eye with the cornea cut away, and the sclerotic coat 
dissected back.* 
a. The optic nerve. 
b. The sclerotic coat dissected back, so as to show the 
vessels and nerves of the choroid coat, 
cc. The ciliary nerves seen piercing the sclerotic coat, and 
passing forward to be distributed to the iris, 
d. A small nerve passing from the same source to the same 
destination, }iut appearing to give off no branches, 
ee. Two of the vorticose. 
f. A point of the sclerotic coat through which the trunk of 
one of the veins had passed. 
g. A lesser venous trunk. 
h. The orbiculus ciliaris of Zinn; the ciliary ligaments of 
others. 
i. The iris. 
k. The straight fibres of the iris. 
l. A circle of fibres or vessels which divide the iris into the 
larger circle k, and the lesser circle m. 
m. This points to the lesser circle of the iris. 
n. The fibres of the lesser circle. 
o. The pupil. 
Fig. 2. 
A dissection of the coats of the eye, as they appeared when 
hung in spirits. 
* See Zinn, Tab. iv. jFip. /. 
Fla -2 T. M 
-’i«-2 ■ 
>’ i g - 4-- 1 
7"’:' y. 3, 
rt0 explanation of the plates. 
165 
a. The OPTIC NERVE. 
b. The sclerotic coat folded back. 
c. The choroid coat hanging by its attachment to the scle- 
rotic coat. 
d. The vessels of the retina’ seen as they appeared sus- 
pended in the fluid ; the medullary part of this coat 
being washed away. 
Explanation of Plate 31. 
Fig. 1. 
The lens covered with its capsule, and minutely injected 
in the fcetus calf. 
A. The ARTERIA CENTRALIS RETINAE. 
b. The fringe remaining with the margin of the lens from 
the attachment of the vessels of the ciliary body. 
Fig. 2. 
This figure shows the attachment of the capsule of the lens 
to the membrana pupillaris, in the foetus calf. 
a. The capsule of the lens very minutely injected ; the lens 
has been allowed to escape, and the membrane hangs 
by its attachment to the membrana pupillaris. 
b. That part of the capsule which covers the forepart of the 
lens ; in which not a vessel is to be seen. 
c. The membrana pupillaris, very minutely injected. 
d. The iris, to the circle of which, the membrana pupillaris 
is seen to be attached, and consequently, to close the 
pupil. 
E. The CILIARY PROCESSES. 
Fig 3. 
The ciliary processes, the iris, and membrana pupil- 
laris, as they appear in the human fcetus of the seventh 
month. 
Fig. 4. 
The appearance of a vessel which took its course across the 
pupil in the full grown fcetus, indicating that the membrana 
pupillaris was still present, although it had become pellucid. 
Fig. 5. 
A section of the optic nerve, to show its great degree of 
vascularity. 
a. The body of the nerve quite red with injection. 
b. The coat of the nerve. 
Explanation of Plate 32. 
Fig. 1. 
The representation of an eye with a cataract, dissected. 166 
explanation oe the plates. 
a. The cornea cut from the sclerotic coat, and hanging by 
a shred. 
B. The SCLEROTIC COAT. 
c. The iris. 
d. The opaque lens or cataract ; it is seen to have form- 
ed an adhesion with the iris. 
Fig. 2. 
This figure represents the effect of couching a soft cataract. 
The needle, instead of depressing the cataract, cut it into 
three pieces. 
aa. The cut edge of the sclerotic coat. 
b. The choroid coat, and ciliary processes. 
c. The cataract adhering to the ciliary processes in three 
distinct pieces. 
Fig. 3. 
This figure represents the place into which the couching 
needle must be introduced. 
a. The pupil seen through the transparent cornea. 
b. The iris. 
c. The needle, with the handle elevated, so as to depress 
the point. 
D. The lens and point of the needle in outline : this repre- 
sents the position of the lens when depressed : to com- 
plete the operation, it must be carried a little back be- 
fore withdrawing the needle. 
Fig. 4. 
A scheme, showing the bad effect of introducing the needle 
near the margin of the cornea. 
a. The VITREOUS IIUMOUR. 
b. The LENS. 
cc. The ciliary body ; on the lower part torn by the needle. 
dd. The iris. 
e. The anterior chamber of the aqueous humour. 
Fig. 5. 
Shows the situation of the cataract when depressed. 
a. The anterior chamber of the aqueous humour. 
b. The posterior chamber of the aqueous humour. 
c. The iris. 
d. The vitreous humour occupying the seat of the lens. 
e. The depressed lens or cataract. 
Explanation of plate 33. 
Showing some varieties in the structure of the ear in the 
lower animals. 
Fig. 1. 
The ear of the lobster. T 52 
Vo l. 111. 
Pig’.l. 
Fig.2 
.1*i g. 3. 
;g. i 
ri?-5' 
;n*H .<V' mm. 
H , )J 
Fi< . \ 
Fig.i. 
Fig. 2. 
Fig. 8. 
t'uj. 3. 
Fig. 3. 
Fig. 6. 
I . ' . // del1 
JLency fcf EXPLANATION OF THE PLATES. 
167 
a. The membrane which covers the projecting m ouh of the 
shell containing the organ of hearing. 
B. A transparent pulp or vesicle, upon the bottom of which the 
web of the nerve is expanded. 
c. The inside of the shell containing the organ, which is, of 
course, represented broken open. 
Fig. 2. 
This represents a little bone which is suspended in contact 
with the pulp of the nerve, and which is seen but imperfectly 
in the first figure. 
a. The bone. 
b. An elastic membranous, or rather cartilaginous substance, 
by which the bone is suspended. 
Fig. 3. 
The head of a haddock, with the bones broken up, to show 
the brain and'semicircular canals. 
a. The BRAIN. 
B. The SEMICIRCULAR CANALS. 
* Fig. 4. 
The organ of hearing taken out and displayed. 
a. The sacculus vestibuli. 
b. The bony concretion which lies within, and which, by its 
vibration, increases the impulse. 
c. The auditory nerve passing to be distributed on the sac- 
culus vestibuli, and the extremities of the semicircular 
canals. 
D. D. D. The SEMICIRCULAR CANALS. 
e. One of the extremities of the semicircular canals, in which 
the branch of the nerve is seen to be expanded. 
F.* A lesser division of the auditory nerve. 
Fig. 5. 
The head of a frog with the skin taken off: and we now see 
the cavity of the tympanum in this animal, over which the com- 
mon integuments of the head spread tense, so as to answer the 
purpose of the membrana tympani. 
a. The point of a little elastic bone which is attached behind 
the tense integuments, and receives their vibration. Its 
further connections are seen in the next figure. 
Fig. 6. 
A magnified view of the internal structure of the frog’s ear. 
a. The first bone, which is attached to the skin. 
B. The second bone, which has its inner extremity enlifrged so 
as to fill up the foramen ovale, which leads into the inner 
cavity of the ear. 
c. The great inner cavity of the ear of this animal, answering 
to the vestibule of the more perfect structure. 168 
explanation of the plates. 
d. A chalky concretion which lies within this cavity. 
Fig. 7. 
The head of a serpent. 
a. A bone connected with the lower jaw. 
B. A bone which passes from the integuments (behind the 
large bone a) to the opening into the cavity of the ear, and 
which, of course, receives and conveys the vibration of 
sound into the cavity which contains the expanded nerve. 
Fig. 8. 
The head of the land tortoise, 
a. A large scale which serves the use of the membrana 
tympani. 
;b. A single bone which is seen to pass through the cavity of 
the tympanum ; it is attached by an elastic brush of fibres 
to the scale a, and is enlarged to a head upon its inner 
extremity. This, filling up the foramen of the inner 
cavity, conveys the vibration. 
Explanation of Plate 34. 
In this plate, the anatomy of the bones of the human ear is 
explained. 
Fig. 1. 
We have here the bones which form the chain betwixt the 
membrane of the tympanum and the membrane of the fora- 
men ovale. 
A. The MALLEUS. 
B. The incus. 
c. The stapes. 
d. The os orbiculare, which forms the articulation betwixt 
the incus and stapes. 
Fig. 2. 
In this figure we have a view of the inside of the temporal 
bone, the petrous portion being broken away : we see the 
cavity of the tympanum, the membrane of the tympanum, and 
the chain of bones. 
a. The groove for the lodgment of the lateral sinus. 
b. The hole in the sphenoid for the passage of the artery 
of the dura mater. 
c. The petrous portion of the temporal bone. 
d. The irregular cavity of the tympanum laid open by the 
breaking off of the petrous part of the temporal bone. 
e. The membrane of the tympanum closing the bottom of 
the meatus auditorius externus. 
t. The malleus, the long handle of which is seen to be at- 
tached to the membrane of the tympanum e. 
g. The incus, united to the great head of the malleus r. I.J -V 
ol. Ill 
Fig. 2. 
gig. 1. 
Fg 4. 
Fig. 3. 
.Fu: . *5. 
Z/pwrv /r? 
Mi M* Vol.m. 
P.:JJ 
lr>3’ 
Fig- ‘l. 
Bill 'M‘ 
Len/y /c ? EXPLANATION OF THE PLATES. 
169 
H. The stapes, which is seen to be articulated with the long 
extremity of the incus through the intervention of the os 
orbiculara. 
Fig. 3. 
Shows the division of the temporal bone into the squamous 
and petrous portions. 
a. The squAMOUs part of the temporal bone. 
jb. The circular ring, which forms the meatus auditorius 
externus in the child. 
c. The zygomatic process. 
d. Cells which afterwards enlarge into those of the mastoid 
process. 
Fig. 4. 
The petrous portion of the bone, with a view of the tympa- 
num. 
a. The cavity of the tympanum. 
b. Mastoid cells. 
d. The foramen ovale, into which the stapes (see fig. 1. c. 
and fig. 2. h.) is lodged. 
e. The more irregular opening of the foramen rotundum. 
Fig. 5. 
Represents the labyrinth of the human ear, with the solid 
bone which surrounds it cut away. 
a. The foramen ovale. 
b. The three semicircular canals. 
d. The COCHLEA. 
e. The tube which conducts the portio dura of the seventh 
pair through the temporal bone. 
Fig. 6. 
Explains the manner in which the lamina spiralis divides the 
cochlea into two scalse, and the opening of the one scala into 
the common cavity of the vestibule, and the termination of the 
other in the foramen rotundum. 
a. The bone broken so as to show the cavity of the tympa- 
num. 
B. The FORAMEN OVALE. 
c. Cellular structure of the bone. 
D. The FORAMEN ROTUNDUM. 
e. One of the scalse of the cochlea which is seen to termi- 
nate in the foramen rotundum. 
f. The other scala, which is seen to communicate with the 
vestibule. 
Explanation of Plate 35. 
These two figures are taken from the beautiful plates of the 170 
explanation of the plates. 
Professor Scarpa, and illustrate the soft parts contained within 
the osseous labyrinth, and the distribution of the nerves. 
Fig. 1. 
There is seen the membranous semicircular canals, their 
common belly, and the distribution of the acaustic or auditory 
nerve. 
a. The ampulla of the superior membranous semicircular 
canal. 
b. The superior membranous semicircular canal. 
c. The ampulla of the external membranous canal. 
d. The other extremity of the external canal. 
e. The ampulla of the posterior membranous semicircular 
canal. 
f. The POSTERIOR SEMICIRCULAR CANAL. 
g. The common canal of the superior and posterior canal. 
h h. The sac common to the membranous semicircular canals. 
viz. the alveus communis. 
i. The body or trunk of the acaustic nerve. 
k. The larger branch of the nerve. 
l. A filament of the nerve to the sacculus vestibuli. 
m. The lesser branch of the acaustiq nerve. 
n. A filament to the cochlea. 
o o. Filaments of the larger branch of the acaustic nerve to 
the ampullae of the superior and exterior semicircular 
canals. 
р. The expansion of the nerve on the common alveus, 
q q. Nervus communicans faciei or portia dura. 
r. The beginning of the spiral lamina of the cochlea. 
s. The osseous canal of the nerve, which forms part of the fo- 
ramen auditorius interims. 
t. The cochlea. 
Fig. 2. 
The distribution of the nerve in the cochlea seen by a sec- 
tion of the internal auditory canal and cochlea. 
a. The superior osseous semicircular canal. 
b. The posterior osseous semicircular canal. 
с. The external osseous semicircular canal. 
d. The bottom of the great foramen auditorium internum 
e. The trunk of the great acaustic nerve. 
f. The anterior fasciculus of the acaustic nerve. 
g. A plexiform twisting in the anterior fasciculus of the nerve 
h. A ganglitorm swelling of the nerve. 
i. The greater branch of the anterior fasciculus. 
k. The lesser branch. 
l. A filament of the anterior fasciculus to the hemispherical 
vesicle of the vestibule. EXPLANATION OF THE PLATES. 
171 
in. A branch to the beginning of the lamina spiralis. 
n. The posterior fasciculus of the acaustic nerve. 
o. The filaments about to enter the tractus spiralis foraminu- 
losus. 
p. These nerves seen upon the modiolus. 
q q. The filaments of the nerve passing forward betwixt the 
two planes of the lamina spiralis, 
r r. Their termination on the soft part of the lamina spiralis, 
s. The nerves expanded on the second gyrus of the modiolus, 
t t, u. u. Their further distribution on the lamina spiralis. 
VV. The INFUNDIBULUM. 
x y. The last turn and termination of the lamina spiralis in the 
infundibulum. THE 
OF THE 
VISCERA OF THE ABDOMEN. 
INTRODUCTION. 
VIEW OF THE SYSTEM OF THE VISCERA, AND OF THE 
STRUCTURE OF GLANDS. 
IN this last division of the work we have to comprehend the 
anatomy and functions of the several viscera of the abdomen 
and pelvis: we must consider them not only as individual parts, 
hut as connected together, and as forming with the lymphatic 
and circulating systems of vessels a great part of that chain of 
mutual dependence and relation which constitutes the animal 
economy a whole. It becomes necessary, therefore, to take 
here a general and cursory view of the economy of the intes- 
tinal canal and absorbing system, including at the same time 
something of the history of opinions regarding secretion and 
the structure of glands. It will be understood, that these in- 
troductory observations are meant only to combine the several 
parts, and to prevent that manner of description, which is 
necessary to accuracy and minuteness, from leading us to con- 
sider the several parts as distinct and insulated. 
An animal body is never for a moment stationary: the re- 
motest part is in action, and is suffering a perpetual change. 
From the first moment of our existence we have commenced 
a revolution: we, by slow degrees, advance in activity and 
strength, and ripen to maturity: but by as slow and as sure 
gradations we decline to feebleness and infirmities; and the 
more rapidly that animals advance in the first stage of their 
progress, so is their decline proportioned. 174 
INTRODUCTION. 
But it is not in observing the changes of the animal body 
from youth to age that the operations of the economy appear 
the most interesting. It is when we find the' living body, to 
consist of parts performing a variety of functions, and these 
connected and mutually dependent; when we see the circulat- 
ing fluid throwing out fluid and solid secretions to build up 
and support the body, which is in incessant and daily decay. 
Again, our admiration must be strongly excited when we ob- 
serve the system to consist of fluids and solids, and the exist- 
ence of the animal to depend upon the balance of their power; 
the fluids separating and combining in new affinities, and form- 
ing the various secretions ; and the solids having action, and 
that action controlling the affinities and new combinations of 
the circulating fluids. We find that life subsists by the due 
action of solids and fluids : or that an incomprehensible influ- 
ence in a living bqdy is exerted on the latter, and that the 
chemist can never so combine the fluids out of the body as to 
imitate the changes produced in a living system of fluids and 
vessels. Forgetting that animation is the essential character 
of living bodies, that it influences the chemical affinities, and 
varies the attraction of particles, physiologists have too much 
endeavoured to explain the phenomena of animated nature by 
illustrations formally drawn from mechanics, and hydraulics, 
and in the present day from chemistry. 
In a body in which there is life, there is a perpetual waste; 
first by secretions, which for particular purposes are thrown 
into the cavities, and afterwards carried out of the body en- 
tirely, by the excretions of the kidney, by the perspiration 
from the surface, the exhalation by the lungs, the secretions of 
the intestines. But more than this, there is a decomposition 
of the solids of the body which are carried into the circulating 
fluids, and finally dismissed from the system. Lastly, we can- 
not but observe, that even the powers of muscular motion, nay, 
the powers of the mind and of the senses, are exhausted by 
exercise, and renovated through the influence of the circulation. 
The continued action of a muscle is followed by feebleness, 
and the continued impression of the rays of light exhausts the 
retina, so that the object becomes first faint and then vanishes. 
Since there is waste of the solids and fluids, and exhaustion 
of the energies of the system, so also must there be a source of 
supply, and means of renewing its activity, and there must be 
a perpetual motion in the particles of the living frame. Ac- 
cordingly, animals have appetites requiring the supply of food 
and drink, and the call of hunger and thirst stand in relation 
to the necessities of the body. When food is received into 
the first passages, there is thrown out from the stomach a fluid SYSTEM 6F THE VISCERA. 
175 
which dissolves it, changes its properties, and is itself essen- 
tially altered. The work of assimilation is thus begun. As 
this converted fluid takes its course through the intestines, it is 
more and more changed ; more assimilated to the nature of the 
peculiar fluids of the animal; and having still additional secre- 
tions united to it, particularly the bile, it is by these means se- 
parated from the grosser parts of the aliment. This fluid, 
which is now called chyle, is absorbed by a particular and ap- 
propriate system of vessels, which, from their conveying this 
white and milky-like fluid, are called the lacteals. The lac- 
teal vessels carry the chyle to the thoracic trunk of 
the absorbing system ; but not directly ; for the chyle is depo- 
sited in the mesenteric glands, from which it is again absorbed 
and carried forward. Or if we suppose these glands to be 
merely convoluted vessels, its flow is at least delayed, so that 
it is not at once thrown into the mass of circulating fluids. 
We find then that the stomach performs digestion, and the 
spleen, we will venture to affirm, is subservient to it. The se- 
cretion of the liver we find to prepare the chyle for absorption, 
while at the same time it is the peculiar stimulus to the intes- 
tines. The pancreas pours out a fluid which tempers the acrid 
bile. The superior part of the intestinal canal absorbs the nu- 
tritious fluid or chyle, while the gross remains of the food move 
on to be deposited in the great intestines. The great intestines 
are not only receptacles, but form at the same time an exten- 
sive secreting surface useful in the economy, by throwing off 
the waste of the system. 
The lacteal vessels, which take up the chyle, are but branches 
of the system of absorbents—which is a system consisting of 
two great divisions, the lacteals and lymphatics : the first re- 
ceiving the nutritious fluids from the intestinal canal, and the 
latter being absorbents, taking up the fluids which have been 
thrown out upon the cavities and surfaces of the body ; and we 
presume upon their absorbing the solid parts of the body also. 
Thus the new fluids, rich in supplies, are mingled with those 
which are fraught with the waste and decomposition of the 
system. The thoracic duct, the trunk of this system, conveys 
these fluids thus mingled together into the right side of the 
heart, where they are received into the vortex of the circulat- 
ing red blood. These fluids, now agitated and wrought up 
with the blood in the cavities of the heart, are sent through 
the circulation of the lungs, and submitted to the influence ot 
their action and the exposure to the atmospheric air. 
When chyle is formed in the stomach and intestines, it 
is observed to consist of albumen, serum, globules, and salts : 
but the change which it may undergo by its reception into the 176 
INTRODUCTION. 
lacteals, its being deposited in their glands, its mingling with 
the lymph, its agitation in the heart, have not been observed, 
though it is natural to suppose that by degrees it assimilates in 
its nature to that of the circulating blood, and does at last be- 
come perfectly similar by the operation of the lungs. 
By the exposure of the circulating fluids to the atmosphere 
in the lungs, the carbon of the blood is thrown off, and the 
blood, resuming its purity, is again suited to circulate in the 
body. 
That the blood of an animal has properties which distin- 
guish it from mere matter we readily allow ; but to say that it 
possesses life is to use a term in which few will acquiesce. It 
possesses properties while circulating in the vessels distinct 
from those which it shows out of the body ; and these do not 
depend on the agitation and incessant motion, nor on the de- 
gree of heat, nor on any similar circumstance, but apparently 
on some secret influence which the vessels exert over it. The 
analysis of the blood by the chemists holds out to us little hope 
of advancing in the knowledge of the economy of a living ani- 
mal. Chemistry, when applied to the analysis of animal mat- 
ter, leaves its devotees in a perplexity of knowledge and dis- 
coveries which have no end, and which point to no conclusion. 
There are produced from the blood a variety of fluids by 
organs which are called glands, and the formation or separation 
of these fluids is secretion. But the solid parts of the body 
ought to be considered as secretions equally with the matter 
which flows from the ducts of glands. For there is formed 
and deposited from the blood, during the round of its circula- 
tion, bone to support the incumbent weight of the body ; mus- 
cular fibre, to give it motion; as well as all the other variety 
of solids and fluids. The only difference betwixt these solid 
depositions from the blood and the glandular secretions is, that 
the former are still within the influence of the vascular system, 
and that they are decomposed and re-absorbed, conveyed again 
into the mass of circulating fluids before they can be finally 
expelled from the body. 
The chemists have observed the division of animal bodies 
into solids and fluids, but the subdivisions of these are very in- 
accurate. The fluids they have distinguished into three classes; 
1st, Recrementitious humours, which go to nourish and 
support the body: 2dly, The excrementitious fluids, which 
are carried out of the body by certain emunctuaries ; and the 
3d are of a compound nature, being partly recrementitious and 
partly excrementitious. We must observe, however, that the 
fluids enumerated under these heads show it to be a very incor- 
rect arrangement. The first division comprehends the fat, the SYSTEM OF THE VISCERA. 
177 
mar row, the matter of internal perspiration, and the osseous 
juice. The second comprehends the fluids of insensible tran- 
spiration, the sweat, mucus, cerumen, urine, faeces. And the 
last division comprehends the saliva, the tears, the bile, the 
pancreatic juice, the gastric and the intestinal juice, the milk, 
and the seminal fluid. To attend to their arrangements of 
the solid parts of animals would be equally remote from serv- 
ing any useful end ; for they have thrown together parts so 
discordant in function and so unlike in structure that they can 
be of no use in a general view of the economy, and cannot in 
chemical analysis show a uniform result.* 
Perhaps all the correctness to which we can at present pre- 
tend is some such division as this. Besides forming the 
solid mass of the animal body, these secretions are drawn from 
the blood; fluids which are subservient to the assimilating of 
new matter to the system ; fluids which are useful in preserving 
the mobility of parts ; and, lastly, the secretions which convey 
away the waste and debris of the body, which is successively 
replaced by the apposition of new matter. 
'From this short view of the system we understand how in- 
cessantly the powers are spent in action, and the fluids ex- 
hausted by deposition and secretion, and how essential to life 
the functions of those parts are which act upon and assimilate 
the food. It is the consideration of these parts which forms 
the subject of the first section of what remains of the present 
volume. As in the consideration of these functions the struc- 
ture of the glandular organs becomes a chief subject of inqui- 
ry, it will be natural at present to consider in a general way 
the opinions which have been entertained regarding their 
structure. 
The peculiar nature of that organization by which the seve- 
ral secretions are formed, has hitherto eluded absolute proof 
by experiment or dissection. It is imagined that there are 
some organs which do little more than separate the parts of 
the blood like to the exudation by exhaling arteries. But 
neither in the exhalent arteries, nor in the simple organs, can I 
imagine a simple straining of the blood, but rather that the' 
same principle of activity influences all, and that the several 
varieties ol secretion depend upon an action modified by the, 
living property in the secreting part. It would appear that the 
fluids in circulation and the vessels containing them must re- 
ciprocally affect each other: we know that a change on the 
state of the circulating fluids will alter the nature of the glan- 
dular action, and an excitement of the gland will still more 
* See Fourcroy’s Analysis of Animal Substances. 178 
INTRODUCTION. 
powerfully change the nature of the secretion; the active 
power of the solids appearing to be an agent which controls 
and directs the chemical affinities. 
The term gland is applied to certain solid and firm bodies, 
with regular and smooth surfaces, which are in great number 
over the whole body. The functions of many of these bodies 
are known. They are found to have ducts which convey from 
them a secreted fluid ; but in many of them we discover no 
duct, and can but obscurely guess at their use. 
We are struck with the variety of form in the secreting or- 
gans. We see a simple surface pouring out its fluids; or a 
simple canal into which the arteries throw out the secretion. 
Wre find again the secreting vessels and their ducts convoluted 
and massed together, forming such glandular bodies as I have 
just mentioned ; of which kind are the solid abdominal viscera. 
In the glandular viscera there are greater varieties in form 
than in any of the other parts of the body ; and writh these va- 
riations there is no corresponding change of function. I am 
of opinion that the forms of the solid abdominal viscera result 
entirely from their situation. The liver is convex upwards, 
because the diaphragm is concave ; and it is irregularly con- 
cave downwards, because in contact with the duodenum, colon, 
and gall-bladder. The same may be said of the spleen, the 
.pancreas, the kidney: their form has reference to place, and 
has nothing further to do with their functions. 
When we dissect the glands we do not find them to have a 
similarity in structure. Thus the substance of the liver, the 
kidney, the testicle, &c. are quite unlike, and as their secretions 
are diffex-ent, so ax e their sympathies : the effect of disease upon 
them, and the consequences of medicine operating through 
the general circulation, will be to attach to one individually, 
leaving the others in their accustomed action. There is also 
a very remarkable difference in the length, size, and form of 
blood-vessels passing into the glands. 
In considering the opinions of physiologists or anatomists re- 
garding glandular secretion, and the structui'e of glands, we 
find in the first instance that the old physicians contented them- 
selves with saying that the glands or yiscei'a possessed a pecu- 
liar power to select and separate the fluids from the blood. 
The next class had recourse to hypothesis ; they spoke of the 
separation of certain parts by means of fermentation,* or by a 
kind of filtering through the pores or vessels of glands ; that 
these pores allowed only pai'ticles of a particular size or figure 
* Van Helmont. Vieussens, &c. SYSTEM OF THE VISCERA. 
179 
to pass them.* It was opposed to this hypothesis, that the thin- 
ner fluids must have run through the organs destined for the 
grosser secretions. But when a theory such as this is re- 
ceived, no argument nor proof seems necessary to overthrow 
it. Resting upon authority alone, it stood until it was over- 
turned by the fashion of new doctrines: one equally puerile 
was raised upon its overthrow. 
We observe, says the founder of this theory,! that wet or 
oiled paper will only transmit fluid of that kind with which it 
is previously imbued, it will not transmit the oil when wetted, 
nor will the water make any impression on the paper when 
previously oiled. Upon these facts are to be raised a theory 
of secretion ! Betwixt the secreting vessels and the ducts, in 
the peculiar tissue of which glandular structure consists, there 
is interposed a fluid of that particular kind which is required to 
be secreted, and when the blood is driven against this tissue so 
imbued, no fluid but of nature resembling that already depo- 
sited can be transmitted. By this hypothesis they explained 
secretion, making it to depend on the attraction and repulsion 
of the particles of the blood by fluids previously secreted. We 
may surelv leave this class of physiologists accounting for the 
original depositation of the fluids in the glands without a wish 
to search with them further into this mystery. Commentators 
on this theory, by taking into the system the action of the 
nerves, indicated that they did not altogether forget that the 
body was alive.! 
Another set of physiologists attributed the whole effect of 
secretion to the velocity of the blood in the glands or secreting 
vessels ;§ others, to the length and curves of the vessels, and 
their action upon the fluids. Again, others have been satisfied 
with the round assertion, that the vital action was the essential 
cause of secretion. This, it ought to be understood, must be 
universally acquiesced in, while yet there may remain an in- 
quiry as to the structure and means employed. Disappointed 
in obtaining an unexceptionable general theory of secretion, 
we are only enabled to conclude, that while a power exists in 
an animal body, directing its actions, perhaps both in the solids 
and fluids, and particularly in the mutual influence which they 
exert, the form, length, and activity of the vessels and ducts 
give opportunity to the greater or less degree of intricacy in 
the operation of the principles upon which the secretion de- 
pends. 
Let us then attend to the observations of anatomists, and to 
* Charleton, Descartes, Borelli, Verheyn, &c. &c. f Winslow. Helvetius- 
t Conor, Tentamen epistolare tie Secretione. §Boerhaave, Pitcarne, &c. 180 
INTRODUCTION. 
the appearance which the glandular viscera present under 
the knife. 
It is not perfectly clear what the older anatomists meant by 
the expression Parenchyma. It would appear however to 
have saved them the trouble of investigation. They meant 
flesh, vet not muscular substance, but such as the liver pre- 
sents. This matter they seem to have conceived to be form- 
ed by the blood. Thus Highmore describes the liver to be 
formed of the blood of the umbilical vein : the opinion origi- 
nally of Erasistratus. 
Previous to the time of Malpighi it is fruitless to trace the 
opinion of anatomists regarding the structure of glands. He 
was the first who sought to throw light upon this obscure sub- 
ject by anatomical investigation, and he made a more rapid 
progress than has been done by any man since his day. If we 
take into consideration the difficulties he had to encounter in 
a new field, and the prejudices of the learned with which he 
had to combat, his merits will be found greater than even those 
of Ruysch. The opinions of Malpighi were received by those 
who, forsaking the authorities of names, saw the importance of 
the study of anatomy. Ruysch himself gave credit to the 
opinions of Malpighi in the early part of his life. But Ruysch’s 
more attentive observations being in contradiction to those of 
Malpighi, his maturer judgment rejected that anatomist’s proofs, 
and with a boldness in which he was never remarkably defi- 
cient he invented a new theory, or at least alleged new facts, 
and swayed men’s opinions with an absolute authority. 
Malpighi was an Italian, and born near to Bologna. Whilst 
yet a young man, being sunk under the accumulation of family 
distress, absorbed in grief, and lost to the consideration of his 
interest, he received comfort and assistance from his master, 
who urged him to embrace the medical profession. His pro- 
gress was rapid. After studying at Padua, he was called to fill 
one of the chairs in Bologna. He was then solicited by Fer- 
dinand II., Duke of Tuscany, to be professor in the uni- 
versity of Pisa. Here he was associated with liberal men: 
and now only in his sec ond professorship did he learn to de- 
spise the scholastic learning of the time, and betook himself to 
experiment as the only means by which philosophy could be 
raised from the oppressive barbarism of the schools. Mal- 
pighi and Borelli were associated ; they dissected together; 
they suggested thoughts to each other ; they doubted, and can- 
vassed freely each other’s opinion ; and were to each other an 
excitement and encouragement to perseverance and industry. 
They were supported by government; popular in their teach- 
ing ; while thev collected round them the learned men of the SYSTEM OF THE VISCERA. 
181 
time. This was the origin of the famous Academy del Ci- 
mento. Malpighi was, after this, professor in Messene, and 
died in the Quirinal palace at Rome, of a stroke of the apo- 
plexy,* after having been some time physician to Pope Inno- 
cent XII. Malpighi had many enemies, and even some of his 
colleagues were animated against him with a dishonourable 
jealousy. Many laughed at his studies and occupations as fri- 
volous and absurd. Something must be allowed/or men who 
had laboured with diligence to become learned; for these, his 
opponents, had passed their lives in the study of the Arabian 
writers. With them studies were enforced which held science 
in subjection; studies which, in place of invigorating, served 
only to chill and paralize exertion, and retard ingenious in- 
vestigation. Even Borelli, but from other motives, opposed 
and censured some of the dissertations of Malpighi. 
Malpighi has been considered as the inventor of this depart- 
ment of anatomy, which the French, curious in distinctions, 
have called the analytic method. He showed the impropriety 
of the term Parenchyma, as applied to the substance of glands. 
He proved that the lungs, for example, (which they also called 
Parenchymatous,) were not fleshy, and had no resemblance to 
the glandular viscera of the abdomen. He taught, that though 
glands are smooth on their outer surface, they consist of lo- 
bules connected by cellular membrane; and, upon a still more 
minute investigation, that they consist of innumerable little 
follicules or sacs ; that these are interposed betwixt the arte- 
ries which convey the fluids and the excretory ducts going out 
from them; that the arteries, or the vasa eflerentia, after rami- 
fying and encircling these bodies, pierce them and secrete the 
fluids into them. On other occasions he describes these little 
glandular bodies as appended to the ramifications of the arte- 
ries, like fruit hanging by the branches of a tree. 
Malpighi threw in his liquid injections: dissected and ex- 
amined with the microscope; made careful observations and 
experiments on living animals; and, lastly, attended in a par- 
ticular manner to the phenomena of disease. By disease, no 
doubt, parts swell out and are magnified, and become dis- 
tinpt; but it is not a test of the natural structure, or impli- 
citly to be trusted to. 
•* Much coagulated blood was found in the ventricles of his brain by Baglivi 182 
INTRODUCTION. 
Scheme of Malpighi’s opinion. 
Fig.i. 
Fig. 1. Boerhaave’s plan of Malpighi’s doctrine, a a a 
folliculos glandularum simplicissimarum denotat. b b b singu- 
laria emissaria cuique utriculo a, propri atque in communem 
canalem excretorium r/,c, suos humores demittentia qui tandem 
per hujus aperturam c, emittantur. 
Fig. 2. is a scheme farther to elucidate the opinions of Mal- 
pighi. A, an artery entering the portion of a viscus. B, the 
returning veins. C, the branch of communication betwixt the 
artery and vein which serves to circulate the blood, and con- 
vey a part into the veins. D, another division of the artery, 
which after various playful meanderings, terminates in the 
follicule or little glandular bag, E. F, the ducts which receive 
the secreted fluid from the follicules. 
Ruysch studied at Leyden, under Van Horne, and at a very 
early age attached himself to anatomy and botany. At this 
time he brought himself into notice by a defence of the pro- 
fessors against one Bilsius, who, although he was learned and 
acute, had attacked them with all the weapons of a Charlatan. 
Returning to his native country, he was raised to the profes- 
sorship of anatomy and botany in Amsterdam. It was here 
that Ruysch made those discoveries in anatomy, and that won- 
derful and sudden progress in practical anatomy, which not 
only raised him above his cotemporaries, but has been the 
admiration of all since his time. Though new and various 
methods of preparing the body have been discovered since the 
time of Ruysch, yet there has been no approach to the ele- 
gance with which he displayed the structure of minute parts. 
It has been said that, while others preserved the horrid fea- 
tures of death, Ruysch preserved the human body in the soft- 
ness and freshness of life, even to the expression of the fea- 
tures. We must no doubt ascribe some part of this encomium 
to the exaggeration naturally arising from the novelty of the 
thing. But as to his superiority in the manner of displaying 
the minute vessels of delicate parts, and his methods of pre- SYSTEM OF THE VISCERA. 
183 
serving the parts in liquors, transparent and soft, and so as to 
float in their natural folds, there can be no doubt. Neither 
can the minuteness and success of his injections be denied: 
we have too many occasions in which we must resort to the 
catalogue of Ruysch’s museum for the true anatomy, to doubt 
his great success, or to question the truth of those encomiums 
which have been bestowed upon him. 
Kings, princes, ambassadors, and great generals, but more 
than these, all the learned men of the time, crowded to the 
museum of Ruysch. We must not blame him if, whilst others 
were merely speculating about the structure of parts, he, sur- 
rounded by so princely a museum, should simply have laid 
open his cabinets, and bid them satisfy themselves whether or 
not he was right. Ruysch’s preparations went to contradict 
the opinions of Malpighi. His injections pushed more 
minutely, showed those round bodies which are to be seen 
in some of the glandular viscera (and which Malpighi took to 
be little bags into which the secreted fluid was poured) to be 
merely convoluted arteries. Ruysch taught, that the minute 
arteries, after making these convolutions, terminated in the be- 
ginning of excretory ducts ; that there was no substance or 
apparatus interposed, but that the vessels and ducts were con- 
tinuous. His opinions being formed upon the strength of more 
minute preparations, and a superior /dexterity of anatomical 
investigation, few anatomists chose to be outdone, or to 
acknowledge that they could not see what he saw. This I 
believe to be one reason of the rapid progress of Ruysch’s 
opinion. 
Sc/ieme of Ruvsch’s opinion. 
i 1 The smaller arteries which do not enter into folli- 
cules, but are convoluted. 2 2 The appearance of bodies or 
bags, but which are merely owing to the convolutions and tor- 
tuous figure of the arteries before,they terminate in the excre- 184 
INTRODUCTION. 
tory ducts. 3 3 Excretory ducts or vessels lorrned by the 
continued extreme branches of the arteries.* 
The opinions of Malpighi and Ruysch have held the schools 
in perpetual controversy ; most anatomists however leaning 
to the authority of Ruysch. There follows these a crowd of 
French academicians, who, with Boerhaave, may be considered 
as mere commentators on the original authorities of Mal- 
pighi and Ruysch. Some of these argue for secretion by con- 
tinuous vessels, and contend that the arteries terminate in the 
excretory ducts ; others, that the secretions are made into fol- 
licules ; and some, as Boerhaave, insist that both are right in 
their observations, and in the proofs which they have adduced, 
that secretion is in part performed bv continuous vessels, 
partly by a more intricate glandular apparatus. 
I wish to speak with respect of Bichat, yet I cannot help 
saying that it is edifying in a way which he did not intend, to 
find him thus expressing himself. Authors have occupied 
themselves a great deal about the intimate structure of glands. 
Malpighi admits that they are small bodies of a peculiar nature, 
and Ruysch has established it that they are entirely vascular. 
Let us neglect these idle questions, where neither the eye nor 
experiment can be our guide; let us begin to study anatomy 
WThere the structure of organs come under the senses. The 
rigorous advance of science in this age does not yield to these 
frivolous hypotheses ; and so forth. Thus Bichat does not 
retrace the steps of the mechanical philosophy, nor enter into 
the science of hydraulics, nor attach himself to the newer 
school of chemical physiologists, but in truth gives origin to a 
new school, de Fart du cuisinier. He cooks it; he boils the 
liver and the kidney, &c. he dries them, boils them again ; ob- 
serves with all possible minuteness and gravity what floats in 
scum, what remains behind, what gets soft, what hardens by 
boiling ; he smells and tastes ; or he roasts the glands with the 
same ceremony, and still imagines the while he is deeply phi- 
losophical. 
Of the secretions discharged from the glands it may be suf- 
ficient to say, that many of them are destined to be useful to the 
* Ituysch’s doctrine again was thus opposed; “Ruyschius an get arte sua 
replendi extensionem vasorum ultra naturalem megnitudincm. Ruyschius arte 
sua destruitglandulas; dein negat. Euyschius negat omnes glandulas. Me- 
lius est &, tutius omnia luce demonstrave in cadavcre xecenti.” F. Ruysch 
Epist. ad Yir. (liar. Her. Boerhaave, p. 50. 
It may be further observed, that it was not in the mere fact of there being 
follicules, in which Malpighi and Ruysch dillered; for the latter conceded that 
there were hollow membranes, but contended that these were not glands. 
Hie difference of opinion is expressed in the following words of ltuysch ; 
“ Adeoque discrepantia inter magnum ilium virum et inter me est, quod ille 
jmtat humorcs delabi in glandulas dictas simplicissimas,—ibi foveri mutari 
Ego puto, quad arterise ultima; succos faciant. & factos ibi deponant.’’ 185 
further operations of the economy: that they are all liable to 
be absorbed upon any obstruction to their evacuation ; and that, 
as far as experiments on brutes go, all the animal secretions 
may be even injected into the circulating fluids without greatly 
disordering the system.* 
The blood carried into the glands has nothing peculiar in 
its appearance and sensible qualities ; the idea once entertained, 
that the blood issuing from the heart immediately commences 
a separation of its parts for the several secretions, is quite un- 
sustained ; and if it deserves a serious refutation, we have 
it in the varieties to be observed in the distribution of the 
arteries to the glands ; for a different origin of a secreting ar- 
tery would in that supposition change the secretion.f 
In some of the glands the arteries and veins have a peculiar 
appearance ; they are convoluted, and reflected so curiously, 
as to have given rise to the idea of their preparing the blood 
for the secretion ; thus in the spermatic chord the vessels have 
been called the vasa preparantia. But this convolution of ves- 
sels is for another purpose. 
Nothing peculiar has been observed in the distribution of 
nerves to the glands. They are comparatively small. They 
have been cut, and still the secretion has gone on. As however 
most of the higher and distinguishing pi'operties of life reside 
in the nervous system, so it is reasonable to suppose that not 
only the various sympathies and sensibilities which the glands 
possess are derived from the nerves,but also that the secretions 
which they separate from the general mass of blood, is owing 
to an influence of life residing in their nerves. An imperfect 
knowledge of anatomy, and especially of the connections and 
relations of the nervous system, gives rise to very useless ex- 
periments. Is it not strange that experimenters should think 
that they cut off nervous energy but cutting through the nerve ? 
This is still proceeding upon an oldfashioned opinion, that the 
brain secretes the nervous spirits, and the nerves dispense them! 
Let us be satisfied with knowing a little. The life residing 
in the gland is an agent controlling the affinities. The liver 
or the kidney secrete bile and urine, not because they have a 
certain form, but because the affinities of the particles of the 
blood are controlled by the living principle in the glands to an 
appointed end, &c. This, while it explains the peculiarity of 
glands, admits also of a vicarious secretion, that is, the pos- 
SYSTEM OF THE VTSCERA. 
* Haller, by experiments, proved that several kinds of foreign matter may 
be conveyed into the circulating blood ; and Uichat has made the experiment 
of injecting all the animal secretions into the veins of brutes. 
f Bichat has also taken the trouble of examining the blood of the carotid ar- 
tery, and of the spermatic artery, without being able to observe any dif- 
ference. 186 
INTRODUCTION. 
sibility of one gland, or surface, taking upon it the discharge 
of another. 
As the forms of the parts which throw out secretions have 
an infinite variety, it may be useful in this introductory view to 
point out these varieties, and their appropriate names.* In 
the first place, although in general language the term gland 
implies a secreting body,yet this does not follow from the defi- 
nition of that word. According to Hippocrates, it is a tumid 
round body, soft, smooth, and shining. Many such bodies, 
and which we call glands, have no excretory ducts, and do not 
secrete a fluid : while most secreting parts admit of no such 
definition. When, again, we admit the definition of authors 
who have taught their peculiar opinions regarding their struc- 
ture, we have a still less admissible description. Thus Mal- 
pighi defined a simple gland to be w Membrana cava cum 
emissarioand Ruysch says, “ Glandulae non nullae compo- 
nuntur ex sola membrana cava cum emissario sed praecipue 
ex vasis.” 
These definitions of glands being optional and uncertain, it 
is necessary to use names appropriated to the several varieties 
of form in secreting parts. Indeed the term gland is inadmis- 
sible as conveying any knowledge of the minute parts of which 
the viscera are composed. 
We must observe, however, that there is a division of glands 
still in use into conglobate and conglomerate. The first im- 
plies a gland simple in its form, the latter a gland having the 
appearance of an assemblage of several glands.f Now there 
is no gland that has not more or less the appearance which is 
described by conglomerated ; that is, consisting of several 
parts, united by cellular membrane; and the distinction is at- 
tended with no advantage. 
Acini (the stones of grapes, literally,) form the last subdivi- 
sion which we observe in the viscera, as in the liver ; they are 
round bodies, not regularly invested with membranes, and 
which can be teased out into parcels of minute vessels.:}: 
Cryptse (implies cells or cavities) are numerous in the body. 
We have an example of them in the great intestines.§ Crypt* 
* The terms acini, cotulx, crvptx, folliculi, glandulx, lacunx, loculi, utriculi 
have been almost promiscuously used; being so many names for bundles, 
bags, bottles, holes, and partitions. 
| As the salivary glands and the pancreas. Farther, the lymphatic glands are 
generally called conglobate glands, being smooth, and apparently simple in 
their structure ; but these, when injected, take exactly the appearance which 
should naturally be described by the term conglomerate, consisting of many 
little cavities. These lymphatic glands, belonging to a distinct system, require 
no farther particular definition to distinguish them. 
$ See farther of the acini of the liver for example. 
§ Ruych ad Virum Clar. II. Boerhaave, p. 53. OF THE ABDOMEN IN GENERAL. 
187 
is a soft body, consisting of vessels not completely surround- 
ed with a membrane, and resolvable by boiling or maceration.* 
Follicules are little bags appended to the extremity of the 
ducts, into which the secretion is made, and from which it is 
evacuated by the ducts. 
Lacunx are little sacs opening largely into the passages, (as 
in the urethra,) and into which generally mucus is secreted, 
which lodging there is discharged when matter moves along 
the passage. 
Finally, we have to recollect that every part of the body 
secretes ; that every surface is a secreting surface; that even 
that surface which is produced by an incision no sooner ceases 
to bleed than a secretion begins. And that an ulcer in the 
skin or flesh becomes by habit similar to those organs the 
peculiar functions of which is to secrete some matter useful 
in the system. This fact corrects the notions which we should 
otherwise be apt to receive of the action of secretion from 
contemplating the more complicated glandular organs. 
CHAP. I. 
QF THE ABDOMEN IN GENERAL, AND OF THE PERITONEUM. 
The abdomen is that division of the body which is betwixt 
the thorax and pelvis. It is bounded above by the arch of the 
diaphragm ; behind, by the spine; on the sides and forepart by 
the abdominal muscles ; and below, the abdominal viscera are 
supported by the alse ilii and the ossa pubis. The abdomen 
contains the viscera, which are for the purpose of receiving 
and assimilating the food, and the organs for the secretion of 
urine. Nature, by the classification of the parts in the great 
cavities, declares a connection of these parts in function which 
is never to be lost sight of. 
We speak of the cavity of the abdomen; but it is an inac- 
curacy of language; for there is really no cavity. The pa- 
rietes of the abdomen, viz. the abdominal muscles and perito- 
neum, closely embrace tlie contained viscera. To understand 
what is meant by the cavity of the abdomen; to understand 
* Cryptarum vascula possum docere, sed sunt tarn subtilia, ut reptatus non 
possit distingui: tantum circum affusa rubedo per repletionem videtur.” 
Kuysch ad Her, Boerhaave, p. 77. 188 
the connection of the several viscera, and the manner in which 
they lie contiguous, while they adhere at certain points only; 
we must attend to the peritoneum. But, in the first place, let 
us notice the outward divisions of the belly. 
OF THE ABDOMEN JN GENERAL. 
OF THE REGIONS OF THE BELLY. 
To give greater accuracy to the description of the seat of 
the viscera, or, perhaps rather, more strictly to connect the 
knowledge of the internal parts with the outward marks of the 
belly, it has been long customary to mark certain arbitrary 
divisions on its surface, which are called regions. 
The epigastric region is the upper part of the belly, 
under the point of the sternum, and in the angle made by the 
cartilages of the ribs. Upon the sides covered by the cartilages 
of the ribs are the hypochondriac regions, or the right and 
left hypocbondrium. These three regions make the upper 
division of the abdomen, in which are seated the stomach, 
liver, spleen, pancreas, duodenum, and part of the arch of the 
colon. The space surrounding the umbilicus, betwixt the epi- 
gastrium and a line drawn from the crest of one os ilii to the 
other, is the umbilical region, and here principally are the 
small intestines. The hypogastric region is of course the 
lowest part of the belly, consisting of the angle betwixt the 
umbilical region, the spines of the ossa ilii and the pubis. The 
two lateral spaces betwixt the false ribs and the spine of the os 
ilii, and behind the line perpencieular to the spine of the ilium, 
are the lumbar regions, or the loins: here the kidneys are 
seated and part of the colon. The hypogastric is divided into 
three, the pubic in the middle and an inguinal on each side. 
Draw a circular line round the body from the inferior margin 
of the ribs ; draw another from the superior spines of the ilium 
across the forepart of the belly ; draw a line upwards from the 
same point of the ilium; the regions are then described. 
OF THE PERITONEUM. 
The peritoneum, like all the other membranes of the body, 
consists of an expansion of dense cellular membrane; yet it is 
what is called a proper or simple membrane; being a white 
firm thin contexture of cellular substance, in which no fibre or 
striated appearance is to be observed.* By its outer surface 
it adheres to the adipose membrane, on the inside of the ab- 
* 'Fhe meaning of some anatomists, saying, that the peritoneum is a double 
membrane, will be seen below. OF THE PERITONEUM. 
189 
dominal muscles, and to the surface of the several viscera; 
its inner surface is smooth, and forms no adhesion while the 
parts are sound and healthy ; its outer surface is looser in 
its texture, and by the splitting of its lamina, it may be traced 
into the common cellular membrane. 
The cellular membrane on the outside of the peritoneum is 
in some places short, firm, and dense; as on the liver, the 
spleen, the uterus, and the intestines: but it is longer, lax, 
and fatty, where it attaches the peritoneum to the muscles 
and tendons of the abdomem. 
The peritoneum has no termination ; or it is a sac; yet so 
curiously is it involved with the viscera, that though we say 
the viscera are contained in the abdomen, yet, accurately 
speaking, they are without the peritoneum, and consequently 
lie not in the abdominal cavity. 
Let us follow it in its intricacies, and suppose that we have 
opened the sac, (that is the cavity of the belly,) we find it first 
expanded on the lower surface of the diaphragm ; and at some 
of the interstices or perforations of that muscle or its tendon it 
comes in contact with the pleura, and adheres to it by cellular 
substance. From the diaphragm the peritoneum is reflected 
off to the liver, forming the ligaments of that viscus, and, ex- 
panded over its surface, it forms its outer membrane. Fi'om 
the diaphragm it is also sent off upon the oesophagus and sto- 
mach, and prolonged to the spleen on the left side (as it is to 
the liver on the right) so as to form the ligaments of the spleen. 
The aorta, the great vena cava, the thoracic duct, and the 
kidneys, are behind the peritoneum; that membrane being 
stretched before them. But the intestines are also in the 
same respect behind this general investing membrane; for it 
is merely reflected from the spine and psoas muscles, and 
from the great vessels running clown upon the spine, so as to 
involve the intestines and form their outer coat. As it 
stretches towards the tract of the intestinal canal, it conse- 
quently involves the vessels of the intestines in its duplica- 
ture, and forms the mesentery. 
The peritoneum also lines the abdominal muscles ; it is re- 
flected from the diaphragm upon the surface of the transver- 
salis and rectus abdominis muscles. Here it is united to them 
by a loose adipose membrane, and from the abdominal mus- 
cles it is continued upon the inside of the pubes. From the 
pubes it ascends upon the bladder of urine; descends again 
behind the bladder; and there, making another reflection to 
mount over the rectum and form the meso-rectum, it leaves 
betwixt the rectum and bladder a particular sacculus. 
From this detailed description we see that the peritoneum 190 
OF THE PERITONEUM. 
has no termination; that it is continued from the surface of the 
diaphragm to that of the abdominal muscles; from that over 
the bladder and rectum; from the rectum in the whole length 
of the intestinal canal; and from the intestinal canal up upon 
the diaphragm. We see then what is meant when it is said 
that it is a shut sac ; we understand by the cavity of the perito- 
neum merely the inside of this sac; and that when distended 
with fluid, that fluid is contained betwixt the peritoneum lining 
the abdominal muscles, and that part of it which invests or 
forms the outer membrane or coat of the intestines. This 
fluid, whether collected there by disease or thrown in by ex- 
periments, has no natural outlet, nor does it transude in the 
living body.* 
BLOOD-VESSEES OF THE PERITONEUM. 
As the peritoneum is a membrane of great extent, and in- 
vesting a variety of parts, its vessels come from many sources. 
It receives arteries and veins from the mammary vessels; 
from the phrenic and epigastric vessels; from the lumbar 
arteries and veins; and from the ilio-lumbalis, circumflexa 
ilii, renal and spermatic arteries. It receives nerves from the 
intercostal, lumbar, and diaphragmatic nerves. 
It would appear that disease has given rise to the opinion 
that the peritoneum has in it many little glands. This is con- 
troverted decisively by Morgagni: there are no glandular 
bodies in the peritoneum. 
OF THE USE OF THE PERITONEUM. 
The peritoneum serves as a dense and outer coat to the 
abdominal viscera; conveys the vessels to them, as in the 
example of the mesentery; and, having its inner surface 
smooth and lubricated by a watery secretion, it allows the 
parts to lie in contact, (they being strongly compressed by 
the surrounding abdominal muscles and diaphragm,) and at 
the same time allows in the intestinal canal a capacity of 
motion without friction. 
* We not unfrequently find an accurate general description in authors, but 
some incorrectness in the subordinate detail; which throws back the ideas 
of the reader into confusion. Such is the enumeration of the holes or per- 
forations of the peritoneum, “ pour donner passage & Tossophage, & la veine- 
cave,” 8cc. See Anatom. Chirurg. par M. Palfin. We see that there are no 
such perforations, that the oesophagus never enters into the cavity of the 
peritoneum, nor does the rectum pass out from its cavity. This was indeed 
explained by Fernelius in opposition to Galen. See a description of the in- 
flections oi the peritoneum bv Bartholin.—Specimen Historic Anatomic* 
Analect. Ob. I. OF THE PERITONEUM. 
191 
There is no internal surface or cavity, as it is called, of the 
living body, which is not moistened by an exudation from the 
vessels of the surface. Thus it is with the peritoneum. An 
exhalation from the extreme arteries bedews its surface, and is 
again taken up by absorbent vessels ; so that it does not accu- 
mulate in health, nay even fluids poured into the abdominal ca- 
vity will be taken up by the absorbents.* When the abdomen 
is opened in animals alive, or recently killed, as in the sham- 
bles, a vapour is seen to exhale from the peritoneum having a 
peculiar animal odour. Yet we ought not to say that this va- 
pour is collected in the dead body: for before the opening of 
the peritoneum, or the death of the animal, it is not in a state 
of vapour, but is condensed into a watery exudation.f 
One great use of the peritoneum is to retain the viscera in 
their place, says Haller ; for when it is wounded they escape, 
and sometimes with a sudden impetus, which makes it difficult 
to reduce or retain them4 But this is not from the want of 
the embracing of the peritoneum, but from the tendons or 
muscles which support the peritoneum being cut ; for when 
there is a deficiency in the support given by the abdominal 
muscles, or their expanded tendons, the peritoneum does not 
prevent the viscera from being protruded, but easily yields to 
their forcible protrusion, and forms a sac involving this hernia. 
Nor do the processes of the peritoneum, which have re- 
ceived the name of ligaments, nor the mesentery, nor meso- 
colon, sufficiently resist the prolapsus of the viscera when they 
have escaped from the pressure of the surrounding muscles. 
Sufficient examples of this we have in hernia of the intestines, 
in which the mesentery is greatly elongated, or in the displace- 
ment of the stomach, or in the prolapsus and procedentia uteri. 
The peritoneum which forms the sac of hernia retains little 
elasticity, and does not shrink into the belly when freed from 
the outer adhesions ; but the general peritoneum will allow 
great distention, as in ascites, and quickly contract to its for- 
mer dimensions on the evacuation of the fluid; and so that 
* See Nuck Sialograph, c. ii. p. 27. 
Qua copia in Statu secundum naturam secernatur dictu difficile est: ad urn 
cias certe collecta aquula in sani hominis abdomine reperitur. (Kaavvn, 545.) In 
homine, cui sponte abdomen sub umbilico ruptum erat ad quinque & sex libras 
de die effiuebat. (Journ. de Med. 1757. M. Aug. ut denique 800 libr..effluxe- 
rent.) This, however, proves nothing of the nature or quantity of the secre- 
tion : this has probably been an inflammation and abscess of the peritoneum, 
which, we have seen, pours out such a quantity of fluid, thin and serous, as 
quickly to drop through the bed-clothes upon the floor. 
f This vapour I have seen arising from the intestines of the human body 
during the operation for hernia; and also when the omentum and intestines 
have escaped in consequence of a wound of the belly, 
t Element. Physiol, tom ii. p. 380. 192 
OF THE PERITONEUM. 
part of the membrane which invests the stomach and intes-r 
tines, the bladder of urine and gall-bladder, has considerable 
elasticity, since it suffers these parts to be distended and again 
returns to its former dimensions. 
The consideration of the insufficiency of the peritoneum to 
retain the viscera leads us to attend to a circumstance of the 
greatest importance connected with the viscera of the belly. 
The abdomen is every where (except towards the spine) sur- 
rounded by muscles. Above we see the diaphragm ; before, 
and to the sides, the abdominal muscles ; and even below, the 
parts in the pelvis are surrounded and compressed by the leva- 
tor ani, in such a manner that the whole of the viscera suffer a 
continual pressure. This pressure upon the viscera appears 
to be uniform and constant, notwithstanding the alternate ac- 
tion of the abdominal muscles and diaphragm as muscles of 
respiration : but it must be occasionally very violent during 
exertions ; in pulling, for example, or in straining, as a sailor 
must do in working of the great guns, or when pulling at the 
oar, or when balancing himself upon his belly over the yard- 
arm. And indeed by such violent and general compression 
of the viscera of the belly, ruptures are sometimes produced, 
of the worst kind, and followed by an immediate train of 
urgent symptoms. 
The viscera having in general delicate outer coats, and no 
ligaments capable of supporting them, and being very vascular, 
require the support of this pressure of the surrounding muscles; 
and the great venous trunks which take their course through 
the abdomen are in a particular manner indebted to the pres- 
sure of the abdominal parietes. We must recollect also the 
bad consequences which result from the sudden relaxation of 
the abdomen ; as in women after delivery, or in consequence 
of withdrawing the waters of ascites without due compression 
of the belly; languor, faintness, and even death, are some- 
times produced, apparently by the balance of the vascular 
system being destroyed. 
Some good authors in former times have described the peri- 
toneum as a double membrane.* This was no farther a mis- 
take than as they considered the cellular membrane, which 
lies without the peritoneum, as a part of it. It is necessary to 
recollect this in order to understand the meaning of their call- 
ing the sheath of the cellular membrane, which accompanies 
the vessels passing out from the abdomen, productions of the 
peritoneum. The vaginal productions of the peritoneum are 
the sheaths of the common cellular substance which accom- 
* See Anat. Cliirug. par M. Palfin. tom. ii. p. 35. and note a. OP THE PERITONEUM. 
193 
pany the aorta and (esophagus into the posterior mediastinum; 
or which give a bed to the spermatic vessels, or passing under 
Poupart’s ligament accompany the vessels of the thigh. They 
are improperly termed productions of the peritoneum. 
The proper productions or prolongations of the peritoneum 
are of a very different kind ; they are the ligaments and plicae, 
the mesentery, mesocolon, omenta. 
OF THE LIGAMENTS AND FOLDS FORMED BY THE PERITONEUM. 
There are certain ligaments and plicae formed by the peri- 
toneum, which to enumerate will carry us again overall the ex- 
tent of its surface. When this membrane is reflected off to the 
oesophagus from the diaphragm, it forms 1. the ligamcntum 
dextrum ventriculi; and 2. the vinculum oesophagi. In the 
same manner is formed, 3. the ligamentum inter cesophagum el 
lienem, which we may trace into the omentum majus, presently 
to be described. From the spleen we may trace the mem- 
brane into, 4. the plica renalis and capsular is: 5. another plica 
or duplicature, may be traced from the kidney to the colon, 
and on the right side, 6. the plica duodeno-renalis, viz. from the 
kidney to the duodenum. When we turn up the liver, we are 
led to observe the five ligaments to that viscus, to be described 
in their proper place, and from the liver stretching to the kid- 
ney we find the 7. ligamentum hepatico-renale still tracing the 
convolutions of the intestines, and following the mesentery or 
ligament of the small intestines, into the mesocolon, or liga- 
ment of the great intestines, and the mesorectum or process 
of the peritoneum to the rectum ; we there see the 8. plica semi- 
lunaris, which is before the rectum, and behind the bladder 
of urine. 
The young anatomist ought to trace all these processes of 
the pt f-Honeum, both to comprehend the great extent of sur- 
face exhibited by this membrane, and the relations of the vis- 
cera to each other. 
OF THE OMENTA. 
The omenta are considered as secondary processes of the 
peritoneum, because they are not formed by the peritoneum 
reflected off from the spine upon the intestines, as the mesen- 
tery is,—it being a primary process ; but they are reflected 
from the surface of the stomach and intestines. Anatomists 
distinguish the omentum majus, or colico-gastricum; the omen- 194 
OF THE PERITONEUM. 
turn minus, or hepatico-gastricum ; omentum coiicum, dextrum 
and sinistrum ; and, lastly, the appendices epiplo'ica. 
The omentum, or epiploon, meaning thereby the great 
omentum, is a floating membrane of extreme delicacy, expand- 
ed over the surface of the small intestines, and attached to the 
great arch of the stomach and intestinum colon. Although 
this membrane be of extreme delicacy and transparency in 
the young subject,* yet it is much loaded with fat, and appears 
transparent in the interstices only; and in advanced age it 
loses much of its delicacy, and acquires a degree of diseased 
consolidation or firmness, and is often irregularly collected 
into masses, or adheres preternaturally to some of the viscera. 
The omentum majus hangs suspended from the cellular 
connection betwixt the arch of the stomach and the great 
transverse arch of the colon; or rather it forms that connec- 
tion betwixt the stomach and colon. It consists of two mem- 
branes, or is as a sac collapsed and hanging from the stomach 
and colon,f one of the sides being the peritoneum reflected off 
from the oesophagus and along all the great arch of the sto- 
mach, and the other that which comes from the arch of the 
colon. And further, each of these lamina may be supposed 
to consist of two lamina ; for example, where the omentum is 
formed by the meeting of the peritoneum from the lower and 
upper surfaces of the stomach; these two uniting, form the 
upper lamina: and where the lower layer of the omentum 
comes off from the colon, it is also formed by the peritoneum 
reflected in the same manner from both sides of that intestine ; 
so with some truth the omentum is supposed to consist of four 
lamina of membranes of extreme tenuity : but these four lay- 
ers cannot be demonstrated. The great omentum extends 
from the bosom of the spleen transversely until it terminates 
on the right side of the arch of the colon, where the omentum 
coiicum begins. 
The great omentum varies considerably in extent. In a 
child it is short; in the adult further extended over the visce- 
ra : sometimes it reaches only to the umbilicus ; sometimes 
it is allowed to extend its margin into the pelvis, so that in old 
people it is very apt to form a part of the contents of hernia ; 
often it is wrasted and shrunk ; sometimes collected into masses 
leaving the surface of the intestines. 
My reader must now find his way into the marsupium, or 
* Prseterea tenerrimas esse ut nulla membranarum humanarum, retina oculi 
excepta, seque sit tenera. Haller, vol. vi. lib. 20. § 1. par. 12. 
its delicacy is remarkable in the young1 subject, the retiform vessels 
■Vvid I her. II. Q. V. Spegil. LVI1I. &c ) have the fat accumulated in 
their tract as it were thrown up by them to a side ; but often the fat increasing 
obscures the vessels 
f Marsupium the common term.—See Winslow. IV. § 352. Q¥ THE PERITONEUM. 
195 
purse of the omentum, viz. the porta omcnti, the celebrated 
foramen of Winslow. It will be found to be a slit betwixt 
the ligamentum hepatico-colicum and hepatico-duodenalis, 
being under the biliary vessels and vena portae. Upon blow- 
ing into this opening, in a young subject, three omenta are 
distended viz. the omentum hepatico-gastricum, the colico-gas- 
tricum, and the colicum. 
This opening serves as a communication betwixt the cavities 
of the omentum and the general peritoneal cavity; but I am 
inclined to think it is very frequently destroyed by adhesions.* 
As this opening points towards the right side, Dr. Monro 
thinks it a sufficient reason for introducing the trocar on the 
right side in the operation of tapping for ascites: (contrary to 
the usual caution of avoiding the liver, which is so often dis- 
eased in this case,) by operating on the left side he thinks 
the water will not be allowed to flow from the sac of the 
omentum. It appears to me that it will flow equally well 
from whatever point of the belly the water is drawn. 
OF THE OMENTUM MINUS, OR HEPATICO-GASTRICUM. 
This is a membrane of the nature of that last mentioned, 
but in general less loaded with fat. It is extended from the 
liver to the lesser arch of the stomach. It passes off from the 
lower surface of the liver at the transverse fossa; from the 
fossa ductus venosi; invests the lobulus spigellii; involves 
the branches of the caeliac artery; and is extended to the 
lesser curvature of the stomach and the upper part of the 
duodenum, f 
OMENTUM COLICUM. 
This is a continuation of the great omentum upon the right 
side of the great arch of the colon, where it rises from the 
caput coli; but it seldom extends its origin from the colon the 
length of the caput coli. It is inflated with the great omentum. 
APPENDICES EPIPLOlCiE, OR OMENTULA INTEST1NI GRASSI, 
These are little fatty and membranous processes which 
hang pendulous from the surface of the colon : they are of 
* Winslow, Duverney, and Haller. 
f “ Macilentius es, et vasa habet minora.” Winslow. Haller. Indeed it 
seems rather to answer the general purpose of a cellular membrane convey 
mg vessels, than the purposes of the omentum majus. 196 
OF THE ABDOMEN. 
the same texture and use with the greater omentum and right 
colic omentum. 
We have mentioned that the omenta are double reflections 
from the peritoneum, and consequently they may be inflated 
so as to demonstrate them to be perfect sacs. To do this it 
is not required to puncture any part of them, for by the natu- 
ral opening just described, the whole may be inflated in a 
young subject, and in a healthy state of the viscera. 
There is a considerable variety in the form of the omentum 
of animals,* but still they seem to show the same provision of 
involving the intestines, filling up the inequalities which arise 
from the rounded forms of the viscera, and still further lubri- 
cating and giving mobility to the intestines.f The surface of 
the omentum, however, seems merely to furnish a fluid exuda- 
tion like the general surface of the peritoneum; and the idea 
which has been entertained of the oil or fat exuding is not 
true.:}: 
The use assigned to the omentum of being subservient to 
the function of the liver is deservedly neglected.^ 
CHAP. II. 
OF THE VISCERA OF THE ABDOMEN. 
Having understood the nature of the general investing- 
membrane of the abdomen, and what is meant by its cavity 
and its processes, we take a general survey of the economy of 
the viscera, before entering upon the minute structure of the 
parts individually. 
The contents of the abdomen are thus enumerated in ele- 
mentary Avorks on anatomy. 
1. The membranous viscera, viz. the stomach, the small 
and great intestines, the gall-bladder, mesentery, the meso- 
colon, and ligamentous processes, and the omenta. 
* Haller Element. Physiol, tom. vi. lib. xx. § 2 and 3. 
f We must not suppose because a madman stabs himself in the belly, and 
there is afterwards found coalition of the intestines to the wounds, the omen- 
tum has not done its office, (see Boerhavii Prelectiones, vol. i. § 45.) no more 
can we give credit to the tale told by (Galen (I)e Usu Partium, 1. iv. c. 9.) of 
the gladiator who lost part of the omentum, and ever after had a coldness in 
his guts! at least we cut out a great part of the omentum from a man without 
any such sensation being the consequence now-a-days. 
t “ Et dum halitu pingui & ipsa obungit & peritoneum.” Hal. loc. cit. 
Boerhaave, &c. Morgagni Adversar. III. Animad. VI. 
§ Viz. by supplying a gross oily matter to the vense portae. OF THE ABDOMEN. 
197 
2. The solid viscera, viz. The liver, spleen, pancreas, 
the kidneys, and renal capsules, the mesenteric glands ; but a 
natural order in the arrangement of these viscera is to be 
preferred. 
The organs destined to receive the food, and to perform the 
first of those changes upon it, which fit it (after a due succes- 
sion of actions) for becoming a component part of the living 
body, are the stomach and intestines primarily ; the glandular 
viscera, the liver, pancreas, and the spleen, are subservient or 
secondary organs. I have been accustomed in my lectures to 
divide these parts into those which have action and motion, 
and those which are quiescent or possessed of no power of 
contraction. Thus the stomach, intestines, gall-bladder, and 
bladder of urine (though this belongs to the pelvis) have mus- 
cular coats, and the power of contracting their cavities; while 
the liver, spleen, pancreas, and kidneys, have no muscularity 
but in their vessels and excretory ducts. 
This division of the viscera may lead to important distinc- 
tions in pathology. During inflammation, it is observed, that 
though the parts possessing a power of contraction may some- 
times lie inactive without pain, yet in those parts when roused 
to action there is excruciating pain. On the other hand, it 
often happens that the glandular and solid viscera are the seat 
of long continued disease, which is attended only with a dull 
or low degree of pain; while the anatomist is often struck upon 
examining the body after death with the wide ravages of the 
disease. 
We divide the intestinal canal into three parts; the stomach, 
the small intestines, the great intestines. The small intestines 
are subdivided into the duodenum, jejunum, andileon. The 
great intestines are subdivided into the csecum, colon, ancl 
rectum. The stomach is the seat of the digestive process: 
in the duodenum the food receives the addition of the secre- 
tions from the liver and pancreas, and is still further changed; 
in the long tract of the jejunum and ileon the nutritious part is 
absorbed; and in the great intestines the foul sediment be- 
coming faeces is carried slowly forward, suffers a further ab- 
sorption of fluid, lodges in the lower part of the colon, and 
then in the rectum or last division of the canal. 
From this view it is apparent that as each division of the in- 
testinal canal is marked by some peculiarity in its use or func- 
tion, we must carefully examine their minute structure as in- 
dividual parts, at the same time that we do not allow ourselves 
to forget the universal connection, the integrity of the circle 198 
OF THE CESOPHAGUS. 
of actions, and the economy as a whole. With this intention, 
following the course of the food, we treat first of the oeso- 
phagus. 
SECTION I. 
OF THE CESOPIIAGUS. 
The oesophagus or gullet is a cylindrical muscular tube, 
which conveys the food to the stomach. It is continued 
from the pharynx down behind the larynx and trachea and 
close before the spine, and continuing its course in the back 
part of the thorax, it perforates the diaphragm, and expands 
into the upper orifice of the stomach. 
Although with many authors I call it a cylindrical tube, and 
it may take this form when dissected from the body and in- 
flated, yet during life it lies collapsed with its inner membrane 
in close contact, and it transmits the morsel only by the con- 
tinued succession of the contraction of its fleshy coat. 
The upper part of this tube is called the pharynx. It may 
be described as being expanded like a funnel ; it is attached 
to the occipital bone, pterygoid processes of the sphenoid 
bone, and jaw-bones ; and further down it is kept expanded 
upon the horns or processes of the os hyoides. This bag is 
very fleshy, being surrounded with muscular fibres, which take 
their origin from the neighbouring fixed points ; as the styloid 
process, the horns of the os hyoides, the thyroid cartilage ; by 
which it is enabled to grasp and contract upon the morsel 
when it has been thrust by the tongue behind the isthmus 
faucium. This strong tissue of muscular fibres which surrounds 
the pharynx, is continued down upon the oesophagus in the 
form of a sheath, which has been called tunica vaginalis. 
I believe we can with propriety enumerate no more than 
two proper coats of the oesophagus ; its muscular and internal 
coat: for that which is sometimes considered as the outer 
coat, is only the adventitious cellular membrane, and the 
nervous coat is merely cellular tissue connecting the muscular 
and inner coat. 
The muscular coat of the oesophagus greatly surpasses in 
strength and in the coarseness of its fibres any part of the 
whole tract of the intestinal canal. There may be very dis- 
tinctly observed in it two layers of fibres; an external one con- 
sisting of strong longitudinal fibres, and an internal one of cir- 
cular fibres. These lamina of fibres are more easily separated OE THE OESOPHAGUS. 
199 
from each other than those in any other part of the body.* 
But an idea is entertained that the one set of fibres, the circu- 
lar and internal ones, are for contracting the tube, and the 
outer ones for elongating and relaxing it. I believe on the 
other hand, that they contract together, conducing to one end, 
deglutition.f 
What is called the tunica nervea is the cellular connec- 
tion betwixt the muscular and inner coat, and is very lax, 
insomuch that the muscular coat and the inner coat are like 
two distinct tubes, the one contained within the other, and 
but slightly attached. This appearance is presented particu- 
larly when the oesophagus is cut across. 
The inner coat of the oesophagus is soft and glandular; 
villi are described as being distinguishable on its surface, and 
it is invested with a very delicate cuticle which dulls the acute 
sensibility, and prevents pain in swallowing. It in every re- 
spect resembles the lining membrane of the mouth. The power, 
however, which the oesophagus seems to possess of resisting 
heat depends not on the insensibility bestowed by the cuticle, 
but is owing to the rapid descent of the hot solids or liquids 
swallowed; for when they happen to be detained in the gullet 
they produce a very intolerable pain. This inner coat has an 
exhaling surface, like the rest of the body, with particular 
glands to secrete and pour out that mucus which lubricates 
the passage for the food. These glands suffer ulceration and 
scirrhous hardening, and are a terrible cause of obstruction 
to swallowing. The inner coat is capable of a great degree 
of distention, but it is not very elastic, or at least contraction 
of the muscular coat throws it into longitudinal folds, or plicae. 
In the neck the oesophagus lies betwixt the cervical vertebrae 
and the trachea, but is at the same time in a small degree 
towards the left side. At the bottom of the neck it perforates 
the membranous fascia, and enters the thorax. Here the sur- 
geon should take good heed of the relation of the tube to the 
fascia, for I have seen a stricture imagined to be present from 
an instrument resting on this membranous connection. When 
the oesophagus has entered the thorax it descends retiring a 
little backwards at the same time, and passing behind the 
bifurcation of the trachea and the arch of the aorta, when it 
* It appears that the oesophagus can be ruptured in two ways: across, by 
the tearing of the longitudinal fibres; and longitudinally, by the separation 
of the longitudinal fibres. This, though a rare accident, takes place in vio- 
lent vomiting or straining to vomit; and, in the first instance, the tearing 
across of the oesophagus seems to be the effect of the action of the diaphragm 
on the oesophagus. By this accident the fluids of the stomach are poured 
into the cavity of the thorax. 
f See far her of the muscular coat of the intestines. “ It was at one time 
supposed that the muscular fibres of the oesophagus had a spiral direction.” 
See Verheyn, and Morgan. Adversar. iii. 200 
OF TIIE STOMACH. 
descends farther upon the dorsal vertebras, it lies rather to the 
left side; escaped from the aorta, it lies on the right side of 
it, and as it passes further down it gets more and more before 
the aorta. This is sufficiently apparent when we attend to 
the relation of the perforations in the diaphragm for transmit- 
ting the aorta and the oesophagus. 
Behind the oesophagus, in the thorax, there are one or two 
lymphatic glands, which were understood by to be- 
long to the (esophagus. What deceived him is an appearance 
to be observed in these glands. The lymphatics, or the small 
branches of veins, are generally filled with a black matter, 
which, extending to the coats of the oesophagus, resemble very 
much the ducts of the glands going to open into the oesophagus. 
These glands in the posterior mediastinum are sometimes 
diseased and enlarged so as to compress the oesophagus, and 
to cause so permanent an obstruction of deglutition as to 
occasion death. 
The inner coat of the oesophagus shows so very different a 
texture from that of the stomach, and this difference is marked 
by so very abrupt a line, as sufficiently to indicate that the 
fluids poured out from the oesophagus are very distinct from 
those of the stomach, and have probablv no digestive property. 
SECTION II. 
OF TIIE STOMACH. 
The stomach is that capacious membranous bag into 
which the (esophagus delivers the food, and in it is perform- 
ed the process of digestion. The food of animals is of various 
kinds, and the form and structure of the stomach varies accord- 
ing to the nature of the food. Animal food affords that rich 
aliment in a state nearly prepared for supplying the deficien- 
cies of the living system. In such animals as live on flesh the 
stomach is simple in its form, and possesses little musculai 
property. On the contrary, vegetable food has a smaller pro- 
portion of nutritious matter in it, and requiring for its separa- 
tion a more complicated and tedious process of maceration, 
trituration, and digestion. Therefore in brutes living on vege- 
table matters we observe a more intricate system of vessels or 
reservoirs, all separating and preparing the food for the ope- 
ration of the digesting stomach or true stomach. The human 
stomach is simple compared with the stomach of the herhivtv OF THE STOMACH. 
201 
rous animals, but more curiously guarded to retain and fully 
to operate upon the food than the carnivorous stomach. 
Since I am entering on this subject I may add, that the 
length and intricacies of the intestines hold always a relation 
to the form of the stomach. If the food of an animal be of 
difficult digestion, and offer little nutriment, as it requires a 
complicated stomach, so will it require to be carried through 
the intestines long and intricate, that opportunity may be given 
for the whole nutritious matter to be absorbed and turned to 
use. But if, on the contrary, the food be rich in nutritious 
matter, the intestines will be shorter, more direct, and have 
less of that apparatus intended to delay the course of the 
contents. 
Seat, Form, Displacement of the Stomach. 
The stomach lies under the margin of the ribs of the left 
side, and chiefly in the left hypochondrium. Its greater 
extremity is on the left side, in contact with the diaphragm ; 
but towards the right, the shelving edge of the left lobe 
of the liver is betwixt it and the diaphragm. On the lower 
part it is, by the mesocolon and arch of the colon, divided 
from the small intestines ; and to the greater extremity the 
spleen is attached by vessels, and by the loose intertexture 
of the omentum. The stomach may be said to be a conical 
sac ; the extremities of which being made to approach each 
other, gives it the curve of a hunter’s horn, and gives occasion 
to the anatomist, in strict description, to remark these parts ; 
the superior or cardiac orifice, into which the (esophagus 
expands ; the lower or pyloric orifice, which leads into the 
duodenum; the lesser and greater curvatures of the 
stomach ; and the great bag towards the left where the spleen 
is attached. 
The lesser curvature of the stomach extends from betwixt 
the two orifices ; includes in its embrace, the spine, the aorta, 
and the small central lobe of the liver, while there is attached 
to it the lesser omentum. The greater curvature of the stomach 
is the outline of its distended belly, which rises above the arch 
ol the colon, and is marked by the course of the gastro-epi- 
ploic vessels. 
In the foetus, the stomach lies more perpendicular than 
transverse. In the adult, when the stomach is distended, the 
lower orifice is nearly on a level v/ith the upper one ; but when 
the stomach is allowed to subside, it falls considerably lower; 
so that whilst the stomach lies across the abdomen it is also 
tending obliquely downwards. The ensiform cartilage will be 202 
OF THE STOMACH. 
found to present to the middle of the stomach ; and the lower 
orifice, when in its natural situation, is opposite to the fossa 
umbilicalis of the liver ; the upper orifice is kept constantly in 
one place from the stricter connection of the oesophagus with 
the diaphragm. 
Both orifices of the stomach present backward, especially 
the upper one, while the lower one is pointed backward and 
downward. By the distention of the stomach the great arch 
is extended, the orifices are directed more backward and to- 
wards each other, and especially the greater extremity draws 
upon the oesophagus. By these means I conceive that there 
is sometimes produced a difficulty of the stomach discharging 
its contents when greatly distended, the orifices being in a 
great measure turned from the oesophagus and duodenum. 
The stomach being liable to frequent varieties in its degree 
of distention, the natural relation of parts must frequently be 
altered. It ought to be particularly recollected, that in the 
living body the stomach is supported and bound up by the in- 
testines so that the great curve presents: and the broad an- 
terior surface which the stomach presents in the dead body is 
turned directly upward, and the inferior downward.* By the 
collapsing of the stomach and the consequent falling down of 
the liver, some have explained .the sensation of hunger, con- 
ceiving that the uneasy sensation proceeds fi'om the liver being 
allowed to hang Upon the broad ligament.f From the great 
simplicity of mechanical explanation physicians have eagerly 
indulged in them, but it Avill in general be found, that when 
they are applied to the explanation of the phenomena of a 
living body they lead to erroneous ideas. 
In describing the human stomach as a conical bag curved, I 
speak of what Ave shall commonly observe in the dead body. 
But sometimes I have found the stomach divided into two sacs, 
and more frequently have I seen a contraction in the centre of 
the stomach from muscular action. The two last subjects for 
public demonstration, I found divided into two sacs. Riolan 
demonstrated this in 1642. Schneider and Dionis have given 
us such instances, and Morgagni has expressed an opinion that 
these were not divisions, but only contractions of the stomach. 
In fact, we meet with a permanent, as well as an occasional, 
form of the human stomach, in which there is a division into 
two sacs. 
* Tims the gastro-epiploic artery presents directly forward. It has been 
wounded, and bled both into the stomach and outwardly. I should conceive 
it possible in such a case to tie the artery. 
-j- Winslow. OF THE STOMACH. 
203 
But it is to Sir Everard Home we owe the knowledge of 
the fact, that the stomach is divided into two parts by muscular 
contraction. He is of opinion that the cardiac and pyloric por- 
tions, thus divided, perform distinct offices. 
op THE COATS OF THE STOMACH. 
The coats or membranes forming the stomach are the 
outer, the muscular, the nervous or vascular, the villous, and 
the three cellular coats. For some of these subdivisions, 
however, I see no use, nor are they authorized by the natural 
appearance of the coats of the stomach. When there is a 
distinction in texture, structure, of function, and where these 
lamina can be separated, we shall consider them as coats; 
but a mere intermediate tissue of vessels, or the connecting 
cellular membrane, are improperly considered as distinct 
tunics. 
First coat.—From what has been already said of the pe- 
ritoneum, it will readily be allowed that the outer coat of the 
stomach is formed by the peritoneum ; a coat common to all 
intestines. Were this not sufficiently evident in itself, it might 
be ascertained by dissecting the peritoneum from the cardiac 
orifice of the stomach, where it will be found reflected from 
the diaphragm. This coat is firm, simple in its texture, hav- 
ing no apparent fibrous texture, and smooth on its outer sur- 
face, with many minute vessels. Under the peritoneal coat is 
the first cellular coat, being in fact a short cellular tissue be- 
twixt the peritoneal coat and the muscular coat. 
Muscular coat.—The muscular coat of the stomach con- 
sists chiefly of several lamina of fibres; less distinct however 
than those of the oesophagus, or, in other words, more loosely 
and irregularly connected.* 
These muscular fibres of the stomach do not run in an unin- 
terrupted course, but split, rejoin, and form a kind of retiform 
texture, through which the coats beneath are at intervals dis- 
cernible. This structure would appear to bestow a greater 
power of contraction on the stomach. The strong longitudi- 
nal fibres which are seen upon the oesophagus form the outer 
stratum of the muscular coat of the stomach, and they extend 
from the oesophagus and cardiac orifice in a stellated form 
along the upper curvature, and downward upon the great end 
or sacculus ventriculi. Then we have to observe a set of dr- 
* The most general opinion is, that there are three layers of fibres in the 
stomach. Some describe an external longitudinal series: a middle transverse 
stratum : and again the internal fibres running longitudinally. See Galeati 
Acad, de 1‘oiogne. 204 
OF THE STOMACH. 
cular fibres, which forming rings upon the great end, extend 
over all the stomach, like the circular fibres of the arteries. 
These fibres do not each encircle the stomach entirely, but 
while their general direction is circular, they are so interwoven 
that no one fasciculus can be followed to a great extent. 
These are called the transverse fibres or stratum; while 
the deepest stratum consists of the continued circular fibres of 
the oesophagus. These last fibres are strong upon the cardiac 
orifice, and maybe presumed to form a kind of sphincter; but 
they diminish as they are remote from the superior orifice. 
The lower or pyloric orifice of the stomach, however, is more 
carefully guarded by muscular fibres ; having in the dupli- 
cating of the inner coats a distinct circular ring of muscular 
fibres. 
The cellular tissue, being intermingled with the muscular 
fibres, connects and strengthens them, and gives the appear- 
ance of little white lines interwoven with the muscular fibres, 
and which some have described as small tendons.* There is 
also to be observed a broad ligamentous band on the two flat 
surfaces of the stomach towards the pylorus. They are like 
the bands of the colon, but not nearly so strong or evident. 
They are formed by the denser nature of the cellular tissue, 
and more intimate union betwixt the first and second coats. 
OF THE ACTION OF THE MUSCULAR COAT. 
Upon considering the weakness of the muscular fibres of 
the stomach, and the membranous nature of the whole coats, 
it appears that the general action of the stomach is slow, re- 
gular, and by no means a forcible contraction ; not an appa- 
ratus for triturating the food, and merely giving motion to its 
contents. But regarding the extreme sensibility of the sto- 
mach, and the gradual and regular succession of action, much 
will be found that is worthy of attention.f It should seem 
that the morsel is sent down into the oesophagus by a succes- 
sion of actions, preceded by a perfect relaxation; and that 
when the food arrives at the superior orifice of the stomach, 
by the same relaxation preceding the contraction, the mus- 
cular fibres of the upper part of the stomach yield and receive 
the food compressed by the oesophagus. Attending to the 
form of the stomach, we see a provision for the reception of 
the food into the great sacculated fundus on the left extremity. 
And here we shall find that there is a greater profusion of 
vessels for the secretion of the juices of the stomach, and a 
* See Winslow, sect. viii. p. 57. 
f See Haller’s Experiments. Opera minora, Ventriculus Motus peristalticus. OF THE STOMACH. 
205 
set of the muscular fibres, probably relaxing and yielding to re- 
ceive the food, and excited to action only when the process of 
digestion has been in part or entirely accomplished. Often, 
on dissection, I see the sac or left extremity of the stomach 
distended, when towards the right extremity it is like the in- 
testine in form. We have proof, that when the food has re- 
mained the usual time in the great sac of the stomach, and 
comes in succession to be presented at the lower orifice, if the 
stomach be healthy, and the change upon the food perfect, 
the lower orifice is relaxed, and yields to the contraction of 
the muscular fibres of the stomach, and the contents of the 
stomach are passed into the duodenum: but if the food has 
been of an indigestible nature, it is rejected. The pyloric 
fibres refuse the necessary relaxation, and by the unnatural ex- 
citement an antiperistaltic motion is produced, and the matter 
is again thrown into the great end of the stomach, or rejected 
by vomiting.* There is in the natural action of the stomach 
a stimulus, followed by a regular succession of motion in its 
fibres, conveying the contents from the upper to the lower ori- 
fice of the stomach. Of this excitement and action we are not 
conscious ; but when the action is disordered by an unusual 
excitement, the lower orifice is not unlocked, the action be- 
comes violent (the reverse of what naturally takes place,) and 
pain or uneasy feelings are produced. Upon this principle may 
be explained the nausea and vomiting which take place at cer- 
tain times after eating, when balls or concretions are lodged in 
the stomach. While the food lies in the greater extremity or 
in the body of the stomach, and the ball or concretion with it, 
there is no great excitement; but when it has suffered the ne- 
cessary change, and is approaching to the pyloric orifice, this 
part, being as it were a guard upon the intestines, is suddenly 
excited, vomiting is produced, and the ball is thrown into its 
old place in the sacculus or great end. 
An attempt has been made to distinguish the affections of 
the stomach according as they proceed from the vitiated secre- 
tion, or the disordered muscular action. For example, it has 
been said, if there is pain when the stomach is empty, then is it 
owing to the secretions of the stomach hurting the coat; if there 
be pain when the stomach is full, or at regular periods after 
taking food, then is it proceeding from disordered muscular 
action. This is settling the whole difficulty on too easy terms. 
The function of the muscular fibre and of the secreting vessels 
are not thus distinct. The motion of the stomach itself and 
the secretions into it are actions conducing to a general result, 
* It would seem that the upper orifice of the stomach has a power of con- 
traction on unusual stimulus applied. Haller loc, cit. Exp. ccciii. 206 
OF THE STOMACH. 
and nature has secured the end by combining the means ; and 
vitiated fluids poured into the stomach even by its own vessels, 
are attended with irregular spasmodic pains. 
This great sensibility, producing effects almost like intelli- 
gence, is apparent in the more common disorders of the sto- 
mach. We shall find the meteorismus ventriculi (the great 
distention of the stomach by flatus) existing for weeks, and yet 
the food passing in regular course through its orifices. We 
shall find very frequently food of difficult digestion lying in the 
stomach and oppressing its functions for days, while food 
more recently received may have undergone the actual changes, 
and have passed through the pylorus into the duodenum. 
Owing to the same slow and successive action of the sto- 
mach, it often happens that ulceration and scirrhous pylorus, or 
other obstruction of the lower orifice of the stomach, is attend- 
ed with pain, nausea and vomiting, only at stated intervals 
after taking food ; i. e. at the time in which the food should be 
sent into the intestines in the natural course of action. 
The muscular fibres of the stomach are excited by stimuli, 
applied, not to their substance, but to the contiguous coats ; 
and betwixt the delicate surface of the inner coat and the mus- 
cular fibres there is the strictest sympathy and connection. The 
same connection holds in a less intimate degree betwixt the 
outer coat and the muscular fibres ; for when a part on the sur- 
face of the stomach of a living animal is touched with acid or 
stimulating fluids, the part contracts.* The stomach is consi- 
dered as less irritable than the intestines, because it is alleged 
that a stronger dose of a medicine is required to prove emetic 
than to act as a purgative : but we ought to consider that the 
action thus excited in the intestines is merely an acceleration 
of their secretions ; but vomiting is the interruption of the usual 
action, requiring such a violent excitement as to invert the na- 
tural action. 
But there is something more than this ; as the function of the 
stomach differs from that of the intestines, so may the quick- 
ness of their action. Thus in the stomach a gradual change 
is to be produced upon the food, requiring time and a slow 
degree of motion ; but in the intestines there is a greater agi- 
tation of their contents, and a quicker action of their coats, to 
bring the fluids into more general contact with the absorb- 
ing surface, and to give greater activity probably to the absorp- 
tion by the lacteals. I am inclined to think that the stomach 
* “ In ea sede qua tang'itur, contrahitur, sulcusque profundus nascitur, et 
rugae; cibusque aliquando propellitur ut a sede : contractu fugiat. Minus ta- 
men quam intestina ventriculus irritabilis est; bine emetica fortiora necessc 
est purgantibus.”—Haller. OF THE STOMACH. 
207 
is the most irritable part of the body, and susceptible of the 
most minute distinctions in the nature of the stimuli applied 
to it. The phenomena of the living animal, and experiments 
in those recently killed, sufficiently prove the contractile 
powers of the two orifices. Experiments have been made 
which show the powers both of the cardiac and of the pyloric 
orifices, in retaining the contents of the stomach after the oeso- 
phagus and duodenum have been cut across. The stomach 
of a rabbit has been squeezed in the hand after cutting the 
duodenum, without any of its contents having escaped ;* and 
in similar experiments, the finger being introduced into the 
lower orifice of the stomach of an animal yet warm, the fibres 
of the pylorus were found to contract strongly upon it. Upon 
forcibly compressing the stomach, the food will be made to 
pass into the oesophagus much more readily than into the 
duodenum ; which is another proof how necessary the natural 
series of actions is to the relaxation of the pylorus. 
Rumination.—As it is found that some individuals rumi- 
nate, and that even such a habit may be acquired, it must be 
right to say a few words on this subject.—In the ruminating 
quadrupeds the food passes into the paunch. The paunch 
consists of a larger .and smaller cavity, and from the lesser ca- 
vity the food is regurgitated into the mouth, to suffer mastica- 
tion. When a second time swallowed, it is let into the third 
cavity, which is the true digesting stomach, and from the third 
it passes into the fourth cavity, and from that into the intes- 
tines. The human stomach cannot perform an operation so 
complicated as this. But the different directions which the 
food takes in the stomach of the ruminant animals in their in- 
structive motions, closing or adjusting the slits of the oesopha- 
gus, or the openings of the several bags, proves to us that many 
silent and curious operations may be going forward even in 
the human stomach. Something we might suppose would be 
learned from th? feelings of such men as chew the cud ; but it 
happens that the best recorded instance occurred in one, a 
mere brute in intellect.! Here the morsel was brought up 
from the stomach by aVvery slight effort; it was chewed and 
swallowed : after a pause another morsel was brought up, and 
underwent the same process, This being swallowed, he ate 
his food voraciously and without chewing. There is no his- 
tory of dissection on record except on the authority of Fabri- 
* See a paper in the 3d vol. of Sandifort, Tlies. 
An excellent plate of the Pylorus is given with this Dissertation—Morgagni 
Adversar.III. IV. de Ventriculi Struct. 
+ By Sir Everard Home. 208 
cius ab Aquapendente, who found the oesophagus remarkably 
muscular. 
It is probable in the rumination of man that the great left 
extremity of the stomach serves the purpose of a temporary 
receptacle, and that in the first process it is not admitted gene- 
rally to the cavity of the stomach, or towards the pyloric ex- 
tremity. 
Of vomiting.—When there is an unusual or unnatural irri- 
tation on the stomach, or when it is violently stimulated or 
opposed in its natural course of action, the motion becomes 
inverted ; and drawing by sympathy other muscles to its aid, 
the contents of the stomach are evacuated by vomiting. Thus 
where the food takes changes inconsistent with healthy diges- 
tion ; or when solid matters lodge in the stomach ; or when se- 
cretions of the duodenum pass into the stomach, or unusual 
actions are propagated backwards upon the stomach from the 
upper portion of the canal; or when emetics are taken which 
are unusual stimuli; or when there is inflammation in the sto- 
mach, which, from giving greater sensibility, produces the 
same effect with more violent stimuli ; or when the coats are 
corroded or ulcerated ;—vomiting is produced. That vomit- 
ing may be produced by the inverted motion of the stomach 
and oesophagus alone, is apparent from experiments upon liv- 
ing animals, where the abdominal muscles are laid open, and 
from cases in which the stomach has lain in the thorax, and 
yet been excited to active vomiting.* Again, it is equally evi- 
dent that, when the stomach is excited to vomiting,there is con- 
sent of the abdominal muscles, by which they are brought into 
violent and spasmodic action ; not alternating in their action, 
as in the motion of respiration, but acting synchronously, so as 
greatly to assist in compressing the stomach : but at the same 
time, the action of these muscles, however forcible their con- 
traction, cannot alone cause vomiting ; nor has this action any 
tendency to produce such an effect on other occasions, in which 
the utmost contraction of the diaphragm and abdominal mus- 
cles is required to the compression of the viscera. Many have 
conceived that vomiting is entirely the effect of the action ol 
the abdominal muscles and diaphragm. Such, for example, 
has been the opinion not only of J. Hunter, but of Duverney, 
and of M. Chirac in Hist, de 1’Acad. de Sciences, 1700. M. 
Littre opposed this notion, and contended before the Aca- 
demy, that the contraction of the diaphragm was the principal 
cause of vomiting. M. Lieutaud in 1752 supported the idea 
that vomiting is the effect of the action of the stomach. He 
OF THE STOMACH. 
* See Wepfer de Cicuta Aquatica, p. 68.—Sauvagc’s Vomitus. OF THE STOMACH. 
209 
found, upon dissection, in a patient whose stomach had re- 
sisted every kind of emetic, that it was greatly distended and 
become insensible; and concluded that the want of action in 
the stomach, and consequent loss of the power of vomiting, 
was a strong proof of the action being the effect of the con- 
traction of the stomach only. There are other more curious 
instances of disease of the stomach preventing the muscular 
contraction in any violent degree, and consequently the ab- 
sence of the usual symptom of vomiting:—an instance of this 
kind will be seen in Dr. Stark’s work. In my Museum I have 
a preparation of a stomach, in which the walls had become so 
thick that they could no longer suffer contraction bv the mus- 
cular fibres; the consequence of which was, that although the 
inner coat of the stomach was in a raw and ulcerated state, 
there was no active vomiting. 
There is a very curious experiment by M. Magendie which 
has much puzzled men’s minds. He cut out the stomach of 
a large dog, and substituted in its place a bladder which he 
fastened to the oesophagus, and having excited vomiting, by 
pouring emetic solution into the veins, the contents of the 
bladder were discharged as from the natural stomach. The 
conclusion has been too hastily formed, that the stomach has 
therefore nothing to do with the action of vomiting. But it 
ought to be recollected, that the bladder represents a relaxed 
stomach, whereas the stomach is muscular and active, and ca- 
pable of resisting the action of the. abdominal muscles and dia- 
phragm, unless there be a consent of the action of the sto- 
mach and the action of the muscles of respiration. Thus if 
we could suppose that a man had a distended bladder for a 
stomach, whilst he exerted himself forcibly and retained his 
breath the contents would be discharged. So would they if 
he lay with his belly over a yard-arm. But no such discharge 
takes place from the natural body, because the upper orifice 
of the stomach resists! This resistance does not take place 
in vomiting; and therefore, I say, the stomach has to do with 
vomiting, in spite of all the cruelties which have been com- 
mitted. ' 
The singultus is the partial exertion of the sympathy betwixt 
the upper orifice of the stomach and the diaphragm, by which 
a kind of wTeak spasmodic action is excited in it, but without 
a concomitant inverted action in the stomach and (esophagus. 
It is a convulsive and sonorous inspiration, owing to an irrita- 
tion of the upper orifice of the stomach and oesophagus, but 
not exactly of that kind which causes inversion of the natural 
actions of the stomach. Thus we have the singultus from, 
gluttonous distention of the stomach, from some medicines 210 
OE THE STOMACH. 
and poisons, from some crude aliment, or even from some 
foreign body sticking low in the oesophagus, or from inflam- 
mation. The borborygmi and rumination seem to be gentler 
inverted actions of the upper orifice of the stomach and 
oesophagus, unassisted by any great degree of compression of 
the stomach by tin* abdominal muscles and diaphragm. 
The full action of vomiting is preceded by inspiration, which 
seems a provision against the violent excitement of the glottis, 
and the danger of suffocation from the acrid matter of the 
stomach entering the wind-pipe ; for by this means the ex- 
piration and convulsive cough accompanying or immediately 
following the action of vomiting, frees the larynx from the 
ejected matter of the stomach. But the action of the dia- 
phragm is farther useful by axting upon the mediastinum, 
which embraces the (esophagus, and no doubt supports it in 
this violent action. 
The subject is very interesting, but I must enlarge no more 
upon it here. 
NERVOUS OR VASCULAR COAT OF THE STOMACH. 
What Haller calls the nervous coat, is the cellular structure 
in which the vessels and nerves of the stomach ramify and 
divide into that degree of minuteness which prepares them for 
passing into the innermost or villous coat. It may with equal 
propriety be called the nervous, the vascular, or the great cel- 
lular coat.* Taking it as the thii'd distinct coat of the sto- 
mach, it is connected with the muscular coat by the second 
cellular coat, and with the villous coat by the third cel- 
lular coat. Strictly, however, it is the same cellular mem- 
brane, taking here a looser texture to allow of the free inter- 
change and ramification of vessels. When macerated, it 
swells and becomes like fine cotton, but has firmer and apo- 
neurotic-like filaments intersecting it; it can be blown up so 
as to demonstrate its cellular structure.! It is in this coat 
that anatomists have found small glandular bodies lodged, 
especially towards the extremities or orifices of the stomach. 
Villous coat.—This is the inner coat, in which the vessels 
are finally distributed and organized to their particular end. 
It is of greater extent than the outer coats of the stomach; 
which necessarily throws it into folds or plicae. These folds 
take, in different animals, a variety of forms: but they arc 
* To call it cellular coat, however, would be to confound it with the three 
cellular coats generally enumerated by authors. 
! Winslow, sect. viii. p. 64, OF THE STOMACH. 
211 
simple in man ; from the oesophagus they are continued in a 
stellated form upon the orifice, but form no valve here. In 
the body of the stomach they are more irregular, sometimes 
retiform, and sometimes they form circles or squares, but they 
have generally a tendency to the longitudinal direction. In 
the pyloric orifice the villous coat forms a ring, called the 
valve of the pylorus, which, however, has no resemblance to a 
valve in its form or action. This ring is not formed bv the 
inner coat of the stomach alone, but by the inner stratum of 
fibres of the muscular coat, the vascular and cellular coats, and 
the inner or villous coat. The effect of all these coats, re- 
flected inward at the lower orifice, is to form a tumid and pretty 
thick ring, which appears like a perforated circular membrane 
when the stomach has been inflated and dried ; but in neither 
state is its direction oblique so as to act as a valve. It seems 
capable of resisting the egress of the food from the stomach, 
or the return of the matter from the duodenum, merely by 
the action of the circular fibres which are included in it. 
In the inner surface of the stomach of those dying suddenly, 
and who were previously in health, plicx may be observed 
more or less distinct, according to the state of contraction of 
the muscular coat of the stomach. But in those dying of 
disease and with relaxed stomach, no folds of the inner coat of 
the stomach are to be seen. 
The glands of the human stomach are very small, but in 
great numbers around the termination of the oesophagus. In 
this description I am looking to the plate of Sir Everard Home. 
Brunner described the glands of the stomach as seated on the 
curvatures. Glands are distinctly to be seen in the stomach 
of birds and many quadrupeds, and in fishes and serpents, 
(Haller.) But it is to Sir Everard Home that we owe the most 
careful observations on this subject. His lectures on this 
subject, delivered in the College of Surgeons, had that grave 
character of investigation befitting the place, while they pos- 
sessed an interest beyond example.* 
Gastric fluid.—There is secreted into the stomach a fluid, 
which is the chief agent in digestion. The most common 
opinion is that it flows from the extreme arteries of the villous 
coat in general, partly from the glands. When pure, it is a 
pellucid, mucilaginous liquor, a little salt and brackish to the 
taste, like most other secretions’ and having the power of re- 
tarding putrefaction and dissolving the food. It acts on those 
substances which are nutritious to the animal, and which are 
peculiarly adapted to its habits. 
* These lectures are now published 212 
OF THE STOMACH. 
It seems to be a peculiarity in the human stomach, that it 
has a greater capacity of digesting a variety of animal and 
vegetable bodies. But I should at the same time conceive 
that the natural power of digesting the simple and appropriate 
food is diminished as the.stomach gains the power of dissolv- 
ing a variety of substances.* In other creatures, a sudden 
change of food is rejected, and the powers of the stomach are 
found incapable of acting duly on the aliment, though time so 
far accommodates the gastric fluid to the ingesta, that the ani- 
malization becomes perfect. Mr. Hunter speaks of the power 
of cattle eating and digesting their secundines.f I have seen 
the membranes coiled in the bowels of a cow; but I too hastily 
concluded this to be the cause of death. I am corrected by 
the authority of Dr. Jenner and Dr. Adams. The fact is suf- 
ficiently ascertained, that the nature of the digestive process 
may be so far altered that graminivorous animals may be made 
to eat flesh, and carnivorous animals brought to live upon vege- 
tables. This throws us back from the simple idea which we 
should be apt to entertain of the nature of the change produced 
by digestion, viz. that it is simply chemical. For we see that 
the nature of the solvent thrown out from the stomach, and its 
chemical properties, may be changed by an alteration in the 
action of the coats of the stomach. Thus we are baffled in 
our inquiries, and brought back to the consideration of this 
living property,* which can so accommodate itself to the nature 
of the aliment. 
The gastric fluid has been collected from the stomachs of 
animals after death, by sponges which the animal has been 
made to swallow, or which have been thrust down into its 
stomach, incased in perforated tubes. And, lastly, it has been 
obtained by exciting the animal to vomiting, when the stomach 
was empty ; for the secretions of the stomach are then poured 
out unmixed with food.j; Although by these means a fluid 
may be obtained which may properly be called the succus gas- 
tricus, yet it must contain a mixture of the saliva, and secretions 
from the glands of the (esophagus and pharynx, with the 
glandular secretions of the stomach, and the general vascular 
secretion from the surface of the stomach. It is a fluid, 
then, upon which the chemist can operate with no hope of 
* Dr. Adams’s experiments go to prove that the gastric juice is always the 
same. An early friend of mine, Dr. Cheyne, whose works on the diseases of 
children have sufficiently proved his minuteness and accuracy of observation, 
lately told me, that on the principle here expressed he has been very success- 
ful in humouring the delicate stomachs of his patients; he has found that two 
kinds of food received at once into the stomach will be rejected; when 
separately, they will not disorder the stomach. 
Observations on Digestion. 
• By Spallanzani, OF THE STOMACH. 
213 
a successful or uniform result. And, indeed, chemistry seems 
no farther to assist us in forming an accurate conception of the 
changes induced upon the fluids in the alimentary canal, than 
that the more perfect, but still very deficient, experience of the 
modern chemist successfully combats the speculations of the 
chemists of former ages. For example, it was formerly sup- 
posed that digestion was a fermentation, and that this fermen- 
tation was communicated and propagated by the gastric juice. 
It is now found that the gastric juice has properties the reverse 
of this ; that it prevents the food from taking an acid or putre- 
factive fermentation; that its acts by corrodingand dissolving 
the bodies received into the stomach; and that it is itself at 
the same time converted into a new fluid, distinct in its pro- 
perties.* It is almost superfluous to observe,! that the gastric 
juice has no power of acting upon the coats of the stomach 
during life ; whether this be owing to the property in the living- 
fibre, of resistance to the action of the fluid, or that there is a 
secretion bedewing the surface, which prevents the action, it is 
not easy to say; but more probably it is owing to the resist- 
ance to its action inherent in a living part-! 
Mr. Hunter supposed it necessary that the animal should be 
in health, immediately preceding death, in order that the se- 
cretion of the gastric juice may be natural and capable of dis- 
solving the dead stomach : but I have found the stomach of 
children, who have died after a long illness, digested by the 
secretion of the stomach. See Examples in my Collections. 
Or digestion.—By trituration and mastication, and the 
union of the saliva with food in the mouth, it is prepared for 
the more ready action of the stomach upon it. No farther 
* The most curious fact is that property of the coats of the stomach, or of 
the fluids lodging in the coats of the stomach, by which milk and the se- 
rum of the blood are coagulated. It has been found that a piece of the sto- 
mach will coagulate six or seven thousand times its own weight of milk. This 
action seems a necessary preparation for digestion, which shows us that the 
most perfect and simply nutritious fluid is yet improper, without undergoing 
a change to be received into the system of vessels. For example ; milk and 
the white of eggs are first coagulated, and then pass through the process of di- 
gestion. See J. Hunter, Animal Economy, Observations on Digestion. 
f I do think it a very self evident fact, notwithstanding Dr. Adams’s taunting 
manner of quoting these words. See that very interesting work on Morbid 
Poisons, preface, xxxvi. 
+ Mr. Hunter is one great authority on this subject, &c. 
See also Morgagni Advers. III. A. XXIV. 
Dr. Adams on Morbid Poisons, preface,and Mr. A. Burns’s, of Glasgow, paper. 
F.din. Journal, Ap. 1810. Amongst other curious facts stated by Mr. Burns is 
this, that he has found all the length of the alimentary canal dissolved into a 
pulpy glutinous mass. I may say that, connected with the discussion, there 
may enter a question as to what is the cause of a tenderness sometimes to be 
observed in all the membranes of the body. I have to-day examined the vis- 
cera of a negro, where the intestines were particularly tender, but the peri- 
cardium and valves of the heart more remarkably so still. 214 
OF THE STOMACH. 
change is induced upon it than the division of its parts. Biu 
in the stomach, the first of those changes (probably the most 
material one) is performed, which by a succession of actions 
fits the nutritious matter for being received into the circulation 
of the fluids of the living body, and for becoming a component 
part of the animal. For now the gastric juice acting on this 
fluid mass quickly dissolves the digestible part, and entering 
into union with it produces a new fluid, which has been called 
chyme, a thick or viscid and turbid fluid. The mass has 
changed its sensible and chemical properties ; it has suffered 
the full action of the stomach, and by the gradual and succes- 
sive muscular action of the stomach it is sent into the duode- 
num. ,The food is converted into chyme by the operation of 
the gastric fluid, by an operation peculiarly animal, a process 
of life. And the conversion of the food into a new substance 
is unattended by any chemical change, strictly speaking, if by 
chemistry we understand the mutual influence of dead matters 
in forming compounds or separating and extricating the con- 
stituent parts. Animal or vegetable matter in the heat and 
moisture of the stomach would quickly fall into the fermenta- 
tions ; but the living property of the stomach prevents this. 
In this I speak of the stomach in health ; when weak, then the 
symptom announcing the diminished power is the extrication 
of gas, or the formation of acids, with oppression and uneasy 
sensations. The contents of the stomach consist of air (partly 
swallowed, partly extricated by chemical change,but still more 
in all probability by the heat,) of chyme; and of a grosser part 
incapable of becoming nutritious, and the separation of which 
from the chyme is accomplished by the action of the canal. 
Now the stomach being stimulated by fulness, by flatus, and 
more still by the peculiar irritation of the food prepared by 
digestion, the muscular coat is brought into action, and the 
contents of the stomach delivered into the duodenum. 
A case is on record which finely illustrates the function of 
the stomach. A woman, presented in the clinical ward of La 
Charite, to Corvisart, who had a fistulous opening in the left 
side of the epigastric region, which communicated with the 
stomach, and through which part of the villous coat of the sto- 
mach could be seen, of a vermilion colour, and covered with 
mucus, and having certain plicae. 
The vermicular undulations of these rugae of the inner coat 
of the stomach could be observed. Three or four hours after 
this woman took food, she felt an irresistible desire to raise 
the dressings from the fistula. Then flatus wras forcibly dis- 
charged with the food, which was reduced into a greyish pulp, 
having neither acid nor alkaline properties. After emptying 
the stomach., which she washed by sending through it a pint OE THE STOMACH. 
215 
of infusion of chamomile, she found perfect ease. In the morn- 
ing a small quantity of fluid like saliva, ropy and clear, was 
found at the orifice. This was probably the gastric fluid ; it 
possessed neither acid nor alkaline qualities. 
On her death the hole in the stomach was found eight fin- 
gers bireadth from the left extremity, or one third of the whole 
length of the stomach distant from the pyloric orifice. 
From this case we learn, 1. that the stomach is subject to a 
gentle vermicular motion; 2. that the food received into the 
stomach is retained three or four hours in the great left extre- 
mity of the stomach ; 3. that when it has undergone the process 
of digestion there, it is conveyed, with rather a sudden impulse, 
into the pyloric extremity of the stomach ; 4. that the chyme 
thus formed, has undergone an animal process, becoming 
neither acid nor alkaline. Contemplating this illustration of 
the function of the stomach as a digesting organ, with the ac- 
cording action of its muscular fibres above described, a solid 
ground-work is afforded for the pathology of this organ. 
Hunger and thirst. We are solicited to take food by the 
uneasy sensation of hunger, and by the anticipation of the vo- 
luptuous sating of the appetite, and by the pleasures of the 
palate. Hunger is considered as the effect of the attrition of 
the sensible coats of the stomach upon each other by the peris- 
taltic motion of the stomach and compression of the viscera. 
This appears to be too mechanical in explanation. If the sen- 
sation proceeded merely from such attrition of the coats of the 
stomach, food received into the stomach would be more likely 
to aggravate than to assuage the gnawing of hunger; to excite 
the action of the stomach would be to excite the appetite, and 
an irritable stomach would be attended with a voracious de- 
sire of food. Something more than mere emptiness is required 
to produce hunger. By some, hunger is supposed to proceed 
from the action of the gastric fluid on the coats of the stomach, 
by others it is attributed to the dragging of the liver, now no 
longer supported by the full stomach. Hunger is like thirst, 
a sense placed as a guard, calling for what is necessary to the 
system, and depending on the general state of the body. Mor- 
bid craving may proceed from many causes ; a tape worm 
has occasioned bulimia, and spirits and high seasoning excite 
the appetite even when the stomach is full. 
Thirst is seated in the tongue, fauces, oesophagus, and sto- 
mach. It depends on the state of the secretions which bedew 
these parts, and arises either from a deficiency of secretion, or 
from an unusually acrid state of it. It would appear to be 
placed as a monitor calling for the dilution of the fluids by 
drink, when they have been exhausted by the fatigue of the 
hody and by perspiration, or when the contents of the stomach 216 
OF THE STOMACH. 
require to be made more fluid—the more easily to suffer the 
necessary changes of digestion. 
The change on the secretion of the tongue and fauces from 
disorder of the stomach, is not, I imagine, a consequence of an 
influence communicated along the continuous surface. It has 
its origin in this natural constitution of the parts ; this connec- 
tion which nature has established betwixt the stomach and 
tongue, betwixt the appetite and the necessity of the system. 
The state of the tongue, the loose or viscid secretions of the 
throat and fauces, even the secretion of the saliva, the irritabi- 
lity of the larynx, are influenced by the stomach. The more 
permanent and demonstrable effects on the tongue are princi- 
pally attended to ; which perhaps is the reason that we only 
know by this that the stomach is not how it is af- 
fected. 
The cardiac orifice is the chief seat of all sensations of the 
stomach, both natural and unusual, as it is the most sensible 
part of the stomach. Indeed we might presume this much by 
turning to the description and plates of the nerves ; for we shall 
find that this upper part of the stomach is provided in a pecu- 
liar manner with nerves, the branches of the par vagum. 
The sympathy of the stomach with the rest of the intestinal 
canal, the connection of the head and stomach in their affec- 
tions, the effect of the disorder of the stomach on the action of 
the vascular system and of the skin, and the strict consent and 
dependence betwixt the stomach and diaphragm and lungs, 
and in a particular manner with the womb, testicle, &c.—and 
again, the connection of the stomach with the animal economy, 
as a whole,—must not escape the attention of the student of 
medicine. 
SECTION III. 
OF TIIE INTESTINES. 
That portion of the alimentary canal which extends from 
the lower orifice of the stomach to the anus is called the intes- 
tines. It is divided into the small intestines, and the great in- 
testines ; the small intestines are divided into the duodenum, 
jejunum, and ileon. The great intestines are divided into 
caecum, colon, and rectum. 
The marked difference of function is betwixt the small in- 
testines and the great intestines. But betwixt the form and 
capacity of the stomach, the form and capacity of the small in- OF THE SMALL INTESTINES. 
217 
testines, and the form and capacity of the great intestines, there 
is always a certain relation preserved in the different classes of 
animals. 
The small intestines are estimated to be in length 26 feet, 
or from four to five times the length of the body,and the great 
intestines one length of the body, or about six feet. The 
younger the subject, the longer the intestinal canal. In an in- 
fant they were found to be upwards of eleven times the length 
of the body. In a child of one foot nine inches they were up- 
wards of eight times the length of the body. In a child three 
feet one inch they were found to be seven times and one half 
the length of the body.* 
Is this difference to be accounted for by supposing that a 
different food is applicable to the several ages, or is it an in- 
crease of absorbing surface accommodated to the necessities 
of the body while growing. 
In the carnivorous animal the whole of the canal is shorter, 
being about live times the length of the animal, for example in 
the lion. In the herbivorous animalsthe intestines are longer 
and more complicated, affording means for the retention or the 
delay of the descent of the food. 
Of the small intestines the first portion is division ex- 
tending from the orifice of the stomach til1 d ls encumbered 
in the mesocolon. It is improperly calk’d the duodenum. 
THE DUODF’'*1™ 
Stands distinguished from *-ne general tract of the small in- 
testines by its shape, conq^lons and situation. It has been 
called duodenum, became it: was usual to measure its extent 
by the breadth of twelve lingers. It is greatly larger than any 
other part of th* small intestines; irregular and sacculated; 
more fleshy > and, although it has fewer plicae, it is more gland- 
ular and ’tore vascular; but its greatest peculiarity, and that 
which must convince us of its importance in the animal eco- 
nomy, and of the necessity of attending to it in disease, is this, 
that it is the part which receives the biliary and pancreatic 
ducts, and in which a kind of second stage of digestion takes 
place. The intestine takes a course acroSs the spine from the 
orifice of the stomach. First it goes in a direction downward; 
then it passes upward till it touches the gall bladder; then 
making a sudden turn it descends directly near to the right 
kidney, and is then involved in the lamina of the mesocolon: 
it then takes a sweep towards the left side, obliquely across the 
* Sir Eyerard Home’s Lectures. 218 
OF THE SMALL INTESTINES. 
spine and a little downward; from this description it is obvious 
that it must be longer than the breadth of twelve fingers, and 
indeed I call duodenum all that portion of the intestines which 
is above the mesocolon, preferring a natural to an arbitrary 
boundary.* As in this extent, besides being tied down to the 
spine by the mesocolon, it has the peritoneum, reflected off 
from it at other points, we have to remark the ligamentum due- 
deno-renale, ligamentum duodeno-hepaticum already described. 
Although we shall presently treat of the coats of the small 
intestines in general, yet it may not be improper here to ob- 
serve what are announced as peculiarities in the coats of this 
first division. The first or peritoneal coat is imperfect, as must 
already be understood: for it does not invest the whole circum- 
ference of the gut ; it ties it down more closely, or it merely 
contains it in its duplicature, Avhile a greater profusion of cellu- 
lar membrane accompanies this than the other divisions of the 
intestines. The muscular coat is stronger than that of the 
jejunum and ileon; the plies formed by the inner coats, smaller 
than those of the other part of the small intestine, and having 
more of a glandular structure. At the lower part of the first 
incurvation of the duodenum, the inner coat forms a particular 
process like ko those which are called valvulae conniventes; and 
in this will be discovered the opening of the biliary duct, within 
which also the duc Jls pancreaticus generally opeiis. 
It is not without stLrie reason that anatomists have consider- 
ed the duodenum as a s^oncj stomach, calling it ventriculus 
secunclus, and succenturia„is . for there is here performed 
a change upon the food, con.Vv^jng the chyme (as they have 
chosen to call it,) which is the stomach, into perfect 
chyle. But to suppose that the ch;nie \s perfected in the 
duodenum, is to suppose the biliary and t picreatic secretions 
necessary to the formation ol chyle ; a p«dnt which is not 
allowed ; for many suppose that the bile is me*«lv a stimulus 
to the intestines, holding a control over their motions; others, 
that it is useful only in separating the chyle from tht excre- 
ment; or again, that the bile is decomposed, part entering Vto 
the composition of the chyle, while the other goes into that of 
the faeces ; it seems to bestow upon them a power of stimulat- 
ing the intestinal canal in a greater degree ; and as the chyle 
is formed occasionally without the presence of bile, we may 
be induced the more readily to allow that the bile does not, in 
* Ruysch calls it “ Intestinum digitale, vel intestinum rectum brevissimum.” 
Adversar. Anat. Decad. II. 
See a good description of the duodenum by M. Laurent Bonazzoli, in the 
Transactions of the Academy of Bologna. And the Dissert. L. Claussen, de 
duodeni situ et nexu. Sandifort Thes, V. III. Monro, Medical Essays. OP THE SMALL INTESTINES. 
219 
the natural actions and relations of the system, enter into the 
composition of the chyle. At all events, we see that it is the 
bile which is the peculiar stimulus of the intestinal canal, and 
that when interrupted in its discharge from the ducts, the mo- 
tions in the belly are slow, and costiveness is the consequence. 
There are poured into the duodenum, from the liver and 
pancreas, secretions which have an extensive' effect on the 
system of the viscera; and we must acknowledge that the de- 
rangement of these secretions must operate as a very frequent 
and powerful cause of uneasiness, and therefore that the duo- 
denum must often be the seat of uneasy and distressing symp- 
toms. We may observe that, from the course of the duode- 
num, pain in it should be felt under the seventh or eighth rib, 
passing deep, seeming to be in the seat of the gall bladder, and 
stretching towards the right hypochondrium, and to the kid- 
ney, and again appearing as if on the loins. We may observe 
farther, that from the connections of this portion of the intes- 
tine, and from the manner in which it is braced down by the 
mesocolon, spasm, when flatus is contained in it, will some- 
times produce racking pains. Nay farther, when the irregu- 
larities of digestion affect the duodenum, and spasm and 
digestion follow ; the distention causes it to press upon the 
gall-bladder, and the pressure and excitement together cause 
an irregular and often an immoderate flow of bile, which with 
the acrid state of the food produces anxieties and increased 
pain, inverted motion, and vomiting. 
We must not forget, that the inverted action of the stomach 
draws quickly after it the inverted motion of the duodenum. 
It may be of consequence to attend to this in the operation of 
an emetic, for the stomach will sometimes appear to be dis- 
charging foul and bilious matter which we naturally may sup- 
pose to have been lodged in it, but which has actually flowed 
from the duodenum, or has even come recently from the ducts 
in consequence of the operation of the vomit.* 
From a defect in the natural degree of the stimulating power 
of the bile, it will accumulate in the duodenum, occasioning 
anxiety and loss of appetite, and even congestion of blood and 
a jaundiced skin; we may certainly affirm that these at least 
are often connected. Such accumulation in the duodenum 
must be attended with a languid action of the whole canal, and 
inactivity of the abdominal viscera, because the peristaltic mo- 
tion is begun here in the natural action of the intestines; and 
* Indeed vomiting in consequence of concussion and compression upon the 
whole contents of the abdomen, and in a particular manner on the liver, 
affords most powerful means of operating upon the infarction and remora of 
the blood in the hepatic system. 220 
OF THE SMALL INTESTINES. 
if the proper stimulus be deficient here, so must it be in the 
whole system of the viscera. Hence the necessity of rousing 
the activity of the liver by evacuating the whole canal. 
I may further observe, that it has been the opinion of the 
most respectable old physicians, those whose knowledge of 
diseases has been drawn from an acquaintance with anatomy, 
from the frequent inspection of dead bodies, and the obser- 
vation of the symptoms during life, that the study of the 
diseases connected with the duodenum is the most important 
which can occupy the attention of the medical inquirer.* 
OF THE JEJUNUM AND ILEON. 
The small intestines, under the name of jejunum and ileon, 
occupy the space in the middle and lower part of the abdo- 
men, the great mass forming convolutions in the umbilieal re- 
gion. The canal of the small intestines is gradually and im- 
perceptibly diminished in diameter as it is removed from the 
lower orifice of the stomach ; so that the termination of the 
ileon in the caput coli is considerably smaller than the duode- 
num. This tract of the small intestines performs the most im- 
portant function of the chylopoietic viscera (if any can be said 
to be peculiarly important where the whole is so strictly con- 
nected ;) for here the food is moved slowly onward through a 
length of intestine four times the length of the body, and 
exposed to a surface amazingly extended by the pendulous 
and loose duplicatures of the inner coat. Here the feces arc 
gradually separated from the chyle, and the chyle adhering 
to the villi is absorbed and carried into the system of vessels. 
The jejunum! is the upper portion of the small intestine. 
Its extent is two-fifths of the whole. Its convolutions are 
formed in the umbilical region. • 
The ileon lies in the epigastric and iliac regions, surrounds 
the jejunum on the sides and lower part, and forms three-fifths 
of the whole extent of the intestine from the mesocolon to the 
valve of the colon. The coats of the ileon are thinner and 
paler; the valvular projections of the inner coat less conspi- 
cuous; and the mucous glands become more .apparent in the 
lower portion. 
There is sometimes found a lusus in the lower part of the 
ileon before it passes into the colon; a blind pouch or caecum 
is, as it were, attached to the ileon, resembling the caput coli. 
I have found many instances of this, and several specimens 
* See Sandifort, vol. iii.p. 288. See Hoffman, 
f So named from its being' more generally empty. OF THE SMApL INTESTINES. 
221 
majr be seen in my collection. Sometimes there is more 
than one csecum in the course of the ileon.^ 
THE PERITONEAL COAT AND MESENTERY. 
The peritoneal coat of the small intestines is of the same 
nature with that of the stomach. It is thin, smooth, ancl pos- 
sessing a certain degree of elasticity. On the surface it has a 
moisture exuding from its pores ; and it firmly adheres to the 
muscular fibres beneath by a very dense cellular substance. 
Its transparency makes the muscular fibres, blood-vessels, and 
lymphatics easily distinguishable ; and when it is dissected or 
torn up, the longitudinal muscular fibres will be found in gene- 
ral attached to it. Its use is tp give a smooth surface and to 
strengthen the intestine, and in a great measure to limit the 
degree ol their distention. 
The peritoneal coat of the intestine is continued and re- 
flected off upon the vessels and nerves which take their course 
to the intestine ; or, what is the same thing, and indeed is the 
more common description, the two lamina of the peritoneum 
which form the mesentery, after proceeding from the spine 
and including the vessels, nerves, and glands belonging to the 
tract of the intestine, invest the cylinder of the intestine under 
fhe name of peritoneal coat.f 
The mesentery is composed of membranes, glands, fat, and 
the several systems of vessels, arteries, veins, lacteals, afkl 
nerves. As in reality it is a production of the peritoneum, it 
may be said to arise from the mesocolon, or the mesocolon 
from the reciprocally. But at present we may 
trace the mesentery .from the root of the mesocolon—for the 
jejunum, emerging from under the embrace of the mesocolon, 
carries forward the peritoneum with it; and the lamina of the 
peritoneum, meeting behind the gut, include the vessels which 
pass to it and from the mesentery. This connection of the 
small intestines by means of the prolongation of the perito- 
neum, while it allows a considerable latitude of motion, pre- 
serves the convolutions in their relations, and prevents them 
from being twisted or involved. But it is by the walls of the 
abdomen that the intestines, as well as the more solid viscera, 
are supported ; for when the bowels escape by awound, apor- 
* The appendices cscales of the ileon have given birth to a curious ques- 
tion in the pathology of hernia. See “ Hernia ab ilii diverticulo.” Morgagni, 
Adv. Anat. III. “ Hernie formce, par l’appendice de l’ileon.” Lettrk, Mem. 
de l’Acad. Royale des Sciences, an. 1700 Iluysch, Palfin, Sec. See cases ot 
anus at the groin in the Museum, 
f See Plate 1.5, 6,7, S. 222 
OF THE SMALL INTESTINES. 
tion of an intestine will hang down upon the thigh, unrestrained 
by the connection with the mesentery. 
The mesentery begins at the last turn of the duodenum, or 
beginning of the jejunum. Its root runs obliquely from left to 
right across the spine. Here it has consequently no great ex- 
tent ; but as it stretches toward the intestines, it spreads like a 
fan, so that its utmost margin is of very great extent, being- 
attached to a portion of the canal, which we have estimated at 
four times the length of the body. In the middle of the small 
intestine, the mesentery has its greatest extent or breadth ; 
towards the beginning of the duodenum and the termination 
of the ileon, it is shorter, and more closely binds down the 
intestine. 
MUSCULAR COAT OF THE INTES TINES. 
The peritoneum is united to the muscular coat by a very 
delicate and dense cellular membrane ; which in the enume- 
ration of the coats we must call the first cellular coat, but which 
really does not deserve the name of a distinct coat; for, as 
already said, the outer lamina of the muscular coat is raised 
with the peritoneum, and adheres intimately to it. The fibres 
of the muscular coat of the intestines are simpler than those of 
■the stomach ; for here there are only two sets of fibres, the 
longitudinal and circular fibres. The outer stratum consists 
of the very minute and delicate longitudinal fibres. Indeed, 
when the system has been exhausted by a long and debilitat- 
ing illness, with scarcely any excitement of the intestinal 
these fibres are not to be observed. In a man who 
has been cut suddenly off by disease, or who has died a vio- 
lent death, they become more demonstrable ; and in diseases 
where there has been congestion and excited action in the in- 
testines, they are of .course still stronger and more discernible. 
The internal stratum of the muscular fibres is much stronger 
and more easily demonstrated. These fibres will be observed 
much stronger about the duodenum and upper part of the 
jejunum, but they become weaker and more pellucid towards 
the extremity of the ileon. Tracing any particular fibre of 
the circular stratum, it is found to form only a segment of a 
circle, a part of the circuit of the intestine. It seems lost 
amongst neighbouring fibres or cellular connections ; but still, 
taken together, the circular muscular fibres uniformly sur- 
round the whole gut.* 
To account for that action of the intestines which urges on 
* Morgagni Adversaria Anatomies III. Animadversio V. OF THE SMALL INTESTINES. 
223 
the food, we may suppose a greater degree of irritability and 
activity to reside in the upper portion, where of course is com- 
menced that action which is successively propagated down- 
wards, carrying the faeces into the lower part of the canal. 
Some anatomists have ingeniously imagined that the inner 
stratum of fibres surrounds the intestine, not in a circular di- 
rection, as was asserted by Willis, but obliquely and in a spiral 
course; from*which followed a simple explanation of their 
effect, since the contraction of the fibre winding lower in the 
intestine, pursued the contents with a uniform, progressive 
constriction. 
Physiologists have made a distinction in the motion which 
they have observed in the intestines of living animals. The 
one they call the vermicular, and the other the peristaltic 
motion. Upon looking into the belly of a living animal, or of 
one newly killed, there may be observed a motion among the 
intestines, a drawing-in of one part and a distention and elon- 
gation of another part of the convolution. This motion has 
some resemblance to the creeping undulating motion of a 
reptile, and has got the name of vermicular motion. On the 
other hand, the direct contraction of the gut by the constric- 
tion of the circular fibres is the peristaltic motion. We must 
not however allow ourselves, from the loose expressions of 
authors, to imagine that these circular straight fibres act se- 
parately ; on the contrary, excited by the same stimulus, they 
have a simultaneous motion to the elfect of accomplishing 
the perfect contraction of the gut and motion of its contents.* 
While the stimulus is natural, the contraction of the muscu- 
lar coat is in a regular series from above downward, and, the 
lower part contracting before the upper is completely relaxed, 
the food must be urged downwards into the lower portion. 
Nay, I should imagine that the lower portion becomes relaxed 
at the same time that the upper portion is contracted.f 
ANTI-PERISTALTIC MOTION. 
When the successive contraction of the muscular fibres of 
the intestines is opposed in its natural course downward, either 
* Neither can I allow that the acting of the longitudinal fibres in one por- 
tion of an intestine dilates that which is below, otherwise than through the 
compression of food and flatus. 
-j- From the experiment of Haller and of others, it is proved that the irritabi- 
lity of the intestines long survives that of the heart; that the intestines are in 
general in lively motion, when no motion can be observed in the stomach; 
but that sometimes the motion of the stomach continues longer than that of 
the intestines. It is proved also that the action of the intestine is adequate to 
the motion downward and the discharge of faeces, without the aid of the 
abdominal muscles. See Mem. par Haller svr les Mouvemens des Intestines ; and 
Opera Minora, p. 393. 224 
OF THE SMALL INTESTINES. 
by a violent stimulus (the effect of which is to cause a more 
permanent contraction in the coats, and one which does not 
readily yJfeld to the relaxation that follows, as in the natural 
contraction,) or when there is a mechanical and obstinate in- 
terruption to the contents of the bowels ; then is the natural 
action reversed. This anti-peristaltic motion arises thus; a 
portion of the intestine being constricted, and not yielding to 
the contraction which, in the natural action of the gut, should 
follow in order, the motion of the gut must be stationary for a 
time, until the part above that which is contracted becomes 
relaxed; then the contents of the intestine finding a free pas- 
sage upwards, and that portion contracting and propelling the 
matter still upwards and retrograde, (since it is opposed by the 
contraction below,) a series of retrograde or anti-peristaltic 
motions are begun and propagated. The course of the action 
being changed, the contraction of the gut is not followed by the 
dilatation of the portion below, but by that above. By this 
means the matter of the lower portion of the intestinal canal 
is carried into the upper part, and there acting as an unusual 
stimulus, it aggravates and perpetuates the unnatural action. 
Nay, from experiments it appears that a permanent irritation 
will cause an accelerated motion in both directions; that from 
the point stimulated there will proceed downward the regular 
series of contractions and dilatations, while the motion is sent 
upwards and retrdgrade from the same point of the intestine 
toward the stomach.* And this observation, the exhibition ol 
medicine and the diseases of the intestines confirm. But 
farther we may observe, that the food is not uniformly moved 
downward; it is shifted and agitated by an occasional retro- 
grade motion thus: 
*'Haller, loc. cit. Exper. 424. OF THE SMALL INTESTINES. 
225 
The portion of the intestine included under A contracts and 
sends its contents into B. B contracting sends its fluid contents 
in part backward into A, but in a greater proportion into C. 
While the contents of the middle portion are sent into the 
lower part in a greater proportion than into the higher divi- 
sion, the tendency of the food will be in its natural course, 
downward ; whilst at the same time it suffers an alternate 
motion backward and forward; so that it is more extensively 
applied to the absorbing surface of the intestines. 
The stimulus to the intestines is matter applied to their inner 
coat: and although there is much sympathy in the whole 
canal, yet unless there be matter within a portion of the 
canal, that particular part has little action. Accordingly, when 
there is obstruction to the course of the aliment, by whatever 
cause it may be produced, the portion below becomes shrunk 
and pale, and free from the effects of inflammation; while 
that stimulated by the food, being in a high state of excite- 
ment, irritated by the presence of matter which it is unable to 
send forward, evacuated only partially by an unnatural and 
highly excited retrograde action, it becomes large, thick in its 
coats, strong in its muscular fibres, and greatly inflamed, till 
it terminates at last in gangrene.* 
The unusual excitement of the muscular fibres produces a 
very curious effect in the intus-susceptio, or the slipping of one 
portion of the gut within another. This may be done by ap- 
plying acrid matter to the intestines of living animals ; and I 
have no doubt that it has been produced by giving purges too 
strong and stimulating in cases of obstruction of the bowels. 
By the contractions of the muscular coat greatly excited, the 
intestine is not only diminished in diameter so as to resemble 
an earth-worm,f but in length also. This great contraction of 
the outer coats accumulates the vascular and villous coat as if 
into a heap ; which from the compression of the muscular coat 
is forced into the neighbouring relaxed portion. This first step 
leads only to a succession of actions ; for the fibres of the re- 
laxed or uncontracted part, sensible to the presence of this ac- 
cumulated and turgid villous coat, contracts in succession so 
* Huguenot gives an experiment illustrating the cause of ileus. He tied a 
ligature about the intestine of a cat, and found no antiperistaltic motion ex- 
cited. This is not wonderful ; it is the excitement arising from matter within 
the gut, to which there is no exit, and not the stricture of it, which is the cause 
of the violent symptoms. Many cases in the Museum will give the young 
student a correct judgment on this subject. 
Vide Scholium sub tit. Calculus insignis Ilii. Observ. F. Iliumi. Sandif. 
Thes. vol. iii. 
| See Haller’s Experiments, Opera Minora,- and “ Dissections of the Atro- 
phia Ablactatorumwith plates; by Dr. Cheyne. Sandifovt, vol. ii. p. 381. 
in Dysenteric.—Ibid. 244, 226 
OF THE SMALL INTESTINES. 
as to draw a part of the contracted gut within the relaxed 
portion. If the irritation is done away or ceases quickly, as 
in the experiments on animals, another turn of the intestine 
coming into play distends this, and undoes the intus-susceptio. 
But if the cause continues, the intus-susceptio is continued; 
the included part of the gut is farther forced into the other. 
By these means the vessels going to the included part are in- 
terrupted ; the villous coat swells more and more ; and several 
feet of the upper portion of the intestine is often in this way 
swallowed down. Is it not however in the natural course down- 
ward that this preternatural action always proceeds; for, as 
the excitement is violent and unlike the usual stimulus of food, 
and as we know that an unusual excitement is very apt to cause 
an inverted action, it often happens that the intus-susceptio 
is formed by the lower portion of the gut being included in 
the part above. 
VASCULAR COAT. 
This third coat of the intestines, is a stratum of cellular 
membrane in which the vessels of the gut are distributed. It 
might with equal propriety be called the cellular coat; and is 
indeed what some anatomists have called the third cellular 
coat. By inverting the gut and blowing strongly into it, the 
peritoneal coat cracks and allows the air to escape into this 
coat; which then swells out, demonstrating its structure to be 
completely cellular.* Its use evidently is to suffer the arteries, 
veins, and lymphatics to be distributed to such a degree of mi- 
nuteness as to prepare them for reflection into the last and in- 
nermost coat, and for entering into the structure of the villi: 
for they come to the extremity of the mesentery as considera- 
ble branches, but forming in this coat many branches, and 
these subdividing, their extreme branches are finally distri- 
buted to the inner coat. This is the coat in which, in some 
parts of the intestines, little glands or cryptae are lodged. 
VILLOUS COAT. 
The most curious part of the structure of the intestines is 
the villous or inner coat; for by its influence is the chyle sepa- 
rated from the general mass of matter in the bowels, and car- 
ried into the system of vessels. To this, all we have been de- 
scribing is merely subservient. 
The villous coat has a soft fleecy surface; and being of 
* An experimentto which Albinus attaches much importance. See also, in 
the Acad, de Bologna, a paper by Mr. D. G. Galeati on the fleshy coat of the 
stomach and intestines. OF THE SMALL INTESTINES. 
227 
greater extent than the other and more outward coats, it is 
thrown into circular plaits which hang into the intestine, taking 
a valvular form. They have the name of valvull c.onni- 
ventes. Some of them go quite round the inside of the in- 
testine ; others only in part. They are of larger or smaller 
extent in different parts of the canal: for example ; they 
begin a very little way from the lower orifice of the stomach 
irregularly, and tending to the longitudinal direction ; further 
down they become broader, more numerous, and nearly paral- 
lel ; they are of greater length, and more frequent in the lower 
part of the duodenum and upper part of the jejunum. These 
valvular projections have their edges quite loose and floating in 
the canal, and from this it is evident that they can have no 
valvular action. Their use is to increase the surface exposed 
to the aliment; to enlarge the absorbing surface ; and at the 
same time to give to it such an irregularity that the chyle may 
lodge in it and be detained. Into the structure of these plicae 
of the villous coat, the vascular or cellular coat enters, and 
generally in the duplicature a small arterial and venous trunk 
will be observed to run. That these plicae are formed chiefly 
by the laxity of the connection and the greater relative extent 
of the inner coat, is apparent upon inverting the gut, and in- 
sinuating a blowpipe under the villous coat, for then you may 
distend the cellular substance of the vascular coat so as entirely 
to do away the valvulas conniventes. 
The pile or lanuginous surface from which this coat has its 
name, is to be seen only by a very narrow inspection, or with 
the magnifying glass. It is owing to innumerable small fila- 
ments which project from the surface like hairs at first view, 
but of a flat or rounded figure as they are exhibited in a state of 
fulness and excitement or depletion. They consist (as appears 
by the microscope) of an artery and vein, and lacteal or ab- 
sorbing vessels, and to these we may surely add the extremity 
of the nerve. They have a cellular structure ; they are ex- 
quisitely sensible; and when stimulated by the presence of 
fluids in the intestines, are erected and absorb the chyle. They 
are the extremities of the lacteal absorbing system, and their 
structure would seem to be subservient to the absorption by 
the mouth of the lacteal vessel.* 
But the surface of this coat is not only an absorbing one, it 
also pours out a secretion; and, indeed, it is as a secreting surface 
upon which medicines can act, that it is to us one of the most 
powerful means of correcting the disordered state of the sys- 
* See further of their structure under the title of the Lacteal and Lymph- 
atic system, where the subject of absorption and the structure of the villi is 
treated. 228 
OF THE SMALL INTESTINES. 
tern. The fluid which is supplied by the surface of the intes- 
tines is called the liquor intericus; a watery and semi-pellucid 
fluid, resembling the gastric fluid. This fluid physiologists 
have affected to distinguish from the mucous secretion of the 
glands of the inner surface of the intestines ; but it is impos- 
sible to procure them separate.* 
GLANDS. 
Anatomists have observed small mucous glands seated in 
the cellular membrane of the intestines,! the ducts of which 
they describe as opening on the villous surface of the intes- 
tines. They are seen as little opaque spots when the intestine 
is cut in its length and held betwixt the eye and the light. 
They have been chiefly observed in the duodenum; few of 
them in the general tract of the small intestines. Little col- 
lections or agmina are observed, which increase in frequency 
toward the extremity of the ileon. It is natural to suppose 
that as the contents of the intestines become in their descent 
more acrid and stimulating, there will be a more copious 
secretion of mucus in the lower intestines for the defence of 
the villous coat. 
FUNCTION OF THE SMALL INTESTINES. 
In concluding the view of the small intestine, we cannot fail, 
I think, to express a correct idea of their function; the matter 
ejected from the stomach is a greyish, pultaceous turbid mass. 
In the small intestine we find that a precipitation or separation 
of feculent matter has taken place from the nutritious part. 
This nutritious matter called chyle is of a purer milky fluid, 
coagulable ; so that already that most remarkable character of 
the circulating blood is assumed by the digested matter. And 
what is still more curious, already do we see that consent 
established betwixt the containing and the contained fluids 
which is the source of all the actions of a living body. 
The chylous or nutritious matter from which the feculency 
is separated, is attracted by the surface of the villous coat of the 
intestine, and in an animal killed some time after taking food, 
* It has been supposed that the fluids excreted from the surface of the intes- 
tines were furnished by very minute foramina (which are visible by particular 
preparation) in the interstices of the villi. See the letter of Malpighi to the 
Itoyal Society of London on the pores of the stomach ; and the paper by M. 
Galeati in the Bologna transactions, on the Inner Coat, which he calls the Cri- 
briform Coat. These pores according to Galeati, are visible through the whole 
tract of the canal, and particularly in the great intestines. 
t Peyrus. BibJio. Manget. Brunnerus de glandulis duodeni. Morgagni 
Adversar. An. iii, viii. These he supposed additional pancreatic glands. OF THE SMALL INTESTINES. 
229 
the matter may be seen coagulated upon the inner surface of 
the intestine. 
Some are of opinion that the chylification is produced by the 
action of the bile, and that the effect of it is to precipitate the 
effete matter ; but I am more inclined to believe that it is the 
office of the part of the intestines we are now considering, to 
separate by attraction the chyle from the mass of ingesta: for 
supposing that we were to give the office to the bile, that would 
be a mere precipitation, and could not explain the attraction 
of the chyle to the villi.* 
It is more natural to suppose, that this very peculiar property 
of life, the coagulation, is bestowed through the influence of 
the villous surface of the intestine, than produced by the mere 
pouring in of a secretion like the bile. 
SECTION IV. 
OF THE GREAT INTESTINES. 
• 
The great intestines form that part of the intestinal canal 
which is betwixt the extremity of the ileon and the anus. 
They differ essentially from the small intestines in their size, 
form, and general character ; and in the texture, or at least in 
the thickness of their coats. 
The great intestine, beginning on the right side of the belly, 
rises before the kidney; passes across the upper part of the 
belly under the liver, and before or under the stomach.f Then 
making a sudden angle from under the stomach and spleen,£ 
it descends into the left iliac region. Here making a remarka- 
ble turn and convolution, it descends into the pelvis by a curve 
running in the hollow of the sacrum. 
The great intestines are accounted to bear a relation to the 
small intestines as five to twenty-five. 
The natural division of this portion of the intestine is into 
the ccectm, colon, and rectum.§ 
* In Mr. Cooper’s lectures in the College of Surgeons, this attachment of 
the chyle to the villi was considered as a discovery. But the statement will 
be found in former editions of this work. 
f This turn of the colon from the right across the belly is flexura prima, su- 
perior dextra hepatica. Soemmerring. 
t Flexura secunda, superior sinistra lienalis. 
§ Some authors divide the great intestine into six parts, enumerating the 
Caecum'; pars vermiformis: the right: the left; and the transverse colop; 
and the last part or rectum. 230 
OF THE GREAT INTESTINES. 
VALVULA COLI.* 
The extremity of the intestinum ileon enters, as it were, 
into the side of the great intestine at an angle.f And here 
there is a valvular apparatus formed by the inner membrane of 
the gut, which, more than any other circumstance, marks the 
distinction betwixt the small and great intestines; for as the 
effect of this valve is to prevent the regurgitation of the faeces 
into the small intestines, it marks sufficiently the nature of the 
change produced on the ingesta in their passage through the 
small intestine, and how unfit, in their changed and acrid state, 
they are to be longer allowed lodgment in the small intestines. 
Upon opening the caput coli, or lower part of the colon, oh 
the right side, and examining the opening of the ileon into it, 
we see a slit formed betwixt two soft tumid plicae of the inner 
membrane of the gut: the one of these is superior ; the other 
inferior. They are soft, and moveable, and seem scarcely cal- 
culated for a valvular action. But there is little doubt that when 
the great gut is distended or in action, they are calculated to 
resist the retrograde passage of the faeces into the ileon, though 
not absolutely to prevent it, as we know from what is vomited 
in the iliac passion4 In the form of the opening of the ileon, 
and in the broadness of the valvular membranes, there is con- 
siderable variety. The superior valve is transverse, smaller 
and narrower than the lower one; the lower one is longer, and 
takes a more extensive curve : and sometimes the lower one is 
so remarkably larger than the upper valve, that it gives a de- 
gree of obliquity to the insertion of the ileon into the colon, so 
as to approach to that structure which we see in the entrance 
* Valvula Coli or Valvula Banhini or Valvula Tulpii. 
| Of the opening of the small intestine into the greater, see Morgagni A<?.- 
versar. iii Animad. xi. 
t Morg. Mvei's. A. iii. An. ix. Kcrcknvgius Observ. xsxi OF THE GREAT INTESTINES. 
231 
of the biliary duct into the intestine, or the ureter into the 
bladder. At their extremities these valves coalesce and run 
into the common transverse folds of the colon: and this is 
what Morgagni has called the frsena or retinacula.* At this 
place of union of the ileon and colon the longitudinal muscu- 
lar fibres of the ileon are mingled and confounded with the 
circular fibres of the colon.f The circular muscular fibres 
certainly enter so far into the composition of the valve, that 
they embrace the margin, and by contracting during life, must 
make the experiments on the action of this valve in the dead 
body less decisive than they would be, were we certain that 
this valve acts on principles strictly mechanical. 
The discovery of the valve of the colon, and which, from its 
action in guarding the ileon, might rather be called the valve 
of the ileon, has been claimed or attributed to many anato- 
mists, chiefly to Varolius, Bauhin, and Tulpius ; and it some- 
times receives the name of the two latter anatomists. 
CCECUM. 
We have seen that the ileon is inserted into the side of the 
colon : now that portion of the gut which is below this union 
of the ileon is a round or slightly conical sac, from two to three 
inches in length. It is attached by cellular membrane to the 
iliacus internus muscle. It is not a regular sac, but is divided 
into large cells like those in the rest of the colon, and has 
some variety of form in different subjects. 
PROCESSUS, SUE APPENDIX VERMIFORMIS. 
There is appended to the coecum a small gut, also blind; 
but bearing no relation in size or in figure to any part of the 
intestinal canal. This gut,' from its smallness and twisted ap- 
pearance, like the writhing of an earth-worm, has received the 
name of vermiformis. It is somewhat wider at the connection 
with the great intestine, and stands off obliquely, so that some- 
times its inner membrane takes the form of a valve.:j: It 
scarcely ever is found containing faeces, but only a mucus ex- 
creted from its glands. In the foetus the appendix vermifor- 
mis is comparatively much larger, its base wider; upon the 
whole, more conical, and containing meconium ; and in the 
young child it often contains faeces. The coecum and appen- 
dix in the human subject are just sufficient, like the form of 
* Animad. xiii. f Winlow. 
4 Morgagni. M, Laur. Bonazzoli in the Acad, of Bologna. 232 
OF THE GREAT INTESTINES. 
the teeth, the stomach, and the intestines, generally to show 
that manholds an intermediate condition among the graminivo- 
rous and carnivorous animals. The coecum is one of the many 
means of retarding the descent of the food through the colon ; 
and it is found long and intricate in such animals as have a co- 
lon otherwise calculated to retain their contents. In carnivo- 
rous quadrupeds and birds the coeca are short; in the grami- 
nivorous quadrupeds and birds the coeca are long. 
GREAT DIVISIONS OF THE COLON. 
The great divisions of the colon are these : First, the right 
division of the colon rises from the insertion of the ileon, 
and from that part of the great intestine which is tied down by 
the peritoneum and cellular membrane, and ascends on the 
right side of the small intestines, until it gets under the mar- 
gin of the liver, and in contact with the gall-bladder. This 
part will be found to have some considerable variety in its 
form, as it is more or less distended. 
THE TRANSVERSE COLON.* 
The transverse colon is that part of the great intestine which 
takes a course across the belly, and which generally forms an 
arch before or immediately under the stomach. When this 
part of the colon however is much distended, being at the same 
time held down by the mesocolon, its angular turns reach 
under the umbilicus, nay even to the pelvis.f 
The left or descending colon is short: for from the 
place where the colon begins to bend down on the left side, 
to those violent turns which it takes before terminating in the 
rectum, it is but of small extent. Here it is attached to the 
diaphragm and psoas muscle. 
The sigmoid flexure of the colon:}: is formed by a nar- 
rowing and contraction, and closer adhesion of the gut to the 
loins below the left kidney, and to the cup of the ilium, by the 
peritoneum, which has the effect of throwing it into some sud- 
den convolutions. The colon then terminates in the rectum. 
PECULIARITIES IN THE COLON DISTINGUISHING IT FROM THE 
SMALL INTESTINES. 
The coats of the great intestines are the same in number 
* Coion transversum. Zona Colt. 
t For the varieties in the situation of this intestine and the viscera in gene- 
ral, see Morgagni Adversar. Annat ii. Animadver. ii. 
t From its resembling the Roman S. OF THE GREAT INTESTINES. 
233 
and in structure with those of the small intestines; but they 
are thinner and more difficult to be separated by dissection. 
The villi of the inner coat are smaller ; indeed betwixt the vil- 
lous coat of the ileon and the cfficum there is a distinction 
abruptly marked ;>X: the mucous glands or follicules are some- 
times very distinct; and, lastly, the muscular fibres have some 
peculiarities in their arrangement. The most characteristic 
distinction in the general appearance of the great and small 
intestines, is the notched and cellular appearance of the 
former. The cells of the colon being formed betwixt the 
ligamentous-like stripes which run in the length of the gut, 
have a regular threefold order. These cells give lodgment to 
the fseces; retain the matter ; and prevent its rapid descent 
or motion to the rectum. Here the fluids are still more ex- 
hausted, and the fseces take often the form of these cells. 
When the great intestines are torpid, and inert in their mo- 
tions, the fseces remain too long in the cells of the colon, and 
become hard balls or scybalse. But when in this state of 
costiveness the intestines are excited by medicine, not only 
is the peristaltic motion of the intestines increased, but the 
vessels pour out their secretions, loosening and dissolving the 
scybalse.f 
MUSCULAR COAT. 
The ligamentous-like bands of the colon form three fasci- 
culi running in the length of the gut: one of these, obscured by 
the adhesion of the omentum, is not seen without dissection; 
and the other is concealed by the mesocolon.:}: These bands 
are formed by the longitudinal fibres of the gut, being concen- 
trated into fasciculi, and not uniformly spread over the general 
surface, as in the small intestines: and being at the same time 
more firmly connected with the peritpneal coat, they give the 
appearance outwardly of ligament more than of muscular 
fibres.§ The inner or circular muscular fibres of the great in- 
testines are like those of the small intestines, uniformly spread 
over their surface, and are stronger than those of the latter. 
* Vide Albin. Annot. Acad. 1, vi. c. viii.de intestinis et tab. ii. f. vii. 
f See note ot‘ the pores of the intestines. 
i Stratum liberum, stratum omentale & tertium mesocolicum. 
§ See Morgagni. See also Galeati on the fleshy coat of the stomach and 
intestines, in the Memoirs of the Acad, of Bologna. 234 
Ob THE GREAT INTESTINES. 
RECTUM. 
The rectum* forms the last division of the great intes- 
tines; and I know no better proof of the impracticability ol 
altering the names in anatomy than this, that anatomists have, 
in almost every age, insisted on the impropriety of calling this 
gut, which answers in its shape to the curve of the sacrum, 
a straight gut; and yet always, and to the present day, it is 
rectum. 
From the last turns of the colon, called sigmoid, the gut is 
continued over the promontory of the last vertebra and sacrum 
(a little to the left side,) and falls into the pelvis. It runs 
down, in a curved direction, betwixt the sacrum and bladder 
of urine. In the upper part it is covered by the peritoneum, 
and has its fatty appendages like the colon, but less regular; 
and sometimes the fat merely deposited under the peritoneal 
coat. It is tied down by the peritoneum, in form of meso- 
rectum; but, deeper in the pelvis, it loses the peritoneum 
(which, as we have said, is reflected up upon the back of the 
bladder, and forms here lateral folds,) and the rectum is con- 
nected with the lower pai't of the bladder and vesiculae semi- 
nalis by cellular membrane. In women, the muscular fibres 
of the rectum and vagina are intimately connected.! 
The muscular coat of the rectum is particularly strong. The 
fleshy bands of the colon, spreading out, are continued down 
upon the rectum in an uniform sheath of external longitudinal 
fibres. The circular fibres of this part of the gut are also par- 
ticularly strong ; and towards the extremity, appearing in still 
stronger fasciculi, they obtain the name of sphincter, of which 
three are enumerated: and this, to distinguish it from the 
others, is called the intestinal or orbicular sphincter. 
The internal coat of the rectum does not deserve the name 
of villous, nor of papillaris. Its surface is smooth, and there 
are often distinctly seen little foramina like the mouths of 
ducts or follicules, in part the source of the mucous discharge, 
which is sometimes poured out from this gut. Towards the 
anus the folds become longitudinal, and terminate in the notch- 
ed-like irregularities of the margin.! 
* The name rectum is taken from the old anatomists who described from 
brutes. A Professor of Edinburgh calls it curvum, but this 1 cannot admit 
after reading JMorgagni Epist. Jhuit. xiv. 
f Winslow. 
± The presence of stricture within the anus seems to have given rise to 
conversation about a valve here. Morgagni Adversar. An. iii. Animad. vi. OF THE GREAT INTESTINES. 
235 
FUNCTION OF THE GREAT INTESTINES. 
One obvious use of the great intestines is to be a receptacle 
for the useless part of the food, that the matter descending 
through the small intestine may not as frequently be voided. 
In the next place we see, that in proportion as the quantity of 
the ingesta is great to the really nutritious part, the great intes- 
tines are capacious and long. Thus in the goat, the great in- 
testines are twenty feet nine inches in length, while in the lion 
they are three feet eight inches which is an increase ol 
length of intestine in the herbivorous animal more than in the 
carnivorous, by as much as the quantity of the useless part 
of the vegetable food is great in proportion to the animal 
food. 
Mr. Cooper, in his lectures to the College of Surgeons, gave 
the most diverting reason for the colon of sheep, and some 
other animals, being of a form calculated to retain the fasces, 
and form them into round dry pellets. It was to keep the wool 
and fur of their hips dry! Now these animals inhabiting lofty, 
dry, and sandy places, or extensive plains, they have this struc- 
ture of the great intestines to enable them to extract the whole 
moisture from the food, and consequently the less frequently 
to require drink. 
Professor Coleman has observed, that the water drank by a 
horse is very quickly conveyed through the canal, and depo- 
sited in the great intestines. 
It is matter of daily proof, that the aliment is deposited in 
the right colon liquid ; that in arriving in the rectum it is de- 
prived of fluid ; and that the lymphatics of the great intestine 
are found distended with a limpid fluid. 
From such views I have long entertained the opinion, that 
a very principal office of the great intestines was to imbibe 
the fluid from their contents in proportion to the wants of the 
system. 
But there is another office obviously performed by the intes- 
tinal canal: secretion, or rather excretion. The surface ol 
the intestine is the organ by which that matter (the waste in- 
cident to the changes of the economy,) which is not carried 
away in the urine, is thrown out of the system. 
The faeces contained in the great intestines, though offensive, 
are not putrid ; and the rapid change which takes place in the 
alimentary matter by chemical combination, when voided, 
implies that there is a controlling influence of the great intes- 
tine over its contents. Hence we may believe with some pa- 
thologists, that, in derangement of function ot the bowels, this 
'■ Sir Everard Home’s Lectures. 236 
OF THE LIVER. 
controlling influence being lost, such chemical change or putre- 
faction may take place in the contents of the colon, as to ren- 
der them a new source of morbid irritation. 
Not being satisfied with the observations I have met with on 
the different gases found in the intestinal canal, I may be ex- 
cused omitting to notice them in a book of anatomy. 
CHAP. III. 
OF THE SOLID OR GLANDULAR VISCERA OF THE ABDOMEN. 
The solid or glandular viscera of the abdomen are the 
liver, the spleen, the pancreas, the kidneys, the glandulas cap- 
sulares. 
SECTION I 
OF THE LIVER. 
Our attention is now naturally drawn to the liver, as it holds 
in so eminent a degree the sovereignty over the motions of 
the intestinal canal, and as it is so strictly connected with it by 
its system of vessels, and by its functions. The liver is the 
largest viscus in the body, and as in its size and proportion to 
the whole body it is great, so are its connections in other re- 
spects with the whole system very intimate. This is particu- 
larly evident in the diseases of the liver, and was the cause 
of the ancients ascribing to it so eminent ar place in the 
economy. 
In all ages authors have paid particular attention to the 
liver, and have exercised their ingenuity in giving various ex- 
planations of its function. The ancients made it the supreme 
director of the animal system. They supposed that they could 
trace the nutritious fluids of the intestines through the mese- 
raic veins into the porta and into the liver, and that it was 
there concocted into blood. From the liver to the right side 
of the heart they found the cava h<;patica, carrying this blood 
formed in the liver to the centre of the system : and through OF THE LIVER. 
237 
the veins they supposed the blood to be carried to the remote 
part of the body. 
The liver is the largest glandular body of the whole system. 
It must perform a very important function in the animal eco- 
nomy. But I confess there is a considerable obscurity in the 
subject. Let us in the mean time attend to the anatomy. 
Seat of the liver.—The liver is seated in the upper part 
of the abdomen, under the margin of the ribs, and towards the 
right side, or in the right hypochondrium. In the foetus it 
occupies more of the left side than it does in the adult. In- 
deed it is nearly equally balanced in the foetus, but the older 
the animal (at least during the first five years) the greater will 
be the proportion of it found in the right side. 
Without going into the more minute subdivisions of this 
viscus, we'may observe, that it is more uniform and smooth, and 
convex on the upper surface; on the lower, more irregularly 
concave. Its upper surface is applied in close contact to the 
concavity of the diaphragm, and in the foetus its margin is in 
contact with the abdominal muscles, because it falls lower than 
the margin of the ribs. Its lower and concave surface re- 
ceives the convexity of the stomach, duodenum, and colon. 
In a healthy adult subject the liver does not extend from un- 
der the margin of the ribs, unless near the pit of the stomach, 
but in the fetus and child it is much otherwise. In a fetus of 
the third and fourth month the liver almost fills the belly; it 
reaches to the navel, covers the stomach, and is in contact 
with the spleen. After the seventh month, other parts grow 
with a greater rapidity in proportion. Indeed some have 
affirmed, that the liver, or at least the left lobe, actually de- 
creases towards the time of birth.* But from this time to the 
advance to manhood the chest becomes deeper; the sternum 
is prolonged; and the diaphragm becomes more concave; so 
that the liver retires under the margin of the ribs, and its edge 
on the left side in the adult reaches no farther than to the oeso- 
phagus. When the liver becomes scirrhous and enlarged, its 
hard margin comes down so as to be felt through the abdomi- 
nal paries under the border of the chest. This enlargement 
of the liver, and consequent descent of its margin, is to be felt 
more easily by grasping the integuments of the belly, as if you 
expected to lift up the acute edge of the liver, than by pressing 
with the point of the finger. By this means we shall be 
sensible of the elasticity and softness below the liver, and of 
the resistance and firmness of the margin of it. The physi- 
cian, however, should not forget, that the depression of the 
* M. Portal, Acad, de Sciences, 1773, 238 
QE THE LIVER. 
diaphragm, and consequent protrusion of the liver by disease 
in the thorax, gives the feeling of an enlargement and harden- 
ing of the liver. The left great division of the liver is perhaps 
as often diseased and enlarged as the right, in which case it is 
more difficult to ascertain it by examination. 
Neither should a physician be ignorant, that by suppuration 
in the lungs, and consequent rising of the diaphragm, the liver 
is elevated considerably, so as to retire farther under the pro- 
tection of the false ribs. 
M. Portal, by running stilettos into the belly of the subject 
as it lay*upon the table, or was raised into the perpendicular 
posture, found that in the latter posture the liver shifted two 
inches. But it is almost superfluous to remark concerning 
these experiments, that they are by no means conclusive. In 
the dead body the abdominal muscles are relaxed; they yield 
to the weight of the viscera ; and the diaphragm is pulled 
down by the weight of the viscera. The margin of the liver 
necessarily falls lower, but in the living body there is a cloke 
and perfect bracing of every part by the abdominal muscles ; 
they do not yield, and very little if any alteration can take place 
in the situation of the viscera. 
It must be observed, however, that a considerable motion 
of the liver is a consequence of respiration, and of the action 
of the diaphragm. This motion is chiefly on the back part of 
the right lobe of the liver. The left lobe being more on the 
centre of the belly, and consequently opposite to the centre 
and less moveable part of the diaphragm, it is less affected b' 
the respiration than the larger right lobe. 
LIGAMENTS OF THE LIVER. 
The peritoneum is reflected in such a manner from the 
neighbouring parts upon the liver as to form membranes re- 
ceiving the name of ligaments. It has been explained, how- 
ever, that these are not the sole support of this viscus ; and 
that the compression of the surrounding abdominal muscles is 
the principal support of the liver, as it is of the other viscera. 
The broad ligament* of the liver is formed by two lamina 
of the peritoneum, connected by their cellular membrane, de- 
scending from the middle of the diaphragm and point of the 
sternum to the convex upper surface or dorsumf of the liver. 
This ligament is broadest where it passes down from the point 
of the sternum to the fossa umbilicalis ; but as it retreats back- 
* Ligamentum latum suspensorium, falciferme 
f See Plate I. of this volume. OF THE LIVER. 
239 
ward it becomes narrower, and is united to the coronary liga- 
ment near the passage of the vena cava. This circumstance 
with the curve which it naturally takes on the surface of the 
liver, gives it the shape of the falx. 
Ligamentum teres. The round ligament of the liver is 
the firmer ligamentous cord, which may be traced from the 
umbilicus along the peritoneum into the duplication of the 
broad ligament, and into the lossa umbilicalis. It is formed 
by the degenerated coats of the great vein which brings the 
florid blood from the placenta into the veins of the liver, and 
from thence into the right side of the heart of the foetus. 
The coronary ligament of the liver is formed in conse- 
quence of the attachment of the liver to the diaphragm. The 
attachment is of course surrounded by the inflection of the 
peritoneum from the diaphragm to the liver. It is called the 
coronary ligament, though it has been observed, that this 
attachment of the liver is not circular, but of an oval and 
very oblong shape. 
The lateral ligaments are formed by the peritoneum 
continued laterally. The right lateral ligament, like a mesen- 
tery, attaches the right and great lobe of the liver to the dia- 
phragm, and the left lateral ligament connects the left lobe 
with the diaphi'agm, and with the oesophagus and spleen. 
FORM AND DIVISIONS OF THE LIVER. 
The liver is convex and smooth on the upper surface ; con- 
cave and more irregular on the lower part; thick and massy 
behind and towards the right side; but anteriorly and toward 
the left side it is thin, and has an acute edge, so that it lies 
smooth over the distended stomach. 
Great right and left lobes of the'liver.—The first 
great division of the liver is marked on the convex surface by 
the broad ligament; which running back from the fossaurnbi- 
licalis divides it into the two great lobes, the right and left. 
When the concave surface of the liver is turned up, we see the 
same division into the right and left lobes by a fissure which 
runs backwards. 
It is on this lower surface of the liver that we have to mark 
the greater variety of divisions in this viscus. Farther, it is on 
the right lobe that those eminences are to be observed, which, 
with the indentations and sulci, give some intricacy to this 
subject. 
* See vol. ii.p. 173, and plate, p. 173, 240 
OF THE. LIVER 
Lobulus Spigelii.*—The lobulus Spigelii is betwixt the 
two greater lobes, but rather belonging to the right great lobe- 
From its situation deep behind, and from its having a particu- 
lar papilla-like projection, it is called lobulus posterior, or pa- 
pillatus. To the left side it has the fissure for the lodgment of 
the ductus venosus; on the right the fissure for the vena cava; 
and above, it has the great transverse fissure of the liver for 
the lodgment of the cylinder of the porta: obliquely to the 
right, and upwards, it has a connection with the lower concave 
surface of the great lobe by the processus caudatus, which 
Winslow calls one of the roots of the lobulus Spigelii. Its 
situation is within the circle or bosom of the lesser curve of 
the stomach. 
Lobulus caudatus.f—This really deserves the name of 
processus caudatus, for it is like a process of the liver, stretch- 
ing downward from the middle of the great right lobe to the 
lobulus Spigelii. It is behind the gall-bladder, and betwixt the 
fossa venae portarum and the fissure for the lodgment of the 
vena cava. 
Lobulus anonymus:(: is the anterior point of the great right 
lobe of the liver: or others define it to be that space of the 
great lobe betwixt the fossa for the umbilical vein and the 
gall-bladder, and extending forward from the fossa for the 
lodgment of the porta, to the anterior margin of the liver. 
Sometimes there is a projecting lobe on the margin of this 
part of the liver, and also there occurs a small projection on 
the left great lobe which acquires the name of lobulus lobi 
sinistri. 
Sulci, and depressions of the liver.—On the lower sur- 
face of die right lobe there may be observed two slight exca- 
vations, formed as it were by the pressure of the colon and ot 
the kidney. On the lower surface of the left lobe there may 
also be observed depressions answering to the convexities of 
the stomach and colon. But these are only the slighter irre- 
gularities which might pass unnoticed. There are, besides 
these, deep divisions which pass betwixt the lobes and lobuli, 
and indeed form these eminences. 
Umbilical fissure.§—From the anterior point of the two 
lobes there passes backwards to the left side of the lobulus 
Spigelii a deep fissure, which in.the foetus gives lodgment to 
the umbilical vein, and which in the adult receives the round 
ligament, where it is about to terminate in the left division of 
the vena portae. The back part of this fissure gives lodgment 
* Lobiiliisposterior—posticus—papellatus. j Processus caudatus 
Lobulus accessorius—anterioi'—quadraUis. 
>§ Horizontal fissure, fossa longitudinalis, longa, anterior. OF THE LIVER. 
241 
to the ductus venosus in the fcetus. This fissure divides the li- 
ver into its two right and left divisions, and upon the right side 
joins the transverse fissure. 
The transverse fissure is that which passes above thelo- 
bulus Spigelii and lobulus quadratus ; the processus caudatus, 
and the lobulus lobi sinistri. It is in this fissure that the great 
transverse division of the vena porta: lies. 
The posterior fissure* gives lodgment to the ductus ve- 
nosus. It is a division in the posterior margin of the liver be- 
twixt the left lobe and the lobulus Spigelii, and great lobe on 
the right. Sometimes, instead of the fissure or sulcus, there is 
a canal, as it were, in the substance of the liver. 
The fourth great fissure, is that for the lodgment of the vena 
cava. It sometimes is called, in contradistinction to the last, the 
right fissure, or the fissura vena cava;. It is a large deep 
division betwixt the lobulus Spigelii and the back part of the 
right lobe, for receiving the vena cava as it passes up upon the 
spine. 
The gall-bladder being sunk in the substance of the liver, 
the pit or excavation which receives it has been considered 
improperly as a fissure or fossa.f There likewise occur irre- 
gular fissures in the substance of the liver, which are like the 
cuts of the knife, and hold no regular place. 
OF THE VESSELS OF THE LIVER, AND OF THE CIRCULATION 
OF THE BLOOD THROUGH IT. 
There belong to the liver five distinct systems of vessels: 
these are, the vena portae; the arteria hepatica ; the venae ca- 
vse hepatic® ; the lymphatics ; and the biliary ducts.:}: These, 
with the nerves, form a very intricate system of vessels, but a 
lesson of the most particular importance to the physician. Be- 
fore speaking of the connections which these vessels constitute 
with particular parts, or with the entire system, we shall take 
a vie w of their origin and course. 
THE VENA PORTiE. 
This vein is divided into two parts ; that which belongs to 
the intestines, and which, ramifying on the mesentery, receives 
* Or sulcus ductus venosi, the left fissure, 
fit is generally called, fovea fe llis, or vallicula vesicul<e fell<ee. 
t And we might add, the arteries of the outer membrane of the liver which 
arise from the internal mammary, phrenic, epigastric, and even the spermatic 
arteries. 242 
OF THE LIVER. 
the blood of the mesenteric arteries ; and that part which 
branches in the liver, and distributes there the blood which it 
has received from the arteries of the membranous viscera. 
Even from this division, we see that the vena portae has a very- 
particular distribution ; that while it is collecting its branches 
from the spleen, stomach, and intestines, like the veins in the 
other parts of the body, into a trunk ; this trunk, instead of 
leading directly to the heart, or uniting with other veins in their 
course to the heart, enters the liver, and, like an artery, 
spreads into minute ramifications ; hence it is called the vena 
arteriosa. It resembles an artery in this also, that it has no 
valves like other veins. 
To be more particular; the vena portse takes its origin from 
the extreme branches of the coeliac, upper and lower mesen- 
teric arteries. The roots of the portse answering to these ar- 
teries are the splenic veins ; the gastro-epiploic vein which 
runs upon the great arch of the stomach ; the mesenteric vein 
returning from the small intestines ; and the right and middle 
colic veins, and internal hsemorrhoidal vein and left colic re- 
turning upon the mesocolon. These answering to the three 
great branches of the abdominal aorta, pass obliquely upward 
in three great divisions, and unite with some lesser veins, as 
the coronary and smaller veins of the stomach, and pancrea- 
tico-duodenalis. The trunk of the vena portse is now involved 
in the irregularly reticulated wreb of the hepatic vessels, arte- 
ries, veins, glands, lymphatics, nerves, and biliary ducts, with 
their cellular membrane. It passes upward somewhat obliquely 
to the right; and enters the porta* or the sinus betwixt the 
processus caudatus and lobulus Spigelii. 
When the vena portse has entered the liver it divides into 
two great branches, which running directly transverse, and 
being of large capacity, are sometimes called the cylinder of 
the vena portse. Of these two great branches of the vena portae 
within the liver, the right is greater in diameter, but shorter :f 
it ramifies in the great right lobe of the liver. The left is 
longer considerably, and filling the tranverse fissure it is re- 
flected up into the umbilical or horizontal fissure, and is given 
to the left lobe, to the upper and more anterior part of the 
right lobe, viz. lobulus anonymus, and to the lobulus Spigelii. 
The minute ramifications of the vena portae every where 
pervade the substance of the liver, and inosculate with the 
veins of the surface belonging to the peritoneal coat. The 
* Sometimes it has been found divided before entering the liver. It has 
been also found to divide into three branches, in which cases, says Haller, two 
go to the left side. 
t Into this branch sometimes the vein of the gall-bladder enters. OF THE LIVER. 
243 
blood of the vena portae is received into the extremities of the 
venae cavae hepaticae. 
ARTERIA HEPATICA. 
For the course of this artery from the root of the cceliac 
artery, to its entrance into the liver, see the description of the 
arterial system. The arteria hepatica and the venae portae are 
supported by the same sheath, the lesser vessel encircling the 
greater, like a tendril. While they have distinct functions, 
both terminate in the same returning veins : that’ is to say, 
whether we admit that one or both open into the biliary ducts, 
yet they have the same relation to the venae cavae hepaticae 
which the arteries of the other parts of the body have to their 
returning veins. 
VENvE CAViE HEPATIC^. 
We have seen, that the right auricle of the heart is close to 
the diaphragm above, and that the liver adheres to the lower 
surface of the diaphragm. We have also found that there was 
a groove in the back part of the liver for the transmission of 
the vena cava abclominalis. Now as the vena cava ascending 
from the lower parts of the body to the heart is perforating 
the diaphragm,, it is joined by two large veins from the liver, 
which, from their size and form, being the returning veins of 
the liver, are termed in general the vena? cavaj hepaticae. 
These veins sometimes pierce the diaphragm together with 
the cava abdominalis, so that there is to be observed one large 
perforation in the diaphragm ; but generally they pass the 
diaphragm close to the great vein, but so that there are three 
openings in the diaphragm. When these hepatic veins are 
traced into the substance of the liver, they are seen to be 
gathered together from all parts of the liver in two, or some- 
times three great branches.. 
The communication betwixt the vena portae and the venae 
cavae hepaticae are so free, that several anatomists have ima- 
gined a peculiar and more immediate communication of their 
branches than holds in other parts ol the body betwixt the 
arteries and veins; a circumstance which appeared to them 
the more necessary, considering the lesser impetus with which 
the blood flows in the vena portae than in the arterial system. 244 
of the liver. 
Gall-Bladder and Duct. 
BILIAKY DUCTS* 
The smallest subdivision of the substance of the liver is 
called acinus, and that molicule is supplied with a branch of 
the venae portae, arteria hepatica, and venae hepaticae. With 
these there is also seen a minute ramification of the excretory- 
duct of the liver. These last minute branches are the roots of 
the biliary duct; for they, running into each other, form trunks 
resembling the branches of veins, and these attaching them- 
selves to the vena portae form the greater trunks, answering to 
the right ahd left side of the liver. These two branches of 
the hepatic duct approaching each other, unite (C,) where 
they are attached to the right branch of the vena portae. 
Their union constitutes the hepatic duct or ductus chole- 
dochus. 
When the duct of the liver has advanced a little way from 
the transverse fissure, it is joined by the cystic duct (B,) or 
perhaps we should rather say, considering the use of the cys- 
tic duct, that it is reflected from the hepatic at an acute angle 
to the right side. The ductus cysticus is much smaller than 
the hepatic duct, and is somewhat curved near the gall-blad- 
der: it takes a very sudden turn downward, as is seen in the 
marginal plate. 
The hepatic duct,-after being joined by the cystic duct, con- 
* Explanation of the plate of the gall-bladder. 
A The gall-bladder. 
B The cystic duct. 
C The hepatic duct. 
I) The common duct. 
E The hepatic artery. 
F the cystic artery coming off from it OF THE LIVER. 
245 
tinues its course under the name of ductus communis chole- 
dochus, or common duct.* Now become somewhat larger, it 
takes its course under the head of the pancreas to the back 
part of the duodenum, about five inches from the pylorus. 
Before it enters the gut, or more generally while included in 
the coats, it is joined by the pancreatic duct. Having pierced 
the muscular coat, it runs for some time in the cellular coat, 
in the length of the gut, and then opens upon the eminence of 
a considerable valvular plica of the inner coat. 
This hole is regularly limited, and by no means equal to the 
diameter of the duct, either where it is contained within the 
coats of the gut, or in its course from the liver to the gut. 
Sometimes the hepatic and pancreatic duct open by distinct 
perforations. 
The outer coat of these ducts is smooth and strong,! within 
this a cellular and nervous coat is described,! and muscular 
fibres imagined ; but the inner coat is worthy of attention. It 
is reticulated in such a way, that a probe pushed up the duct 
is caught by their valve-like action. 
We have already noticed, that the gall-bladder is attached 
to the lower surface of the right lobe of the liver, and parti) 
buried in its sinus : it has sometimes occurred that it was 
merely suspended to the liver by a membranelike a mesentery. 
It is a bag of a pyriform shape ; its greater end or fundus is 
contiguous to the colon; its lower end or neck to the duode- 
num.§ It is generally of a size to contain an ounce, or an 
ounce and a half, of bile. 
The coats of the gall-bladder are the outer peritoneal coat; 
a middle cellular coat, what from its analogy to that of the in- 
testines we should call vascular coat; and an inner coat. In 
the intermediate coat muscular fibres have been looked for 
with great eagerness, but none have been demonstrated, al- 
though a conviction remains that there are muscular fibres in 
the composition of the coats of the gall-bladder. This coat 
gives form, limit, and strength to the gall-bladder. The third 
GALL-BLADDER. 
* Ductus clioledochus, hepatico-cysticus, (D.) 
f Although this coat resists in a considerable degree the distention of the 
duct, when blown into or injected, yet the whole are sometimes so distended 
as to admit the thumb. But this is rather to be considered as growth and 
enlargement, than distention. 
i By Haller. 
§ The gall-bladder has been observed wanting; in which case the dilated 
ducts would seem to have been capable of retaining a quantity of bile ready 
to be evacuated into the intestine. A double gall-bladder has sometimes been 
found. 246 
OF THE LIVER. 
or inner coat is formed into innumerable rugae, so as to take a 
cellular or reticulated texture. These loculi, as we may call 
them, thus formed by the duplicature of the internal membrane, 
are of considerable variety in shape, square, round, or triangu- 
lar. These rugae, and the whole internal membrane of the 
gall-bladder, have a beautiful and minute net-work of vessels 
upon them; and in these cells there can be little doubt that 
there are small mucous follicules or pores, or that an exudation 
from extreme vessels, sheaths the surface from the irritation 
of the acrid bile. The extreme degree of vascularity and re- 
ticulated texture of this inner coat of the gall-bladder is not 
apparent before the sixth or seventh month of the foetus, and 
then it takes a peculiar texture in preparation for the recep- 
tion of the secreted bile. 
Towards the opening of the bladder into the cystic duct 
the rugae assume a semilunar figure, and seem to have a val- 
vular action, in at least so far that they seem intended to give 
a degree of difficulty to the passage of the bile. The same 
structure of the internal coat prevails in the cystic duct. 
However strange it may appear to one, considering the re- 
lation of the liver as a gland to its ducts, and to the gall-blad- 
der as a receptacle of the bile, an opinion was entertained that 
the bile of the gall-bladder was secreted by its own coats, and 
that it was of a different nature from the bile conveyed from 
the substance of the liver. Without further argument it is 
sufficient to say, that when the cystic duct is tied, or when it 
is preternaturally obstructed, there is no bile secreted into 
the gall-bladder. 
From the connections of the gall-bladder, and from the con- 
siderations of the whole anatomy, there can remain no doubt 
that the gall-bladder is a mere receptacle, reserving a sufficient 
store of this fluid for the due change to be performed upon the 
food: that as the stomach is not at all times loaded with food, 
nor the chyme and fluid from the stomach incessantly passing- 
through the duodenum, neither is the bile at all times running 
from the gall-ducts. On the contrary, as the stomach is emp- 
tied of its contents at stated intervals, the gall-bladder affords a 
provision for a quantity of bile to be evacuated proportioned to 
the food, which is passing the duodenum. Whether we should 
conceive that this is a necessary consequence of the retention 
of the bile in the gall-bladder, or a wise provision of nature, I 
am uncertain ; but it appears, that the longer the bile is re- 
tained, or the longer the fast and the deficiency of food in the 
duodenum, the more acrid and inspissated is the bile, and the 
greater also in quantity. This inspissation of the bile takes 
place in consequence of the activity of the lymphatics, which 
ramifying on the coats absorb the thinner part of the bile. 247 
The rugae of the inner coat of the gall-bladder may be a 
provision for extending the surface either for absorption or se- 
cretion ; but I rather imagine that they are merely a provision 
for permitting extension more freely. 
The gall-bladder is supposed by some to be emptied by the 
general pressure of the abdomen; an opinion founded on a 
mistake, which a very little consideration might correct. Others 
think that the stomach, or duodenum, or colon, being distended 
by the food, compress and empty the gall-bladder; while others 
with more apparent correctness allege, that it is emptied in con- 
sequence of a consent of parts. With the latter I would confi- 
dently affirm, that as the aliment passes the duodenum, the bile 
follows apace, either from the alternate contraction and re- 
laxation of the duodenum occasioning a relaxation of the ori- 
fice of the ducts, or more probably from the ducts being ex- 
cited, as the salivary glands are excited by the presence of 
sapid bodies in the mouth. By want and hunger, on the con,- 
trary, the gall-bladder is allowed to be distended: there is no 
call for its evacuation. 
Experiments would even teach us, that the gall-bladder has 
not the same irritability excitable by stimuli applied to the 
coats, which the stomach, intestines, or bladder of urine have ; 
which is a proof that, like the iris, and many other parts of the 
body, its action is roused more powerfully by the indirect sti- 
mulus and through consent of remote parts, than by the dis- 
tention of its coats ; whereas the intestines and bladder have 
it in their constitution to be excited to contraction by simple 
distention. 
From experiments it would appear, in confirmation of what 
is here alleged, that while the food is in the stomach, little 
bile is discharged ; but that it flows when the matter is passing 
the duodenum, so that a great quantity is then found in the gut. 
On the contrary, in a state of want and hunger, the gall-blad- 
der is greatly distended, and yet little bile flows from it; al- 
though it is not only more accumulated, but more acrid and 
bitter.* 
That the gall-bladder is not destitute of irritability and the 
power of contraction, would appear from many cases, where, 
like the urinary bladder, it contracts upon concretions, and 
becomes thick in its coats. 
The retention of the bile, surcharging the ducts, and dis- 
tending the gall-bladder, and the sudden discharge of accumu- 
lated bile, and the irregularities of its course when influenced 
OF THE LIVER. 
* Anat, generate de Xav, Bichat, tom, iv. p. 6, 248 
OF THE LIVER. 
by disorder of the viscera, are the source of the most severe 
and distressing symptoms.* 
In the dead body we see the colon and duodenum, or what- 
ever parts lie in contact with the gall-bladder, stained with 
bile ; but this evidence of transudation which is found in the 
dead body, is not seen in the living, while the stain from the 
bile is observed to be deeper and more extensive in bodies long 
dead. It is therefore another example of the peculiar proper- 
ties inherent in the living fibres, that no transudation is allow- 
ed ;f but that the fluids, which appear as if exuding from the 
living surfaces, are really discharged from organic pores, or 
from the extremities of vessels. 
The liver is firmer and drier in some degree than any of the 
other viscera; the intertexture of membrane is weak, and 
in consequence the substance of the liver is friable and easily 
torn. When cut or torn, it seems for the greater part vascular : 
or it displays the mouths of innumerable ducts and vessels, 
and, after a minute injection, the blood-vessels seem to per- 
vade every particle, even when examined with the microscope. 
This texture of vessels, in which we may say the substance 
of the liver chiefly consists, is surrounded with a delicate mem- 
brane, the continued peritoneum. It retains the character of 
peritoneum, in being a simple membrane, whitish, and a little 
pellucid. In this membrane minute arteries and veins ramify, 
which are unconnected with the internal system of the vessels, 
and in the close cellular membrane beneath it the lymphatic 
vessels take their course. 
When a section is made of the liver, the vessels may be 
thus distinguished: the ducts by the thickness of their coats, 
and their yellow colour; the arteries by a less degree of thick- 
ness, and a more resisting elasticity ; the branches of the vena 
OF THE MINUTE STRUCTURE OF THE LIVER 
* We have example of this in a Treatise on the Diseases of the Bowels of 
Children, by Dr. Cheyne. 
f The peculiar odour of the intestines of a dead body is not perceptible in 
the living; when in dissection the fingers touch the intestines,they retain the 
odour long: but on handling the intestine in the operation for hernia, the bad 
smell does not attach, nor is it at all perceptible. Poison in the stomach of an 
animal will pervade the coats and afi'ect the whole substance, if permitted to 
remain after death: but if the stomach containing the berries of the laurus 
cer. be taken from the pheasant of America, they are wholesome food. The 
peccary, or Mexican hog, when killed, must have the dorsal gland immediately 
cut out, or the disagreeable smell of this secretion makes the flesh unfit to, be 
eaten. For the same reason the Indians cut away the noxious glands from the 
skunk immediately when killed. All these examples show that the living 
substance resists the contamination, but that when the parts are dead they no 
longer resist the percolation of the fluid, the colouring or odorous matter. 
For much of the anatomy of the liver, and of the bile, see Morgagni Ad- 
versar. An. hi. A. xx, to xxyii. OF THE LIVER. 
249 
portae and the cava hepaticae by the thinness of their coats, of 
•which those of the latter are considerably the weaker. 
With the investiture of the peritoneal coat of the liver even 
the vascular tissue of the body of the liver has no communica- 
tion by vessels.* It is therefore considered as a peculiarly dis- 
tinct organization. By the proofs from anatomical injections 
we are informed, that there is a free intercourse through the 
extreme branches of all the five systems of vessels in the liver. 
By making minute injections, and sections of the liver, there 
seems no likelihood of gaining information of the structure and 
connections of these vessels. Walther, who seems to have ex- 
amined more methodically and minutely than any other anato- 
mist in any age, could make no distinction of parts. In what- 
ever way he made his sections, whatever system of vessels he 
filled, whether the whole vessels or each separately, he could 
not ascertain the direction and course of any particular vessel, ‘ 
nor its inosculations, but all was obscure, and as if constituting 
one chaotic mass. In wet preparations, however, he observed, 
that the extreme branches of the hepatic artery opened into 
the vena portae: that the branches of the vena portae had a 
double termination : that some of them, by a sudden turn and 
serpentine course, terminated in the branches of the vense 
cavse hepaticae ;f while others were seen to terminate or open 
into the biliary ducts. Further he observed, that in all the 
branches of the vena portae there was a peculiar compressed 
appearance which distinguished them from all the other ves- 
sels of the viscus. 
There have been observed intersections of the intimate mem- 
brane of the liver, which divides and subdivides the fasciculi 
of vessels. These are, however, somewhat obscure and indis- 
tinct. The last perceptible subdivisions of the substance of the 
liver have been called acini:): ; and they are rather presumed 
than directly proved to have in their composition an extreme 
ramification ol the several vessels of which the liver consists.§ 
We have seen that Malpighi conceived that these bodies 
were simple glands collected on the ramifications of the ves- 
sels ; that they were little vesicles ; and that from them the 
pori biliarii took their origin. In this opinion he was success- 
fully opposed by Ruysch, who affirmed that they were vascu- 
* Soemmerring. Wa!ther,loc. cit. See. 
f T should imagine that in this he might have been deceived by the lesser 
branches of the porta: (filled with injection) opening into the side of the larger 
trunks; and that there is no such termination of the hepatic arteries in the 
sides of the vena portarum, so that their open mouths are discernible. 
+ See the definition in the introduction to the anatomy of the viscera. 
§ Acinos nemo rejic'it, ne Ruyscliius quidem, sed de interior fabrica dispu- 
tatur. Haller. 250 
OF TIIE LIVER. 
lar ; and in this opinion he has been supported by Albinus. It 
"would in truth appear, that the description of these partitions 
of the substance of the liver, and the ultimate subdivision of 
it into these little grains, about which there has been so much 
controversy, is not founded in an accurate observation, and 
that there are neither cryptae, hollow and cellular, nor little 
bodies made up of convoluted arteries, but the minute parcels 
of vessels, which are collected together and united by fine 
cellular texture; they may be called acini, according to the 
definition which has been given in the introduction.* 
OF THE FUNCTION OF THE LIVER, AND OF THE SECRETION 
OF THE BILE. 
Notwithstanding that the circumstance of the biliary duct 
being discovered points to one very obvious use of the liver, 
yet I am not satisfied that our knowledge of its functions is 
nearly perfect. In animal bodies one organ ministers to 
several functions. As the tongue is the organ of taste, of 
speech, of deglutition; as the lungs minister to respiration, to 
circulation, to speech, to smelling; as the skin serves many 
purposes, so I believe that we are too easily satisfied with 
discovering one use of the liver in secreting the bile and 
stimulating the intestines. 
The great size of this gland would impose upon us the belief 
that it serves some very important use in the animal economy, 
and the state of the system which originates with the disorder 
of the biliary secretion strengthens that belief. The function 
which it performs is probably the separation of some form of 
useless carbon ; as M. Fourcroy has taught, that the bile is 
formed in a great measure of the combustible matter of the 
blood, thus making the liver a true auxiliary of the lungs. 
Upon reviewing the whole system of the liver the peculiari- 
ties in the vena portae strike us the most. It occurs to us 
that this great supply of blood to the liver, with the slow mo- 
tion peculiar to venous blood, after having gone the circulation 
through the intestines, is a provision for the discharge of car- 
* Finally, Ruysch’s opinion may be given in these words: (Epist. ad Virum 
Clar. Ner. Boerhaave, p. 69.) “ Sed nolo diutrus tergiversari, fateor ergo, 
quod, quando primo incipiebam me exercere in anatomicis, videbam tunc 
quidem, quod in jecore humano se ostendebant acinuli parvi innumerabili nu- 
mero, qu<e turn temporis appellabantur glandulx; nam nemo cogitabat aliter 
sed manet sola jam haec questio, an acinuli hi hie herentes sint glandul* sim- 
plicissimac, foliculi cavi cum emissario an quid aliquid ? dico nemo demonstra- 
vit illos tales esse ut hie assumis. Imo vero facile jam erit demonstrare,acinos 
hos cum criptis antea pertractis nihil commune habere : quia oculis nostris 
non apparent ut membranulse cavse & quia etiam non habent emissarium. Sed 
componuntur tantum ex extremitatibus ultimis vasculorum sanguiferorum 
unitis in formam spherze rotunditatis, neque, quantum possum vidcre etiam 
membramila aliqua sua singulari circumambiuntur.M OF THE LIVER. 
251 
bon and for the secretion of the bile. It is believed, that the 
secretion of bile is made from the blood of the vena portae. 
But as we see that this blood distributed by the branches 
of the vena portae in the liver must be so far exhausted as to 
become incapable of all the uses accomplished by the arterial 
blood in other glands, that although the vena portae be pecu- 
liarly adapted to secrete the bile, it is not capable of supplying 
the nutrition and the energy to the substance and vessels of the 
liver, there is a necessity for arterial blood being sent to this 
gland through a branch of the arterial system. We have had 
occasion to remark, that no part retains its functions in vigour, 
nor the living properties which are inherent in it, while the 
whole economy is entire and correct, unless the arterial blood 
be circulated through it. Therefore it would appear neces- 
sary that the arteria hepatica, a branch of the aortic system, 
should also be bestowed upon this viscus. These arteries per- 
form the same office here in the liver that the bronchial arte- 
ries do in the lungs, or the coronary arteries in the heart, or 
the vasa vasorum in the great vessels. The pulmonic artery 
carries venous blood into the lungs, which having returned 
from the circulation of the body, cannot send off smaller 
branches to supply the membranes and vessels of the lungs ; it 
is necessary that for this purpose branches of the aortic sys- 
tem shall enter the lungs. Again, in the heart the blood con- 
tained in its ventricles is incapable of supplying its substance; 
or the blood coming through the canals of the great vessels 
cannot be the means of ministering to the active powers of 
their coats : but for this purpose the vasa vasorurp are distri- 
buted through the coats of the vessels. These vessels there- 
fore bear an analogy to the arteria hepatica in the liver. 
We must not however suppose that this scheme of the ac- 
tion of the vascular system of the liver, however rational and 
simple, will be universally allowed. Indeed there are circum- 
stances which seem to stand in opposition to it. Of these, 
the most interesting is the case of unusual distribution of the 
vessels of the liver communicated by Mr. Abernethy. 
The subject was a female infant which was supposed to be 
about ten months old. Among other varieties it was observed, 
that the branch of the cceliac artery distributed to the liver was 
larger than common, and exceeded by more than one third 
the usual size of the splenic artery. This was the only vessel 
which supplied the liver with blood for the purpose of either 
nutrition or secretion. The vena portarum was formed in the 
usual manner, but terminated in the inferior cava nearly on a 
line with the renal veins. The liver was of the usual size, but 
had not the usual inclination to the right side of the bodv: it 252 
OF THE LIVER. 
was situated in the middle of the upper part of the abdomen, 
and nearly an equal portion of the gland extended into either 
liypochondrium. The gall-bladder lay collapsed in its usual 
situation. It was of a natural structure, but rather smaller than 
common. On opening it there was found in it about half a 
tea-spoonful of bile. The bile in colour resembled that oi 
children, being of a deep yellow brown, and tasted like bile, 
but it was not so acridly bitter and nauseating as common bile . 
Mr. Abernethy remarks upon this case, that when an anato- 
mist contemplates the performance of biliary secretion by a 
vein, a circumstance so contrary to the general economy of 
the bod}’, he naturally concludes that bile cannot be prepared 
unless from venal blood ; and he also infers, that the equal 
and undisturbed current of blood in the veins is favourable 
to the secretion ; but that the circumstances of this case, in 
which bile was secreted by an artery, prove the fallacy of this 
reasoning.* 
We may further observe on this case, that it does not 
prove the bile to be the natural economy, secreted by the ar- 
teries and not even by the vena porta?; for the artery here 
was unusually large, so that it perfonned a function in this 
instance which it does not usually perform. On the contrary, 
had the artery been of the usual size, we might then have con- 
cluded that the vena portae was distributed to the liver to serve 
some lesser use in the economy of the system, and that it did 
not secrete the bile. 
The liver, it is said, was of the ordinary size. Now as the 
bulk of the liver is, in its natural state, made up of the di- 
lated veins, it is some proof of -what I should imagine had 
taken place here, that by some provision of the vessels the 
arterial blood had been diffused, and the celerity of its mo- 
tion checked previous to its ultimate distribution. Nay, it may 
have opened into the branches of veins answering to the ex- 
tremities of the vena porta?. 
In the deficiency of the acrid and bitter state of the bile, 
there is in this case evidence that the bile formed from the 
arterial blood is unlike the perfect secretion. I conceive thi: 
opinion to be countenanced by the peculiar circulation of the 
blood in the liver of the feetus, and by its effects upon the se- 
cretion. We have seen in the foetus, that almost the entire 
gland is supplied with arterial blood returning from the um- 
bilical vein; and the natural deduction from this is, that this 
is the cause why the bile in the foetus is of a less stimulating 
quality, and smaller in quantity than in the adult. 
* SeeMr. Abernethy’s case of uncommon formation of the liver. Phys. Trans • 
actions. OF THE LIVER. 
253 
1 conclude, that this singular and interesting case may 
strengthen the opinion which some have entertained, that the 
extreme branches of the hepatic artery pour blood into the 
extremities of the vena portae previous to this formation of the 
bile by these veins ; but it still leaves us with the general con- 
clusion, that the peculiarities in the distribution of the vena 
portae are a provision for the secretion of the bile, and that the 
branch of the aortic system, the hepatic artery, is otherwise 
necessary to the support of the function of the liver. 
Finally, as to the use of the liver independently of the se- 
cretion of the bile, we must lay aside the opinions mentioned 
by Haller, that it supports the diaphragm, pushes it up in ex- 
piration, and receives the contraction of it equally in inspira- 
tion, so as uniformly to compress the other abdominal viscera ; 
or that it foments and cherishes the stomach by the heat of 
its blood. These are at least as bad as the theories of the an- 
cients mentioned in the beginning of this section. Haller 
sometimes puzzles us by the promiscuous admission of all 
facts and every kind of theory, with something of indecision 
in giving his own opinion. 
There is another remark of Haller which deserves attention. 
When I reflect, says he, that there is no bile requii'ed in the foe- 
tus, there being no food received : when again I see that the 
liver is of great size in the foetus, and not small like the lungs, 
which are destined to an operation in the economy after birth, 
I cannot but suspect that it has some other use in the foetus 
than the secretion of the bile. ;If the umbilical vein had 
opened directly into the cava, he thinks it would have returned 
with too great an impetus upon the heart, and would by its 
preponderancy have retarded the return of the blood from the 
lower extremities. He thinks that the liver is useful in break- 
ing and weakening the impulse of the blood from the umbili- 
cal vein; that it is a guard to the right auricle, which would be 
otherwise endangered by the rapid flow of the blood. Now 
surely the liver is much less able to stand the impulse of the 
blood than the heart; and yet there is no provision for the 
breaking of the force of the blood in the liver. Further, there 
is a direct duct of communication leading to the heart. There 
is no reason to believe that the umbilical vein carries back the 
blood with greater force than any other returning vein : on the 
contrary, from its size and the length of its course it is natural 
to suppose the motion of the blood in it to be very slow and 
equable. 
We must look upon the peculiarities in the circulation of the 
blood in the liver of the foetus as a provision against the se- 
cretion. of stimulating bile ; for when the child is born and the 254 
OF THE LIVER. 
circulation altered, bile is formed more abundantly, and be- 
comes the stimulus to the whole abdominal viscera, rousing 
them to new action. As to the comparison which Haller has 
made between the state of the liver and that of the lungs, it 
is evident that the latter, though small in bulk, are fully formed, 
and want only inflation to complete their function. In the- 
liver of the foetus the vessels are distended with blood, to give 
them the size requisite for this future function; but that blood, 
either from its qualities or from the easy and direct passage it 
has into the heart, doesnot secrete the bile of a quality to stimu- 
late the ducts and intestines, as in the adult circulation. If it 
did, we should not see the alimentary canal of the foetus load- 
ed with green matter, and in a state of inactivity and torpor. 
The natural bile of the adult system is of a deep yellow 
colour ; when concentrated by the absorption of its liquid parts, 
it is brown; sometimes the bile of the gall-bladder is green, 
although there has been no disease in the liver to compare it 
with something familiar: the bile is of the colour of wetted 
rhubarb. As to the use of the bile, the more common opinion 
is that it precipitates the feculent matter from the chylous 
fluid. But for this there is no other foundation than that such 
a separation does actually take place; but we have bestowed 
that action on the villous coat of the intestine,—with what 
show of reason may be seen above. 
Mr. Hunter was of opinion that this bile did not incorpo- 
rate with the chyle ; it certainly does not confer on that fluid 
its sensible qualities, though it may be possible, according to 
the opinion of M. Fourcroy, that the alkaline and saline in- 
gredients of the bile may combine with the chyle, while the 
albumen and resin may combine with the excrementitious 
matter. 
If the bile was a mere excretion, if it were poured into the 
intestines merely to be thrown off, then the duct would have 
entered into the lower part of the gut, and not into the duo- 
denum. 
Neither would we have observed that connection betwixt 
the state of digestion and the discharge of the bile into the in- 
testine, which I have already noticed. 
Perhaps we may conclude, that the liver linked in close 
sympathy with the intestines, connected by nerves, by blood- 
vessels, and by ducts, holds a control over their action by the 
stimulating fluids which it supplies to them. 255 
OF THE PANCREAS, 
SECTION II. 
OF THE PANCREAS. 
The pancreas is a gland the largest of those which have 
been called the conglomerated, that is, distinctly consisting of 
lesser parts united. It is of a long form like a dog’s tongue, 
and lies across the spine, and behind the stomach. Its excre- 
tory duct opens into the duodenum. 
The pancreas is confined betwixt the two lamina of the 
mesocolon, and it is united to them by a loose cellular mem- 
brane; it lies before the great mesenteric vessels, with its pos- 
terior face upon the spine and aorta, and covered anteriorly 
by the superior lamina of the mesocolon. It is divided into 
the head, body, and extremity. The head is towards the right 
side: its small extremity touches the spleen, and is near the 
capsule of the left kidney: but towards the right extremity it 
increases gradually in massiness, until its head lodges upon the 
duodenum. It is like the salivary glands in its appearance, 
consisting of lobules successively smaller and smaller ; and it 
also resembles them in the manner in which its duct is formed. 
The duct* begins towards the left extremity by exceedingly 
small branches: these running together form a middle duct, 
which taking a serpentine course towards the great extremity, 
and increased by the accession of the lateral branches in its 
course, becomes nearly of the size of a writing quill. Towards 
the right, the head of the pancreas is irregular, and indeed a 
lesser pancreas generally projects from it. Approaching the 
duodenum the duct unites to the biliary duct, and opens along 
with it into the duodenum. A valve has been described as in 
the extremity of the pancreatic duct, but it is certainly inca- 
pable of the action of a valve, as the bile has been found to 
have gone retrograde into the trunk of the pancreatic duct. 
Sometimes there are two pancreatic ducts, but more frequently 
the part of the gland next the duodenum, and which is called 
the round head of the pancreas, has an excretory duct pecu- 
liar to itself, which either opens into the duodenum separately 
from the main duct, by piercing the coats of the intestines 
nearer the stomach, or sometimes opens further down. In 
* Ductus Virsungi. 256 
OF THE PANCREAS. 
the clog there are distinctly two ducts, the one opening into 
the biliary duct, the other separately into the duodenum. 
De Graff, Ruysch, and many others, have made experi- 
ments to discover the nature of the secretion from the pan- 
creas. Tubes were introduced into the ducts, and bottles 
were appended to them in living dogs, so as to catch the pan- 
creatic fluid: it was found ropy, insipid, and like the saliva. 
It has therefore been concluded, from the colour, structure, 
ducts, and secretion of the pancreas having so strict a resem- 
blance to those of the parotid and submaxillary glands, that it 
is of the nature of the salivary glands of the mouth. The 
general opinion has been, that it is useful in secreting a fluid 
which dilutes and moderates the acrimony of the bile. More 
accurate chemical examination of the pancreatic fluid has not 
been made, or has not been successful in showing any pecu- 
liarity in it. 
Considering the pancreas as a salivary gland, how great 
must be the quantity of fluid poured out by it, if, as we are 
entitled to do, we take the analogy of the parotid, submaxil- 
lary and sublingual glands. These salivary glands, although 
they may be said to surround all the jaws from the zygomatic 
process on either side, are nothing in massiness and size to the 
pancreas. Again, the pancreas is most plentifully supplied 
with blood-vessels. Besides lesser branches of arteries, the 
pancreatico-duodenalis gives two branches, which take an ex- 
tensive course through it, and are joined by other mesenteric 
twigs ; and twigs proceed from the vessels of the stomach, and 
even from the hepatic artery; but more particularly we have to 
observe the large branches bestowed upon it by the splenic 
artery, where it takes its course close upon it. 
While the masticators are working, the parotid gland pours 
out so great a quantity of saliva, says M. Helvetius, that it is 
inconceivable, and what I should not believe, had I not seen 
it in a soldier of the guards. A cut with a sabre in the cheek 
had opened the salivary duct: the wound healing on the inside 
of the cheek left a fistulous discharge from the parotid duct. 
When he eat, there flowed from this hole a great abundance 
of saliva: so that during dinner, which is not long in the Hotel 
Dieu, it moistened several napkins. How much must flow 
from all the salivary glands ? How much from the pancreas, 
which is greater than them all collectively ? 
The pancreas being supplied with arteries from the splenic 
artery and duodenal artery, it must partake of the increased 
circulation of blood, while this system of vessels is excited by 
the fulness of the stomach. By this it must be prepared with OF THE PANCREAS. 
257 
an increase of secretion proportioned to the food passing the 
pylorus. 
Like the biliary secretion, it is probable that the contents of 
the stomach passing the duodenum, or the bile flowing from 
the biliary ducts, form the stimulus to the discharge of the 
pancreatic fluid ; and as we see that the morsel in the mouth 
will quickly produce an almost instantaneous secretion and 
discharge of saliva, so we are led to conclude that the flow of 
pancreatic fluid may be as suddenly produced without the ne- 
cessity of a reservoir, as in the biliary system. We naturally 
conceive that the effect of this fluid is to diminish the viscidity 
of the bile,and by diluting it to mix it uniformly with the food. 
There are however few facts to enable us to reason on the ef- 
fects of the pancreatic fluid. If we give full credit to the ex- 
periments of Malpighi and Brunner we may conclude, that 
when the pancreas is taken away, the more acrid bile causes 
vomiting or voracious appetite by its stimulus. Scirrhus of 
the pancreas has been found attended with a costive and slow 
motion of the intestines ; which seems to contradict the result 
of these experiments on animals ; but by the scirrhosity and 
enlargement of the pancreas the biliary ducts may have been 
more or less compressed, and the retarding of the usual quan- 
tity of the biliary secretion might produce the slowness of the 
bowels.* 
On the whole, I am inclined to think that the pancreas is a 
gland of dilution, merely that the flow of its secretion will de- 
pend on the state of the food or of the bile passing the duode- 
num. That, as in drinking, the saliva is not excited to flow, 
neither is the pancreatic fluid, when the matters descending 
through the duodenum are bland and liquid, but when they 
require dilution this gland is ready to afford it. 
* According to the hypothesis of Silvius, the use of the pancreas was to 
supply an acid spirit or juice, and the biliary secretion being of the nature of 
an alkali, these two struggling together caused the separation of the chyle 
from the faeces. The struggle did not stop here, but these enemies being 
carried into the blood continued their warfare in the heart itself, and lighted 
up the vital flame there. 
Nay, if we believe the experiment of F. Schuyl, (de Veteri Med.) this hy- 
pothesis was not without its proofs : for having tied in the portion of the duo- 
denum of a living dog, where the pancreatic and biliary ducts enter, he saw 
the ebullition from this struggle of the acid and the alkali; and when he com- 
pressed the hepatic duct, the tumefaction of the intestine subsided; when he 
took off this compression it was again blown up. As this experiment has not 
succeeded since, as Haller observes, Schuyl was probably deceived by the pe- 
ristaltic motion of the intestines, 258 
Ol' THE SPLEEN. 
SECTION III. 
OF THE SPLEEN. 
The spleen is a viscus of an irregular, oval figure, and dark 
purple colour. It is attached to the great extremity of the sto- 
mach. It is soft in its substance ; and has the peritoneal coat 
very delicate. We should bd glad could we say with the old 
anatomists that it is of a parenchymatous structure, for in truth 
little is known of its organization. 
In treating of this subject we must be indulged in some 
speculation ; and indeed it is privileged ground ; for the his- 
tory of the opinions regarding the supposed function of the 
spleen is full of loose conjectures or wild hypotheses, and no- 
thing is as yet certainly known of its use. 
The spleen is seated in the left hypochondrium ; above the 
left kidney ; and under the protection of the false ribs ; and ol 
course it is under the edge of the diaphragm. It is connected 
with the stomach by the cellular membrane, by the omentum, 
and in a still more particular manner by the vasa brevia. It 
has also connections with the left extremity of the pancreas 
by cellular membrane, and the branches of the splenic vessels. 
Lastly, it has a firmer attachment to the diaphragm, by means 
of a ligament formed by the peritoneum.* 
The spleen is of an irregular figure. Where it is contiguous 
to the diaphragm it is uniformly convex : towards the stomach 
its surface, while it is hollowed out and concave, presents two 
sides, so that we say the whole mass is somewhat of a triangu- 
lar form. The anterior edge of the spleen is notched with 
deep sulci; behind, and at the upper part, the margin is large 
and round. 
The substance of the spleen is the most spongy, tender, and 
soft of all the abdominal viscera; so much so that not only 
does the finger make an impression upon its surface, but it ac- 
tually disorders and tears its vessels.f After a successful injec- 
SEAT AND CONNECTIONS. 
* Yet the spleen is very apt to change its situation, or to fall down from 
under the protection of the false ribs. It is liable to enlargement. From 
which circumstances it will not be wonderful if it is wounded in tapping for the 
ascites. See Monro on Dropsy. Lienis a statu suo devirationes, Sandifort, 
Thesaur. Vol. iii. L. Baader observationes varix. Albinus Acad. Annot. lib 
vii. cap. xiv. 
11 have seen death from rupture of the spleen, by a wound which never 
penetrated the abdomen; a pistol shot entered the chest and struck the dia. 
phragm without piercing it; the lad died with effusions in the belly; and or 
examination, the spleen was found burst by the contusion. OF THE SPLEEN. 
259 
tion the whole seems made up of vessels ; and if any thing like 
acini or globules are to be observed, the microscope will show 
them to be accidentally produced by the fasciculi of vessels. 
By injecting the vessels of the spleen with wax, and corroding 
it, granules of wax are seen on the extremities of the veins as 
if they had filled cells. The cellular texture uniting the ves- 
sels ol the spleen, assume a remarkably stellated appearance. 
Upon the whole, this viscus has a resemblance to the substance 
ol the placenta. Fne spleen is seldom smaller than natural; 
often greatly enlarged.* I have seen it equal to the liver in 
size, and filling the whole left side of the belly. It has been 
frequently found thus enlarged, without any peculiar symptoms 
indicating such a disease during life. From its soft texture 
and great vascularity, like the liver, it has been found rent by 
blows and falls ; and wounds here, as in the liver, by opening 
the large \essels, are suddenly fatal, j Sometimes it is hard and 
scirrhous ; it is subject to inflammation, to ossification, and to 
nave tubercles formed in its substance. I here is seldom sup- 
puration in it. The spleen has been observed to swell up and 
enlarge w hen the stomach is empty, and to be contracted 
when it is full. It has been observed, that it is large and spongy 
in those who have died a lingering death, or who have been 
long ailing: that, on the contrary, it is smaller and firm in 
those who have died suddenly a violent death. 
We are informed, that the blood of the splenic vein is 
peculiar, insomuch as it does not coagulate like the blood in 
the other veins of the body.:}: 
i hat which more than any other circumstance excites our 
attention, is the great size of the blood-vessels of the spleen. 
Both the splenic vein and the artery are of great size in pro- 
portion to the bulk and weight of the spleen ; and in their 
course they are particularly tortuous. I conceive we may also 
draw consequences from the distribution of their branches to 
the stomach (viz. the vasa brevia and left gastro-epiploic) and 
to the pancreas. Its lymphatics are numerous. It is supplied 
.vith neives, but has very little common sensibility. It has no 
excretory duct. 
Professor Coleman made experiments on dogs, and found 
aiat wnen they were deprived of the spleen they became fat 
and indolent. An old pupil has lately given me an account 
of his cutting off the spleen in a native of South America. The 
* For Verities see Morgagni Advers. iii. Animad. xix 
T I have known a musket ball, striking the spleen but not penetrating the 
abdomen, prove fatal in consequence of extravasation. 
* V* this point 1 have no opinion, having hitherto neglected to 
examme the fact. J lie experiments of Sir Everard Home countenance the 
opinion. 260 
»F THE SPLEEN. 
spleen escaping from a wound had become gangrenous. He 
could observe no effect to result from this extirpation. 
Opinions regarding the use of the spleen.—Of the 
various uses of the spleen, the lowest conjecture in respect to 
ingenuity or probability is, that like a sand-bath it foments the 
stomach, and promotes the process of digestion. This notion 
is, perhaps, not inferior in absurdity to that opinion which 
ascribed to the spleen the office of forming an acid juice, which 
being carried by the vasa brevia into the stomach, was supposed 
to excite the appetite.* 
It was a better conception that the spleen is the seat of me- 
lancholy ; “ that moping here doth hypochondria sitor of 
“ laughter holding both his sides,” of which the holding of the 
sides was an evidence. And again, since tickling the ribs is a 
demonstration of the effect from this excitement of the spleen,f 
that the growth of the spleen promotes laughter to such a de- 
gree, that it becomes a permanent silly simper. Nay, further, 
we have authority for the excision of the spleen from those 
who are otherwise incurable in their propensity to laughter ! 
The following is a theory which has been very commonly 
received. A great quantity of blood is imported into the 
spleen with a slow motion, owing to the serpentine course of 
the vessels. When the stomach is empty, the blood is received 
in a greater quantity by the spleen, where it has an opportu- 
nity of stagnating. Here the blood, fomented, attenuated, 
and in a manner dissolved by the neighbourhood of the putrid 
faeces in the colon, enters upon the first stage of putrefaction. 
By this resolving of the blood it is made more fluid, in which 
state it is returned by the veins, there being no excretory 
ducts. Now when the spleen is compressed between the dis- 
tended stomach and the ribs, and the contracting diaphragm, 
the blood is pressed out from it in greater quantity and cele- 
rity towards the liver, mixing with the sluggish blood in the 
trunk of the vena portae, replenished with the fat and oil of 
the omentum, it dilates that vessel, and prevents the stagnation 
and congelation of the blood. In short, the spleen has been 
supposed to be subservient to the function of the liver, and to 
the preparation of a watery (and sub-alkaline) fluid to the 
blood of the portae. 
* I am mistaken in calling1 this the lowest in absurdity. The spleen has been 
considered as the seat of the soul! the cause of venereal appetite! the gland 
which formed the mucilaginous fluids of the joints ! The atrabiliswas received 
here, concocted and transmitted to the liver. It drew forth and formed blood 
from the stomach, &c. Other physiologists, not contented with the theories 
presented to them, and )ret incapable of suggesting others more likely, have 
very modestly asserted that the spleen was of no use at all. 
f Risus in liene sedes videtur ex effeclu titilationis nataque inplurimis mor- 
talibusrisum excitat, &c. Haller. His sober objection is, that tickling the 
right side will do as well as the left. OF THE SPLEEN. 
261 
Another opinion has been, that it counterbalanced the mass 
of the liver seated to the right side of the belly. 
Hewson entertained a theory regarding the use of the 
spleen which is injurious to his reputation. He conceived 
that the spleen added the flat vesicle of the globules of the 
blood : his only observation in way of proof was, that he saw 
a few red globules returning by the lymphatics of the spleen ; 
the effect, I have no doubt, of the injury of its substance, or if 
the compression of its vessels. It seems to me strange that 
such a man seeing the large splenic artery throwing its full 
tide of perfect arterial blood into the spleen, full of globules, 
complete in every respect, and again seeing a few globules 
carried back by the lymphatics, should imagine that this ar- 
tery formed these few vesicles with which it was already so 
fully charged. 
That the stomach, duodenum, liver, pancreas, and spleen 
are united in function, I have no doubt. Nature has placed 
them not only in juxta position, but has united them by the 
same entanglement of nerves, and has given them the same 
system of vessels. The cosliac trunk supplies them all. 
Further, I conceive the spleen to be an organ subservient 
to the stomach ; and not only the constant attachment of it to 
the stomach in the human body, but the constancy with which 
it is found connected with the stomach in the lower animals, 
confirms the opinion. I regard it as a provision for giving 
the vessels of the stomach an occasional power and greater 
activity, enabling them to pour out a quantity of fluid propor- 
tioned to the necessity of the digestion. In the first place, 
let us examine the course and form of the splenic artery, and 
I think we shall find the great peculiarity of its size, and tor- 
tuous form and strong coats, a provision for occasional great 
increase of power; while, if not roused by the peculiar sym- 
pathies which actuate it, it is of a form to retard and weaken 
the velocity of the blood. This is founded on these propo- 
sitions : 
1. The muscular power of an artery increases as it recedes 
from the heart; the elastic power diminishes. 
2. An artery, the nearer it approaches to its final distribu- 
tion, is the more immediately under the excitement and con- 
trol of the organ ; is active when the organ is excited ; is, re- 
latively speaking, quiescent when that organ is not called by 
its sympathies to exercise its function. 
3. An artery tortuous in its course has more muscularity 
and greater power of action than one which takes a straight 
course : but in proportion to the increase of power which it 
obtains by its increase of length in this tortuous and bending 262 
OF THE SPI.EEX. 
course, will these turns retard and weaken the force of the 
heart upon the extreme ramifications of the vessel. 
Thus a tortuous artery is the means of increasing the velo- 
city of the blood by its own action, but it makes the organ less 
dependent on the general force of the circulation. We ac- 
cordingly find, that in those organs where there is occasional 
activity alternating with a quiescent state, the artery is tortu- 
ous ; and where there is an increase of force required in the 
circulation, there the artery, from being straight in its course, 
becomes crooked and twisted in every way.* 
From .these remarks, we may be inclined to draw, from the 
tortuous figure of the splenic artery, a conclusion somewhat 
different from that which has hitherto been deduced. We 
may conclude, that it is not the means of retarding the blood 
in its circulation, but of giving force to it. The splenic artery 
does not only ramify in the spleen, but it supplies all the left 
part of the stomach, and that great sacculated extremity in 
particular which receives the food, and in which the process 
of digestion is chiefly performed. My idea is, that when the 
stomach is empty, w'hen there is no food in it to solicit the dis- 
charge of the gastric fluid, the blood circulates in a moderate 
degree in the coats of the stomach, and the spleen receives the 
surcharge of blood ; but when a full meal is taken into the 
stomach, when the action of the gastric juice is required in 
great quantity, the action of the splenic artery is solicited to 
the vasa brevia and left gastro-epiploic artery, and thus a sud- 
den flow of the gastric fluid is bestoAved by the increased ac- 
tivity of the splenic artery. When again the contents of the 
stomach are fully saturated writh the fluids from its coats, there 
is no longer an excited action of the splenic vessels, and the 
artery terminating in the A'eins, the spleen returns the blood 
to the liver. While the vessels of the stomach partake largel) 
of the supply of blood, the arteries to the pancreas also re- 
ceive some increase of activity; and even the blood of the 
Arena portse requires an additional activity. 
I leave this opinion of the vascular system of the spleen as 
expressed in former editions, and with the conviction that I 
have assigned one use of the splenic vessels, and afforded an 
explanation of their tortuous form ; but these remarks do not 
explain the structure of the body of the spleen. 
* This has been supposed to be the effect of the impulse of the blood, but 
nothing can be more false. Let any one examine the artery of a limb when a 
great tumour is growing; the artery will be found tortuous to supply it. Again, 
in the ancurismal varix where there is a breach in the artery, and the blood 
finds a freer return to the heart, the artery will be found enlarged and tortuous 
in order to supply the lower part of the limb ; while there is a quantity of the 
blood withdrawn from the circulation by the communication with the vein. OF THE KIDNEY. 
263 
I hat tnere are cells in the spleen is very generally believed, 
and that some operation connected with the economy is per- 
formed there is also a general belief. Sir Everard Home 
vras of opinion at one time that the spleen drew the fluids from 
the stomach, and delivered them into the circulation. But 
finding that infusions of rhubarb got into the circulation from 
the stomach when the pyloric orifice was tied, and the spleen 
taken away from the animal, he gave up that opinion. But 
he has made experiments which lead to the belief that a se- 
cretion is poured into the cells of the spleen, but for what pur- 
pose these cells or this secretion is still conjecture. 
The probability is, and it amounts to no more, that the ve- 
nous blood of the spleen is useful in the function of the liver. 
Either it may supply venous blood in proportion to the wants 
of the liver, or in that venous blood carried to the liver, there 
may be some peculiar change wrought by the spleen, and fit- 
ting it for the secretion of bile. 
SECTION IV. 
OF TIIF. URINARY ORGANS OF THE KIDNEY. 
i he kidneys are distinct from those parts which have hitherto 
engaged us, as they secrete the urine, and form therefore the 
hnk betwixt the viscera of the abdomen, and those of the pel- 
Vls ; for though lying in the abdomen, they are more strictly 
connected with the parts in the pelvis. The structure of the 
kidney forms a very interesting subject of inquiry ; because it 
is the field of dispute betwixt the contending parties regarding 
the structure ol the glands and the theory of secretion. It is 
chiefly from the kidneys that the facts are drawn in illustration 
of the opinions of Malpighi, Ruysch, and all the others. 
. Form, seat, and connections.—The kidneys lie on each 
sice of the spine ; sunk as it were in the fat of the loins ; at- 
tached to the muscles of the loins ; and in part lying on the 
.ower belly of the diaphragm; which last connection is the 
cause of the pain felt in respiration during inflammation in the 
kidney. The kidney lies betwixt the spine of the ilium and 
the lowest rib. The right kidney is placed somewhat lower 
than the left, which is owing to the greater size of the liver on 
that side. 
The kidneys are without the abdomen, that is to say, behind 
the peritoneum; for the kidney lying close upon the muscles 264 
OF THE KIDNEY. 
of the loins, the peritoneum is merely stretched over it. This 
is the reason why calculi in the kidney have wrought themselves 
out by fistulas in the loins ; and it is the ground of the hazard- 
ous proposal of cutting into the kidney to extract calculi. 
The adipose membrane surrounds the kidney, and forms a 
kind of capsule ; for it is this which is sometimes in an ex- 
traordinary degree loaded with accumulated fat. Upon this 
capsule the cascum is attached on the right side, the colon on 
the left, and betwixt the kidneys and the intestines there is a 
strict sympathy, which is apparent in the nephritic colic. The 
proper coat of the kidney is fine, dense, and firm, and closely 
surrounds its proper structure. 
The figure of the kidney is that of an oval bent, or a lit- 
tle incurvated, so as to form a sulcus or general concavity to 
one side, while the other takes a greater convexity. By the 
concave surface of the kidney, w'hich is towards the spine and 
great vessels, the arteries and veins and ureter pass in by the 
sinus, round which the substance or glandular body of the kid- 
ney terminates abruptly. 
The abdominal aorta and the vena cava lying close on the 
spine and near to each other, give off laterally the emulgent 
arteries and veins. The renal or emulgent artery comes from 
the side of the aorta betwixt the upper and the lower mesente- 
ric arteries : that of the left kidney has its origin a litle higher 
than the right: and the aorta being on the left and the cava 
towards the right side of the spine, the left emulgent artery is 
shorter than the vein ; the artery longer than the vein on the 
light side. Again, the aorta being more closely attached to 
the spine, the emulgent vein lies rather above the artery.* 
The vessels, and especially the arteries of the kidney, are 
very irregular in their number and form. Where they enter 
the body of the gland, they are accompanied with a capsule 
which continues with them to their final distribution. Some- 
times a solitary vessel is seen making its exit by the convex 
surface of the kidney. 
We have had occasion to remark on the nerves of the kid- 
neys and their connection with the coverings of the testicle, 
and to notice their effect in producing numbness of the thigh 
and retraction of the scrotum in inflammation of the gland, 
when stones lodge in the pelvis or ureter. 
Upon the subject of the sensibility of the kidney, however, 
we must be aware that disease, inflammation, suppuration, nay 
* The vessels of the kidney vary greatly. C. H. Meuder de uriflae excr?* 
tione, Sandifort, Thes. vii.—Albinus Acad. Annot- b. vii. c ii. OF THE KIDNEY. 
265 
even total wasting of the kidney may take place without any 
indication from pain. 
The excretory duct of the kidney is called ureter : it leads 
from the kidney to the urinary bladder. When we trace it 
backwards into the kidney it is found to enter the sinus of the 
kidney. Here it is enlarged into a considerable sac which is 
called the pelvis of the kidney. This is a kind of reservoir 
which, lying in the embrace of the solid and glandular part of 
the kidney, sends up several elongations like the finger of a 
glove. These are called infundibula. They are indeed like 
funnels, for they expand to receive the papilla of the kidney 
from which the urine distils. 
It may be observed, however, that the term pelvis is taken 
from the greater dilatation of the ureter within the gland, 
which is seen in brutes; and that in man it is not so remarkable, 
the ureter branching with only a lesser degree of the sacculat- 
ed form into three or four divisions, and these into the infun- 
dibula.* 
The coats of the ureter are three in number; a dense outer 
coat; a middle coat apparently consisting of circular muscular 
fibres, though this has been denied ; and a smooth inner coat, 
(very improperly called villous,) which secretes a mucus to 
defend it from the acrimony of the urine. The ureters do not 
run in a direct course to the bladder of urine ; they take a 
curving direction ; are in some places irregularly dilated, as 
when they pass over the psoas muscle,f dropping deep into the 
pelvis, and getting betwixt the rectum and bladder, they open 
obliquely into the latter.:}: The use of the ureter is to con- 
duct the urine which is incessantly in the kidney to 
the urinary bladder, where it can be retained and discharged 
at a convenient time, 
MINUTE STRUCTURE OF THE KIDNEY. 
Let us now attend to the structure of the gland. The an- 
cients, says Malpighi, contented themselves with the idea of 
a sieve, as conveying a knowledge of the manner in which the 
* In my Collection specimens may be seen of the pelvis in the human kid- 
ney dilated to contain some ounces. 
f When the bladder is contracted in consequence of a stone, or when it is 
dilated by obstructions, as from stricture, the ureters become dilated to the 
size of small intestines. Specimens may be seen in the Collection. 
t JVuck describes the ureters as being very irregular, and always contracted 
in three or four places. Bartholin, though he observed valves as the duct en- 
ters the bladder, and Coschwitz describes valves in their course. 
§ When a fistula of the loins communicates with the kidney the urine flows 
uninterruptedly. 266 
OF THE KIDNEY. 
urine was drawn off by the kidney; that the fibres of its pa- 
renchymatous matter attracted the serum of the blood ; that 
the fibrous matter was perforated with innumerable foramina; 
or that the whole was a congeries of canals through which the 
urine was strained and drawn off. Malpighi set himself to 
refute these vague opinions by the minute examination of the 
structure of the kidney ; and he seems to have known almost 
all that we now know. Though we do not acquiesce in his 
opinions regarding the final and minute structure, he describes 
accurately every part of the gland. 
In the first place, when we examine the outward appearance 
of the kidney of the foetus, we observe that it is not, like that 
of the adult, smooth and uniform, but tuberculated or lobulat- 
ed ; that it consists of distinct parts, or glands united to- 
gether. Again, when we examine the kidneys of other ani- 
mals, we find in several instances that the full-grown animal 
retains this lobulated form. In short, it immediately strikes 
us, that the kidney is not a uniform mass of glandular matter, 
but that it most resembles those glands which they call con- 
glomerate, and which consist of several compartments or 
distinct glands united together. 
Accordingly a section of a kidney shows us that this is the 
fact. 
Example of the Lobulated Kidney. 
The* section of the kidney shows us these parts. First, we 
see towards the surface that which is called the cortical or 
A B C D. The several divisions of the kidney which give it the lobulated 
figure. 
E E. The cortical part of the kidney, being the outer, and, it is supposed, 
the secreting part. 
* Explanation of the annexed plate. OF THE KIDNEY. 
267 
glandular part E. Secondly, stria?, converging towards the 
centre of the kidney, being what is called the tubular part of 
the kidney.* These tubuli are divided into fasciculi, taking a 
conical shape; and these converging unite at the apex; two 
or three of them united form a papilla. The papilla? are ge- 
nerally ten or twelve in number, or even more, in each kidney ; 
their points are received into the extremity of the infundibula; 
they pour the urine into these tubes, which is collected in the 
pelvis. 
When we examine one of these papillae in a lobulated kid- 
ney, we find that it is the centre of one of thes*e subdivisions. 
Thus, 
A. A. Cortical Substance. B. Tubular part. 
C. Papilla. D. Ducts. 
The papilla C is merely the continuation of the tubuli B; 
but it is that part which projects from the body of the kidney 
into the calyx or infundibulum ; and although these divisions 
of the substance of the kidney are enumerated as three distinct 
parts, the cortical, tubular, and mamillary parts, they are pro- 
perly only two, the cortical and tubular parts. 
Some however have made a new distinction, by asserting 
that a vascular part is to be observed betwixt the cortical and 
tubular, or striated parts; but it is not the case; for although, 
when we make a regular section of the whole gland, the mouths 
F. F. The tubular part of the kidney. 
G. The papilla, or that part which projects into the calyx or infundibulum 
of the pelvis. 
H. The ducts of Belini in the point or apex of the papilla. 
III. Other papillae. 
N. E. This represents only one half of the kidney. 
* Improperly medullary, sometimes striata. Winslow {trails du JJasventrc 
has these distinctions of the substance of the kidney. 1. Corticale. 2. Can 
nelle, sillonnee, ou tubuleuse, 3, Mammelonnee. 268 
OF THE KIDNEY. 
of some larger vessels may be observed betwixt the fasciculi 
of the urinary tubes, yet they are irregular ramifications tend- 
ing to the outer cortical part, g.nd not such as separate the 
tubular and cortical part, nor so regular as to be considered 
as one of the subdivisions of the kidney. 
OF THE CORTICAL PART. 
The external and cortical part of the kidney is by all allow- 
ed to be the secreting, or, as they rather term it, the secerning 
part of the organ. It was this part which the older writers con- 
sidered as in a more particular manner to consist of a peculiar 
■fleshy substance, or parenchymatous matter. It is in this cor- 
tical matter that the glandular bodies described by Malpighi 
are supposed to be seated; they are called corpora globosa. 
They are to be very distinctly seen in many brutes ; for ex- 
ample, in the horse’s and cow’s kidney ; and they are to be 
seen represented in these plates. But he asserted these bodies 
to be also observable in the human kidney ; to demonstrate 
which he injected a black liquid mixed with spirit of wine, by 
which the kidney becoming universally tinged, you may then 
see, he said, when you have torn off the coats of the kidney, 
small glands partaking of the colour of the arteries. These are 
the glands of the cortical part of the kidney, which Malpighi 
described as hanging upon the branches of the arteries like 
fruit upon the pendant branches, and round which the arte- 
ries and veins ramified and convoluted, like delicate tendrils, 
so as to give them the dark colour which they have. 
Into these bodies he supposed the urine to be secreted, and 
that from these bodies it was conveyed into the uriniferous 
ducts or tubular part of the kidney; but he acknowledges 
that the communication betwixt the ducts and glands is verv 
obscure. 
Ruysch and Vieussens held a very opposite opinion re- 
garding the structure of the kidney.* Ruysch, by throwing 
his injections into the renal arteries, found that he filled the 
urinary tubes, the ducts of Belini, and the pelvis itself. 
Hence he conjectured that the tubuli uriniferi or excretory 
ducts of the kidney were the continued branches of the renal 
artery, without the intervention of any glandular apparatus*! 
* Ruysch and Vieussens long contended for the claim of the discovery of 
the continuation of the arteries of the kidney into the urinary ducts. Ruysch 
at first acquiesced in the opinion of Malpighi, as we have said, 
f Thes, Anat. ii. p.31. OF THE KIDNEY. 
269 
Example of Ruysch’s doctrine.* 
Ruysch’s Plate. 
Ruysch did not neglect the examination of the little bodies 
which are to be seen in the cortical substance. He did not 
however allow they were glands, but confidently asserted that 
they were merely the convoluted arteries which were formed 
into these contorted bundles before finally stretching out, and 
terminating in the straight urinary tubes.f 
* Exhibet renis humani dimidiam partem ita dissectam, ut reptatiis vasorum, 
presertim sanguineorum, loculentius quam in precedent! Thesauro, tab. iv. fig. 
jii.videre possit; ubi magis inherebam, ut conjunctionesarteriolarum cum duc- 
tibus Belini exhiberem, in hac autem figura distinctissime vasorum sangui- 
neorum cursum vermicularem per interiorem renis partem exprimere volui. 
A. Facies renis exterior perquam vasa sanguinea reptatum observant ver- 
micularem. 
B. Facies renis interior ubi vasa sanguinea non minus cursum vermicula- 
yem observant quam in facie exteriore. 
C. Papillae renales. 
D. Pelvis renis. 
E. Cavitas pelvis in quam papillae urinam stillando exprimunt.—See The- 
saur. Anat. W. p. 27. 
f In hoc Thesauro X. quoque inveniuntur objecta renalia ex homine de- 
sumpta, in quibus non solum luculenter apparet quid judicandum sit de prae- 
tensis glandulis renalibus, verum etiam quid investigatoribus renum imposue- 
rit, se in renibus indagandis saepissime occurrunt corpuscularotunda glandulas 
mentientia quae revera nil sunt nisi arteriolarum ultimae extremitates contortae; 
cum autem exactissime repleantur arteriae renales dissolventur vel expandun- 
tur, quemadmodum fili glomer, ita ut nil minus sint, sicuti dixi, quam partes 
per se subsistentes & peculiari membranula obductae sine quo immerito dicun • 
tur glandule, Interim considerandum ejusmodi contorsiones vasorum sang 270 
OF THE KIBNEY. 
When after minute injection of the kidney we make a sec- 
tion of its whole substance, we see vessels emerging from the 
more confused intricate vascularity of the cortical part, and 
running inward in striae towards the papillae; what we see there 
are, in my conception, chiefly veins. And this I conclude, 
both from the result of injections, and from knowing that the 
veins are in general numerous surrounding the excretory ducts; 
besides they retain the blood in them like the veins. These 
vessels running in straight lines and converging towards the 
papillae are not the tubuli uriniferi, but the blood-vessels ac- 
companying them, the tubes themselves being transparent. 
Yet I imagine it was by these vessels that Ruysch was de- 
ceived ; for tracing them from the extreme arteries, and see- 
ing them suddenly altered in their form and direction, and 
running towards the papillae, he imagined them to be the ex- 
’cretory ducts continued from the extreme branches of the ar- 
teries. 
Winslpw supposes the corpuscules, which are seen in the 
cortical part of the kidney, to be the extremities of the cut 
tubuli filled either with blood or with a coloured injection. 
But this they evidently are not; for by making the substance 
around them transpai-ent, they are seen within the surface, 
and they are little grains, not the extremity of tubes, nor ex- 
tended in lines. 
Boerhaave, although he saw in the preparations of Ruysch 
the injection passed into the uriniferous tubes, yet in the main 
favoured the opinions of Malpighi; and having sometimes ob- 
served these tubes filled with injection, while at intervals they 
were transparent or pale, and contained only a watery fluid, 
he ventured to conclude that there was a double operation 
going forward in the kidney; that the pale watery urine was 
quickly drawn off, by the continuous tubes ; but that the urine 
of the other quality and higher colour separated by a more 
perfect and slower secretion through the glandular bodies. 
In the history of opinions, to Boerhaave succeeds Bertin, 
who writes a long and laboured paper in the memoirs of the 
Academy of Sciences for 1744; upon the whole, he may be 
considered as endeavouring to prove by dissection what "was 
rather an hypothesis with Boerhaave. Bertin describes glands 
in the substance of the kidney; but these he is careful to dis- 
tinguish from the corpuscules of Malpighi, which he also con- 
ceives to be the extremities of vessels merely. 
nusquam in ceteris visceribus rcperiri. In the epist. to Boerhaave, p 77, we 
find Ruysch speaking much more modestly : “ In rene humano rotunda corpus- 
cula esse, fateor, sed sunt tarn exilia, ut nihil possim definire de illis. Adeo- 
que non licet magisdicere quod sint glandule, quam aliud quid.” OF THE KIDNF-l . 
271 
.1/. Buriiiis Plate. 
From this plate we shall easily understand Bertin’s descrip- 
tion. He observes, in the first place, that there are to be seen 
serpentine vessels, such as Ruysch described : for example, at 
A A A,* which arising at the circumference of the cortical 
substance, are reflected inward in a tortuous form, and which, 
at last, approaching the tubular part, terminate in straight- 
tubes, or are continued into the tubuli uriniferi (for example 
at B B.) 
But betwixt the meshes of vessels which are described, and 
which are seen here to terminate in the tubuli, there are beds 
of glands C C C, which acervulas of small glandular bodies 
are as it were laid in the tract from the circumference towards 
the centre, and appear to terminate or to be connected with 
the tubuli uriniferi as the arteries are. 
M. Ferrein has opposed all these opinions in a paper of the 
Academy of Sciences for 1749. He asserts that the body of 
the kidney is neither composed of glands nor a congeries of 
blood vessels ; that it is a peculiar substance, which when ex- 
amined is found to consist of transparent vessels. These, he 
says, are wonderfully convoluted in the cortical part of the kid- 
ney, so as to resemble glands, and stretch in parallel lines to- 
wards the papillae, where they form what is called the tubuli uri- 
niferi. Amongst these transparent tubes the blood-vessels ra- 
mify to great minuteness, and accompany them where they are 
* Mesches de M. Winslow ou vaisseaux spong-ieuses de Vieussens oa tuyaui 
erpentans de Ruysch. 272 
or th£ kidney. 
reflected directly inward to form the tubuli. Muchridicule- he 
observes, has been thrown upon the term parenchyma of the 
ancients ; but notwithstanding he affirms, that there is in all 
glands a substance dissimilar from the blood-vessels, a gela- 
tinous-like matter, which consists of or contains these pellucid 
tubuli. 
Tubular part.—The term here used is universally receiv- 
ed ; and all seem agreed that the striae converging to the cen- 
tre of the kidney, and taking a pyramidal shape, are the excre- 
tory ducts. We have seen that they were supposed by some 
anatomists to be formed by the continuation of the extreme 
branches of the arteries ; but this opinion we shall venture to 
say arose from the appearance of the blood-vessels injected, 
which lie parallel and close to them. They are evidently 
transparent tubes, and probably the fibrous appearance of the 
whole pyramidal body formed by them is owing to the accom- 
panying blood-vessels. These lesser ducts, as they approach 
the papillae, terminate in larger ducts, which finally open into 
the ducts of Belini at the point of the papillae. The pa- 
pillae we have seen to be that part of the pyramidal body which 
projects into the calyces or infundibula, and from their point 
little dreps may be perceived to form when they are com- 
pressed. This fluid comes from the ducts of Belini. 
I have detailed the several opinions regarding the structure 
of the kidney; and neither do I wish here to vamp up an 
opinion from the aggregate of these contradictory reports, nor 
have I been able to draw a decided conclusion from my own 
experience. In truth, the observation from one dissection I 
have hitherto found so completely contradicted by other ex- 
periments, that I must conclude there yet remains much to be 
done in investigating the piinute structure of the glandular 
viscera.* 
OFFICE OF TIIE KIDNEYS. 
The kidneys secrete the urine : but this drawing off of the 
fluid from the system is not the sole object of the secretion; 
the water conveys away certain matters in solution. As the 
urine contains more saline matter than any other secretion, vre 
are led to suppose, that the kidney is of use to rid the system 
of these saline substances. 
These principally consist of the muriatic salts, as the muriate 
of potash and soda, the phosphoric salts, as phosphate of sods 
* Of the kidney ranch in Morgagni Advers- Anatom, ii;. OF THE KIDNEY. 
273 
of lime, and ammonia ; the phosphoric and lithic acids, with 
animal extractive matter, and a gelatinous or albuminous mat- 
ter. In short, chemists have declared, that eleven substances 
are constantly present in the urine, and occasionally others, the 
product of morbid action; so that from the kidneys, much, both 
of the solid and fluid composition of the frame, must be sent 
off in that circle of action, deposition and absorption, by which 
both the structure of the frame and the qualities of the living 
body are preserved. 
OF THE CAPSULE RENALES.* 
The renal capsules are glandular bodies of a reddish yellow 
colour, one attached to each kidney. The gland is seated like 
a cap on the upper end of the kidney. It is of a form like an 
irregular crescent, and suited to the shape of that part of the 
kidney to which it is attached; at the same time that it has 
three acute edges, being something of a triangular form.— 
The upper edge has been called crista, while the lower edges 
have the name of lobes. It is in the foetus and in childhood 
that the renal capsule is large and perfect; in the adult it has 
shrunk, and no longer bears the same relative size to the kid- 
ney. In the foetus the renal capsule is as large as the kidney, 
and the capsules of each side are continued into each other, 
being stretched across the aorta and vena cava.f 
The vessels sent to this body are somewhat irregular; they 
come from the renal or emulgent arteries and veins, from the 
coeliac artery or phrenic, or from the trunk of the aorta, and 
even from the lumbar arteries. 
By separating the lobes of this body we find something like a 
cavity, which has been roundly asserted by some to be a regu- 
lar ventricle; by others altogether denied. Finding a cavity, 
they supposed they must discover the excretory duct. Some 
conceive that it must be connected with the pelvis of the kid- 
ney ; some with the thoracic duct; some with the testicle; but 
every thing relating to the use of this body has hitherto eluded 
* Glandule atrabilarie, reties succenturiate. Glandule renales, &c. 
f For various authorities on the size and appearance of this body, see Mor- 
gagni Epist. Anatom, xx. 274 
OF THE KIDNEY. 
research, and all is doubt and uncertain speculation.# For 
my own part I conceive that this body is useful in the foetus, 
by deriving the blood from the kidney, that gland not then 
having undertaken its proper office of secreting the urine. 
* Morgagni Adversar. An. iii. A. xxxii. 329. Valsalva is reduced to the 
necessity of quoting Scripture, and Morgagni is as much at a loss, Epist. Anat. 
XX. being obliged to join in the words of Eustachius: “iis relinquamus, qui 
anatomen acuratus exercent, inquirendum.” Morgagni, loc. cit. THE 
OF THE 
MALE PARTS OF GENERATION. 
AS there is no very accurate division betwixt the viscera 
of the abdomen and those of the pelvis; as the uterus and 
bladder, being viscera of the pelvis, rise into the belly when 
distended, and are in every respect like the abdominal vis- 
cera, many have objected to a division of the viscera of the 
abdomen and pelvis: nevertheless, there appears to be good 
reason for this division of the subject. The function of the 
parts is different; the manner of their connection is different, 
and their diseases have widely different effects. 
We. have seen that the pelvis consists of the sacrum, or 
coccygis, and ossa innominata, and that anatomists have dis- 
tinguished the true and the false pelvis. The false pelvis is 
formed of the extended wings of the ossa ilii, and supports the 
viscera of the abdomen. The true pelvis consists of that 
cavity which is beneath the promontory of the sacrum and the 
linea innominata ; it contains, in man, the rectum, the urinary 
bladder, the prostate gland, the vesiculse seminales, and part 
of the urethra. In woman it contains the rectum, vagina, 
uterus, Fallopian tubes, ligaments of the uterus and ovaria. 
The manner in which the parts of the male pelvis are con- 
nected, and the anatomy of the urinary bladder, prostate 
gland, and urethra, will form the subject of the first section, 276 
or THE PARTS WITHIN THE PELVIS. 
while the anatomy of the parts connected with those of the 
pelvis in function, but seated without, will form the subject 
of the second. 
CHAP. III. 
OF THE PARTS WITHIN THE PELVIS. 
We have seen that the abdominal viscera are involved in a 
common membrane; that this membrane is uniformly smooth; 
and that it has a secretion on its surface which bedews the 
whole, and allows the parts an easy shifting motion on each 
other. The parts in the pelvis must also have motion, but 
they are at the same time more intimately connected; a loose 
cellular membrane is the medium of adhesion here: the parts 
are imbedded in cellular membrane which is interwoven with 
muscular fibres towards the lower opening of the pelvis, and 
further braced by the levator ani and muscles of the perineum. 
This gives to the whole due support; enabling them to resist 
the compression and action of the abdominal muscles, which 
they must receive in common with the higher viscera of the 
belly. 
By turning to the first plan in this volume, we find, that the 
division of the parts in the pelvis and abdomen is not well 
defined; but we see that the peritoneum is reflected from the 
pubes over the urinary bladder, and mounts again upon the 
rectum. The line of division, therefore, is the peritoneum ; 
while we understand how the bladder which belongs to the 
pelvis, being distended, carries the peritoneum before it, and 
rises into the abdomen. 
SECTION I. 
OF THE BLADDER OF URINE. 
The bladder of urine must be classed with membranous or 
hollow viscera. It is a bag or receptacle into which the urine of the bladder of urine. 
277 
slowly distils through the ureters, that it may be expelled at 
convenient seasons. It is nearly of a regular oval, when mo- 
derately distended, the ends being obtuse; but from its connec- 
tions, and the pressure of surrounding parts, this regular exten- 
sion is not allowed in the living body. When seen moderately 
distended in situ, it rises somewhat pyramidal upwards, it is 
flat upon the os pubis on the forepart, and towards the back 
and lower part a portion may be seen somewhat sacculated, 
and below the level of the commencement of the urethra. 
We describe the body, fundus, neck, and lateral parts. The 
fundus is the upper part; the neck is where the urethra com- 
mences, and where the prostate gland is attached ; the lateral 
part is, where being distended it stretches at its lower part to 
the sides of the pelvis. 
On the fundus there is a ligamentous process, continued in 
a direction towards the umbilicus ; this is I would 
not mention it here, being a tube peculiar to the foetus of quad- 
rupeds, was it not to add that it is sometimes even in the 
adult human subject open, so that the urine passes out from 
the umbilicus.* 
When the bladder is empty, or contains only a moderate 
quantity of urine, it takes a triangular figure in the dead body, 
the base of which rests on the rectum, and the apex is attached 
to the back of the os pubis ; and when in dissection you look 
down into the pelvis, you find the back part of the bladder 
flat, and as it were stretched obliquely up upon the os pubis. 
Structure of the bladder.—Like the other hollow vis- 
cera, the bladder consists of several coats. 
The peritoneal coat of the bladder does not surround the 
bladder, but only covers the fundus and back part-. It is like 
in every respect to the peritoneal coat of the abdominal vis- 
cera ; smooth without; and adhering to the inner coat by cel- 
lular membrane ; which cellular membrane is, however, of a 
looser texture, and in greater quantity than under the perito- 
neal coat of the abdominal viscera. This peritoneal coat is 
no doubt of much service, as a division in obstructing the 
course of inflammation arising from the diseases in the lower 
part of the pelvis, or from operations performed on the blad- 
der, rectum, or perineum ; were it not for the loose peritoneum 
spreading over the cellular texture of the pelvis, we could nei- 
ther be so bold nor so successful in our operations here. That 
portion of the peritoneum which covers the back part of the 
* Femelius depart. morb. & symptom, gives an example of a man who, having 
an obstruction at the neck of the bladder, passed his urine by the umbilicus. 
Wepfer gives a similar case of a man with calculus. These are quoted by 
Minus Jlnnot. Acad, and also the Philos. Transactions, n. 323. See also Sandi- 
fort Thes. Vol. iii. p. 234—246, 278 
OP THE BLADDER OP URINE. 
bladder, forms a particular transverse fold when the bladder is 
contracted. This fold surrounds the posterior half of the 
bladder, and its two extremities are stretched towards the side 
of the pelvis, so as to form a kind of lateral ligament.* 
Though in the contracted or moderately distended state of 
the bladder, the peritoneum stretches from the back of the os 
pubis to the bladder, the distention of the bladder, in an im- 
moderate degree, raises the peritoneum off from the pubes, so 
that the bladder can be struck w ith a trochar, or lithotomy 
performed above the pubes, by an incision directly into the 
bladder, without piercing the outer or peritoneal coat. 
Towards the lower part, the bladder, as wre have seen, is 
invested only by cellular membrane, which takes the place of 
the peritoneal coat of the fundus. This tissue is very loose, 
and permits the distention and contraction of the bladder, 
which looseness.of texture is a matter of regret, when blood 
or urine is forced.into this tissue. 
Muscular coat.—The muscular coat of the bladder is very 
strong. Three strata of fibres are described by authors. They 
are so strong as to have been classed writh the distinct mus- 
cles, and the whole coat has been called detrusor 
Towards the lower part of the bladder the fibres are particu- 
larly strong, and formed into fasciculi, and are like a net of 
muscles inclosing the bladder.f These fasciculi acquire 
greater thickness and strength when the bladder is excited by 
opposition, as from stricture in the urethra.f 
Towards the fore and low’er part of the bladder, the mus- 
cular fibres congregate into a sort of tendon, which goes off to 
the back of the os pubis, which we count to be the insertion of 
the tendon of the bladder, and certainly this hold, which the 
bladder has upon the os pubis, causes it, in its contraction, to 
be drawn to the back of the pubes. 
We have an idea of the wonderful degree of contraction in 
the bladder, and indeed the extent of motion in the muscular 
fibre in general, when wre consider that the bladder extends so 
as to contain two pounds of urine, and contracts so as to force 
out the last drop from its cavity. When, however, the fibres 
are stretched too far, they lose the powrer of contraction, and 
often the young surgeon is deceived by what he conceives to 
be an incontinence of urine, vThile it is really an obstruction. 
The true sphincter of the neck of the bladder has hitherto 
escaped notice: it ha$ been looked for on the outside of the 
prostate gland, and then the compressor prostatse, the levator 
* See description of the folds ctf the peritoneum, 
j Morgagni Arlversar. Anat. iii. Animad. xxxix. 
i Some very remarkable examples of this may be seen in my Collection OF THE BLADDER OF URINE. 
279 
urethrse, and the levator ani, have been considered as sphinc- 
ters, and so indeed they are, inasmuch as during their action 
the urine cannot be expelled along the urethra ; but the true 
and appropriate sphincter of the bladder lies under the base of 
the prostate gland, and immediately surrounding the begin- 
ning of the urethra. 
Third coat.—This third coat of the bladder anatomists 
have called the nervous and cellular coat; it consists of very 
extensile white lamellae of cellular membrane. It gives dis- 
tribution to a few vessels, and connects the muscular fibres and 
inner coat. 
The internal coat of the bladder is very smooth on its 
general surface, and is bedewed with a sheathing mucus. 
When the bladder is distended, no inequalities are to be ob- 
served ; but when contracted, it falls into folds and rugae. 
From an- acrid state of the urine; from stranguary, from calcu- 
lus, the mucous discharge is increased, even so as to form a 
great proportion of the fluid evacuated from the bladder. No 
visible source of this mucus is to be observed on the inner 
surface of this membrane so that probably it is a general 
discharge from the surface. Indeed, it appears, that no folli- 
cules or cryptae, discharging at particular points of the surface, 
could have the effect of bedewing and defending the whole 
surface from the acrimony of the urine.f 
The ureters, which convey the urine from the kidneys to 
the bladder of urine, open very obliquely into the bladder, to- 
wards the back and lowest part of it. The consequence of 
their oblique perforation of the coats is, that, the greater the 
tendency of the urine to pass retrograde into them from the 
bladder, (there being a proportioned distention of the coats of 
the bladder,) the more their mouths are compressed. Thus, 
in the dead body, there is no degree of distention which causes 
the water to pass by the ureters. The contraction, or rather 
the resistance to distention, of the ureters and pelvis of the 
kidneys, seems much greater than the powers of the bladder 
are able to oppose ; for in obstructions of urine in the urethra 
there is still an incessant accumulation in the bladder, even 
when the bladder has increased to such a size as to be com- 
pressed by the action of the abdominal muscles. The cause 
of this yielding of the bladder to the secretion of the kidney 
is, that it has little permanent contraction, though occasionally 
its action is very great. 
* Winslow, however, describes the glands, and Ileister and Haller describe 
follicules, near the neck of the bladder, and round the insertion of the ureters, 
f When the mucous secretion is diminished by a disease of the inner mem- 
brane of the bladder, the calculous concretion more readily forms on the sur- 
face. 280 
OF THE PROSTATE GLAND. 
Corpora carnea.*—Where the ureters terminate, there are 
two fleshy bodies stretching forward, which run together near 
the opening of the urethra ; and at their meeting there is a 
prominence of the inner membrane of the bladder. From 
this prominence a line is continued forward, which terminates 
in the caput gallinaceum. These fleshy cords are muscles of 
very particular use, they restrain the termination of the ureters, 
and preserve the obliquity of the passage of these tubes 
through the coats of the bladder when it is contracted ; without 
this provision the urine would be sent retrograde into the ure- 
ters, instead of forward into the urethra.f 
The urachus does not belong to the human bladder. Itis 
a tube which, in the foetus of quadrupeds, communicates be- 
twixt the bladder of urine and the membrane called alantoes. 
But in the human foetus there is no such communication; both 
in the foetus, and somewhat less distinctly in the adult, there is 
a ligament like the remains of the duct which runs up between 
the peritoneum and linea alba of the abdomen towards the 
umbilicus. 
SECTION II. 
OF THE PROSTATE GLAND. 
On the neck of the bladder, and surrounding an inch of the 
beginning of the urethra, there is a gland nearly of the size 
and figure of a chesnut. This body is called the prostate 
gland. In all the extent of anatomy, there is not a more im- 
portant subject for the attention of the surgeon than this of 
the size, relation and connection, and diseases of the prostate 
gland. 
The shape of this body is round, at the base which is to- 
wards the bladder, pyramidal forward. It has a lateral divi- 
sion, forming it into two lobes ; and the older anatomists speak 
of it as double. Mr. Hunter and Sir Everard Home have ex- 
cited our attention to the posterior or third lobe of this gland, 
and have drawn the most important practical remarks from 
the observation of this part of the anatomy ; while the pros- 
tate gland surrounds the beginning of the urethra, it rests on 
the rectum, and it is tied by a fascia or ligament to the back 
* Corpora Carnea Morgagni. Vide Adversar. Anatom, i. 9. A.Iii. 421. Mam- 
meleon allonge Splatic/mologie,par Ji. J. C. de Garengeot. 
t See a paper by me on this subject in the 3d vol. of the Medico-Chirurg 
Trans. OF THE PROSTATE GLAND. 
281 
part of the os pubis. The urethra passes through it; not in 
the middle, but towards its upper surface ; so that the gland 
is more prominent downward, and is distinctly felt by the point 
of the finger in ano. When the catheter is introduced, and 
the surgeon examines the state of parts by the rectum, he will 
first distinguish the curve of the staff, covered with the bulb 
of the urethra : behind this the catheter will feel more bare of 
parts, but still covered with a greater thickness of parts than 
one should expect from the description of the membranous 
part of the urethra. And behind this, again, he will feel the 
prominence of the prostate gland, not round, distinct, and 
accurately defined, but gradually lost both before and behind, 
among the surrounding cellular membrane and muscular fibres 
which involve it. 
The texture of the gland is a compact spongy substance, 
and when cut has considerable resemblance to a scirrhous 
gland. From each lobe there are small follicules opening into 
the urethra, and from these the ducts may be injected.*' 
It has been said that there is really no division of this gland 
into lobes ; but perhaps the best authority on this question is 
the morbid appearance,. Now it happens sometimes that only 
one side of the gland is enlarged, which is a proof that there 
is some division betwixt the lobes. This unequal swelling of 
the gland distorts the urethra, and gives it a direction very dif- 
ficult to be followed by the catheter. In general, when equally 
swelled, the greater part of the gland, being beneath the ure- 
thra, raises it up so that the point of the catheter must be 
raised over the enlarged gland before we can pass it into the 
bladder. 
On the lower part of the gland, and betwixt the bladder and 
the vesiculae seminales, the third portion of the gland is situ- 
ated, of which Morgagni gives this account. But if any addi- 
tion is to be given, says he, to the description of the prostate 
gland, it is that roundish and smooth body like a gland which 
often our very diligent dissector has shown in the public dis- 
sections. It lies prominent betwixt the bladder and seminal 
capsules where they are united. Upon our most accurate ex- 
amination, we find this to be nothing more than a part of the 
prostate itself.f After this l ean see no objection to calling 
this part of the prostate gland Lobus Morgagni. Morgagni 
likewise observes that it is not always to be found. 
The prostate gland secretes a ropy mucus. It is probable 
* As first done by Monro. 
f Vide Morgagni Adversaria Anatomica, Animudversio xv. Prostate propage. STRUCTURE OF THE PENIS. 
282 
that this mucus serves to sheath the passages and preserve 
them from the acrid urine. It certainly unites also to the 
seminal fluid, and is discharged with it. 
The diseases of this gland form a subject too important and 
extended to be even hinted at here.* 
Anterior to the prostate gland, and also close to the ure- 
thra, are seated the glands of Cowper. This gland is also 
for the purpose of discharging mucus into the urinary passage. 
It is seated in that angle formed by the abrupt termination of 
the bulb of the spongy body of the urethra, and consequently 
close to the membranous part of the canal. It has a long duct, 
which, running forward an inch in length, terminates in the 
surface of the urethra. To comprehend the anatomy of the 
male urethra we must first notice the penis. 
CHAP. II. 
OJ the parts connected -with the Viscera of the Pelvis, but 
. seated xvithout it.—Of the Penis and Urethra.—Of the 
Testes. 
SECTION I. 
OF THE PENIS AND URETHRA. 
STRUCTURE OF THE PENIS. 
The penis consists of a spongy substance, admitting venous 
blood, and supported by a very firm elastic covering, which re- 
strains the over distention, and gives the forms. There are 
properly three spongy bodies. Two of these bodies are called 
the corpora cavernosa penis, and form the body of the pe- 
nis ; the other is the corpus spongiosum urethra, a vesicu- 
lar and spongy substance, which surrounds the whole length of 
* For much of the anatomy and the. morbid conditions of these parts, see 
Specimens of Morbid Parts, taken from the Collection of Windmill-street■ Folio- 
Longman and Co STRUCTURE OF THE PENIS. 
283 
the urethra, and expands into the bulb of the urethra in the 
peritoneum, and into the glans on the point of the penis. 
Corpora cavernosa.—The body of the penis consists of 
two tubes formed of a very strong sheath. This sheath has a 
great degree of elasticity, but at its utmost extension power- 
fully resists the farther distention with blood. These tubes are 
united in the greater part of the length of the penis, or rather 
they are parted by an imperfect partition. Within them is a 
curious tissue which forms a cellular texture ; into this texture 
the arteries pour their blood so as to occasion erection. The 
posterior extremities of these cavernous tubes are called crura 
penis: they separate in the perineum, and each of them takes 
hold on the ramus of the os pubis. Foreward, these cavern- 
ous bodies or tubes terminate in rounded points under the 
glans penis. 
This internal tissue consists of cells connected with each 
other, and having a free communication through the whole 
extent of the penis. They are interposed betwixt the extre- 
mities of the arteries and veins, or probably while the arteries 
have communication, and open into the extremities of the 
veins, in the common way: they have such connexions with 
the cellular structure, that in the accelerated or excited action 
they pour their blood into the cells ; yet in such a manner, 
that the blood circulates in the penis during erection as at 
other times, and the blood in the cavernous body is not stag- 
nant. 
Section of the penis, as inflated. 
A, Corpus cavernosum Penis. B, Septum. C, Urethra. D, 
Corpus spongiosum Minus, or spongiosum Urethra. 284 
structure of the penis* 
Corpus spongiosum urethra.—-Attached to the cavernous 
body of the penis there is a spongy body similar in structure; 
through this cellular or cavernous texture the canal for the 
urine, called the urethra, takes its course, which gives rise to 
the name spongy body of the urethra, or corpus spongiosum 
urethrae. 
The spongy body extends the whole length of the penis, 
and where it extends backwards into the perineum, betwixt 
the crura of the penis, it is enlarged into a round head, which 
is called the bulbous part;—it is upon this, and on about an 
inch and a half of the lower part of the spongy body, that the 
ejaculator serninis or accelerator urinag acts; and,as within this 
enlargement of the spongy body which surrounds the urethras 
there is also a dilatation of the tube of the urethra itself, the 
use of the muscle is evident. It contracts upon this sinus of 
the urethra when distended with the discharge of the vesi- 
culae, the prostate gland, and testicle. 
Foreward at the extremity of the penis the spongy body is 
enlarged into the glans : thus forming the bulbous head of the 
penis which crowns the conical extremities of the cavernous 
body. 
The spongy substance which we have described, admitting 
the blood freely into its cells, suffers erection at the same time 
with the body of the penis; and as the blood of the glans has 
free connection with the blood of the bulb seated in the ure- 
thra, we may perceive that the action of the ejaculator semi- 
nis upon the back part of the spongy body must affect the 
whole extent of that body and the glans also. The excite- 
ment of the glans gives the action to the accelerator or eja- 
culator muscle ; the action of this muscle compresses the bulb, 
and in consequence the whole spongy body to the extremity 
of the glans is made turgid, and compresses the diameter 
of the urethra, adapting it to the emission of semen. Sir 
Everard Home, I observe, supposes “ that an action takes 
place in the membrane of the urethra during copulation, to 
reduce the size of the canal, and fit it for throwing out the 
semen with the necessary velocity I imagine, the action 
of the accelerator, and the state of distention of the spongy 
body, will have this effect. 
The obtuse glans spread upon the extremities of the cavern- 
ous bodies of the penis, has no communication Avith them. 
We observe a posterior circular margin on the glans ; this is 
the corona glandis, and behind this there is a depression called 
the cervix. About the corona and cervix there are many lit- 
tle glandular bodies.* 
* Gian dulse odoriferse of Tyson. See Morgagni Adversar. iv. Animad. xii. 
et sequent de tuberciclis Corona perns. STRUCTURE OF THE PENIS. 
285 
The preputium is a loose prolongation of the integuments 
of the penis, which hangs over and defends the delicate and 
sensible surface of the glans. Its inner surface is continued 
from the common integuments ; this is again reflected over the 
glans. Upon the lower side and just behind the opening of 
the urethra the preputium is tied in a particular manner to the 
surface of the glans. This connection limits the motion of 
the preputium, and is called preputii. 
The whole integuments of the penis are of the same cellu- 
lar structure with those of the rest of the body ; they are par- 
ticularly loose and distensible, and unincumbered with fat. 
We may see them in emphysema and in oedema monstrously 
distended. 
OE THE URETHRA. 
The urethra is all that length of the canal from the neck of 
the bladder to the extremity of the penis. It is formed of the 
continuation of the inner and third coat of the bladder, which 
last forms a reticular membrane, uniting the inner membrane 
to the spongy body. It is, however, supported through all its 
length, near the bladder, by passing through the prostate gland 
and sphincter fibres ; further forward than this, where it passes 
from the prostate to the beginning of the spongy body of the 
urethra, it is invested and supported by firm ligamentous mem- 
branes and muscles ; and in all the length of the penis it is in- 
cluded in the spongy body, which extends from the bulb to 
the glans. It cannot be described as a cylindrical canal, for 
it is closed unless distended with urine, and admits of very un- 
equal distention. It begins large at the neck of the bladder ; 
where, immersed in the prostate gland, it forms a little sinus; 
it is contracted again, in a remarkable degree, behind the bulb ; 
it dilates in the sinus of the urethra within the bulbous 
enlargement of the spongy body ; it is gradually diminished 
forward ; and it may be considered as cylindrical or equal in 
its diameter from this part forward to the point of the glans, 
where it is much contracted.* 
The canal of the urethra is bedewed with mucus. The 
sources of this mucus are here particularly apparent; for, be- 
sides the general surface and the glans which I have des- 
cribed, there are large lacunae observable ; into which mucus 
is secreted, and from which, as from receptacles, it is pressed 
* Haller Com. lib. xxvii. sect. I. § xxx. Mr. Home’s Strictures, Observ. de 
partibus genitalibus sexuspotioris Sandif. Thes. viii. p. 71. 286 
STRUCTURE OE THE PENIS. 
out as the urine flows.* The inner membrane of the urethra 
is very delicate, and when torn by the catheter, or by violent 
chordee, or opened by the caustic, bleeds profusely. 
The internal membranes of the bladder and urethra are par- 
ticularly sensible; drawing after them, when excited, not only 
the action of all the muscles in the lower part of the pelvis, 
but having sympathies in a particular manner with the testicle, 
stomach, and bowels, and with the whole system. The more 
curious and important effect of the injury of the urethra is the 
paroxysm of fever which it induces. Observing the regular 
occurrence of an intermitting fever in cases of fistula in the 
perineum, we should imagine it to be the effect of the extra- 
vasation of the urine in the cellular membrane, and the effect 
of general irritation ; until it is observed that the simple stric- 
ture produces that effect, and that a touch of the caustic brings 
on a violent paroxysm. 
When the reticular membrane is inflamed, of course it loses 
its elasticity and gives pain in the erection. Sometimes the 
inflammation, being continued to the spongy body surrounding 
the urethra, makes it unequal in its capacity of distention to 
the cavernous bodies of the penis, and sometimes their cells 
are united by adhesion in the worst cases of the chordee. 
i cannot imagine with some, that the urethra is muscular ; 
first, because I see no end it could serve in the economy ; se- 
condly, because there is no proof in support of the opinion ; 
thirdly, because it is surrounded with strong fibres and a spon- 
gy body, which conjointly seem calculated for every purpose 
of the economy, and likely to account for every symptom 
which might be mistaken for spasmodic action in the canal 
itself. The idea of muscularity is derived from the symptoms 
of stricture and the irritability of the canal.f 
The urethra is very elastic ; not only allowing a very large 
bougie to be passed, and closing upon a thread, but it still 
more remarkably admits of elongation than of distention in the 
* These are the Canaliculi Morgagni, Advers. Anat.—De glandulis urethrse 
vide Morgagni Adversar. iv. An. vii. et sequent. There is much controversy 
and much confusion regarding the gland of the urethra, viz. Prostate minores; 
glandule Co-vpenanx; glandule Littreanx, &.c. The reason of which I believe 
to be, that the lacunx do not appear glandular unless when they have suffered 
by inflammation; there is no round smooth body attaches to them, unless their 
secretions have been increased and the cellular membrane and vessel are con- 
densed around the lacuna:. 
f Morgagni describes the membrane of the urethra as double, having vessels 
betwixt its lamina:. These are the veins described by Dr. Hard ay. Observ. 
Anat. p. i. tab. iv. J. C. Brims, Sand. T’hes. viii. describes two laminae, one 
of which he considers to be the continuation of the muscular coat of the 
bladder. STRUCTURE OF THE PENIS. 
287 
width of the canal. It is surrounded, as we have seen, with a 
spongy body and the cellular coat which is betwixt the deli- 
cate lining membrane of the urethra, and the spongy body 
partakes of the structure of both, and is very elastic. But 
when an inflammation attacks the canal, this cellular mem- 
brane is its principal seat. The point affected loses its elas- 
ticity; no longer stretches with the penis and urethra, but 
consolidates, or forms a strong membranous filament. To 
suppose this stricture to have been formed by the muscular 
contraction in the diameter of the canal, would be to allow the 
partial action of one or two fibres; (for the stricture is very 
that which would be produced by the tying of a packthread 
round the canal, being a narrow circular ridge;) which is very 
unlikely. Sometimes, however, the stricture is only on one 
side of the canal, which, allowing u to be formed by inflam- 
mation, is very likely to happen: but in consequence of the 
muscular action, cannot easily be supposed to take place, since 
the drawing of the muscular fibres would equally affect the 
whole circle. 
As to the effect of heat and cold on an obstruction, it may 
be explained simply, without the supposition of muscular con- 
traction ; for as we know that the spongy bodies, and of course 
the whole canal, relax and elongate in warmth, as they are 
shrunk up and contracted in cold, like the skin of the body 
in general, without implying muscular contraction: so we see 
how this state would affect a stricture ;—that, when the penis 
and the urethra were shrunk, the effect of the .stricture would 
be increased, and the patient could pass his urine only when 
the parts were relaxed, by sitting in a warm room, or by the 
use of the bath. 
But when surgeons speak of spasms of the urethra, they 
seem to forget the action of the surrounding muscles. Thus 
acrid and stimulating urine, or an irritable state of the ure- 
thra, will be followed by a small stream of urine: or perhaps 
a temporary obstruction is the consequence: but why should 
we suppose that the membrane of the urethra, which has no 
appearance of muscularity, causes this effect, when it is pro- 
bably produced by the sphincter muscles, the fibres which sur- 
round the membranous part of the urethra, the levator ani, 
and, above all, by the accelerator urinas, a muscular sheath of 
fibres surrounding three or four inches of the canal. Round 
the sinus of the urethra and the bulb which covers it, is the 
accelerator urinas, more properly the ejaculator seminis. In 
short, here are a whole class of muscles which sympathize 
with the state of the urethra; and these muscles, disordered 288 
of the testes. 
in their action when the canal is inflamed, give occasion to 
those contractions which are attributed to the membrane of 
the urethra itself. 
SECTION II. 
OF THE TESTES. 
The testicle might he considered as more naturally com 
nected with the abdominal viscera, than with those of the pel- 
vis, as it? original seat is on the loins amongst the abdominal 
viscera, and as it receives its coats from the peritoneum, its 
vessels from the abdominal vessels, and its nerves from the 
plexus belonging to the vital parts. 
The testicles are two glandular bodies which secrete the 
semen: they are seated in the scrotum, and are covered and 
protected by several coats ; they receive their vessels from 
the aorta and cava, or the emulgent vessels: their excretory 
ducts run up into the belly, and terminate in the urethra near 
the neck of the bladder. 
The scrotum, in which the testicles are lodged, is a con- 
tinuation of the common integuments; its cellular membrane 
is particularly lax and free from fat, and the water of anasarca 
is extremely apt to fall down into it, so as sometimes to dis- 
tend the scrotum to a transparent bag of enormous size; and 
not unfrequently the cellular texture here has been blown up 
to counterfeit rupture and other diseases. 
Of the dartos.—Th^cellular substance of the scrotum is 
peculiar in its- appearance, being red and fibrous. It has been 
considered as amuscle, and called dartos;* although this is 
denied by many. Its action is to support and brace the scro- 
tum; and in bad health,f and in old age, it is so much relaxed 
as to allow the testicles to hang upon the cords. But besides 
the simple corrugation and relaxation, the scrotum has a mo- 
tion like the vermicular motion of the intestines, obliquely 
and irregularly from side to side. Its contraction has a rela- 
tion to the healthy secretion of the gland wdthin, and when 
lor some obstinate disease of the body of the testicle blisters 
are applied to the scrotum, we may see this muscle in great 
activity rolling round the testicles. The straight fibres of the 
* Adfjtos Yeterum. 
f Nurses attend to the state of the scrotum in children. OF THE TESTES. 
289 
Cremaster muscle could not, I imagine, perform this revolving 
motion, and therefore I conclude that the dartos is a muscle 
on a testimony better than is to be had from dissection. 
There may be traced from the web of cellular membrane 
which covers the abdominal muscle, a kind of imperfect ex- 
pansion descending upon the testicles. This becomes very 
strong when hernia has taken place at the ring.* 
Septum. Upon the surface of the scrotum, directly in the 
middle, there is a line passing from the lower part of the penis 
to the anus ; the rapha. This line marks a division in the 
scrotum, a partition, septum, which divides the scrotum 
into two distinct cellular beds for the testicles. 
Coats of the testicle. Over the proper coats of the 
testicle the cremaster muscle is expanded. The origin of this 
muscle (as we have seen in vol. i.) is from the internal oblique 
muscle of the abdomen. It passes through the hole of the ex- 
ternal oblique muscle called the ring and descends over the 
vessels to the testicle, constituting a part of the cord and finally 
spreading its fibres over the tunica vaginalis testis. Its use is to 
suspend and draw up the body of the testicle. 
Under the fibres of the muscle we may discover a process 
of cellular membrane which comes down from the cellular 
membrane behind the peritoneum, and has been usually called 
a process of the peritoneum, even before the coats of the tes- 
ticle were discovered to be originally formed by that mem’ 
brane. 
Besides the involving scrotum, each testicle has distinct 
coats. The tunica vaginalis, according to our best authors, 
covers the testicle loosely ; that is, without adhering to its ge- 
neral surface: but the albuginea is in close union with it, and 
is the immediate coat of the testicle. The inner surface of 
the vaginal coat is perfectly smooth, and an exudation is pour- 
ed out from it, as from the peritoneum within the belly. The 
outer surface of the tunica albuginea is also smooth and firm, 
and white, whence its name ; but on its inner surface, like the 
peritoneum, which covers the intestine, and adheres to the 
muscular coat, it adheres to the proper substance of the testi- 
cle. These investing coats are in some respects dissimilar, yet 
in general much alike, one being continued into the other, and 
both prolongations of the peritoneum. The outer membrane, 
the tunica vaginalis, is a protection to the testicle, gliding easily 
on the inner coat, and aided by the mobility of the cellular 
* Mauchart de hern. p. 14 tab. 2. Garengeot Haller. Monro.—I have during' 
operation divided this into three lamina. 290 
or THE TESTES. 
membrane of the dartos, it preserves the testicles from bruises 
and strokes to which it would be exposed if it were more firmly 
attached. The inner tunic or albuginea, gives strength and 
firmness to the substance of the testicle. Betwixt these coats 
is the fluid collected, which forms the hydrocele. They also 
contain the congenital hernia ; but the common hernia is with- 
out both coats of the testicle. To understand the anatomy 
of this part thoroughly we must attend to the descent of the 
testicle, and to the manner in which these coats are formed. 
OF THE DESCENT OF THE TESTICLE,* 
In the foetus, some months before birth, the testicles are 
lodged in the belly, and are in every respect like the abdomi- 
nal viscera. They are seated on the forepart of the psoae 
muscles by the side of the rectum. They are covered and 
invested by the peritoneum ; for, as we have explained how 
the solid viscera and the intestines are behind the peritoneum, 
so it will be understood how the testicles lying on the loins 
are behind the peritoneum: that is to say, the glandular sub- 
stance of the testicle is invested by a coat, and that coat is the 
peritoneum, which, after covering the body of the testicle, is 
reflected upon the loins ; as the coats of the liver, for example, 
are to be traced from its surface to the diaphragm. No words 
however can well explain this subject, and it will be better 
understood by these plans. 
* The descent of the testicle was discovered, and the formation of the coats 
of the testicle explained, by Mr. John Hunter. See Animal Economy. In 
reading Kerckringius one is apt to believe he understood the nature of the 
descent of the testicle. Specilegium Anatomicum. p. 35. OF THE TESTES. 
291 
'first plan of the Testicle. 
We see that the body of the testicle A is seated on the loins, 
that it is attached by vessels and invested by the peritoneum. 
This surrounding of the body of the testicle by the perito- 
neum forms that coat which is in union with its substance, and 
which descends with it into the scrotum, and forms the tunica 
albuginea. 
The figure and presenting surfaces of the testicle, while 
within the belly, are the same which we find after it has de- 
scended into the scrotum. It stands edgeways forward, and 
the epididymis lies along the outside of the posterior edge of 
the testes. We see that it is attached, by the peritoneum be- 
ing reflected off from its back part, and we can trace the peri- 
toneum upwards over the kidney G, and downward over the 
rectum F, and bladder of urine E. 
We may also observe a process of the peritoneum which 
has passed through the abdominal ring, and which in this plan 
is marked D. Now it may easily be understood that the testi- 
cle A, gradually shifting its place from its connections in the 
loins, drops down into this sheath D. It will also be easily un- 
derstood how the testicle, covered with its first coat B, (viz. 
the tunica albuginea,) when it has fallen into D, is invested by 
this sac of the peritoneum, and that this last covering will 292 
OF THE TESTES. 
come lo be the tunica vaginalis. The tunica vaginalis is so 
called because it covers the testicle like a sheath ; that is, it 
does not universally adhere to the surface of the albuginea, as 
that coat does to the body of the testicle. 
Understanding the nature of the peritoneum, we may learn 
the meaning of this looseness of the outer coat of the testicle. 
By turning to the introductory section of the abdominal mus- 
cles, we find that the inside of the sac of the peritoneum is 
smooth, and forms no adhesion; whilst the outer surface, being 
in contact with the substance of the several viscera, has a con- 
nection with them by a common cellular membrane. Now, 
as the inside of the peritoneum does not adhere, as the surface 
of the peritoneum (which in this first plan is towards C,) is 
smooth, and has no tendency to unite with the surface of the 
viscera; so neither has the surface of the peritoneum at D, the 
tendency to unite with the peritoneum (or the surface of the 
albuginea) at B, when it descends to meet it; consequently 
the coat of the intestines may be represented in this second 
plan, thus: 
Second and Third Plans of the Testicle. 
2d. Plan of the Testicle. 
3d. Plan of the Testicle. OF THE TESTES. 
293 
In the first plan we had the situation of the testicle in the 
foetus represented. In the second plan, we have the middle 
stage of the descent represented: and, in the third, v/e have 
the full descent. In the second figure, A is the body of the 
testicle, B is the first peritoneal covering or tunica albuginea, 
which can be easily traced, reflected off from the loins at C ; 
again, D is the portion of the peritoneum, which having de- 
scended before the testicle, is presently, when the testicle has 
fully descended, to become the second, or vaginal coat of 
the testicle ; F is the continuation of the peritoneum upon the 
inside of the abdominal muscles. 
In the third figure of this series, we find the testicle A has 
descended into the scrotum ; that it has one coat covering it, 
which we recognise to be the same with B, in the first figure, 
and that the peritoneum in this third plate at B, can be traced 
to C, the peritoneum within the belly. 
Now supposing this to be the state of the testicle immedi- 
ately after it has descended, we see that there is still a commu- 
nication betwixt the cavity of the tunica vaginalis D, and the 
cavity of the peritoneum E. F, is the kidney covered by the 
peritoneum, and nearly in the situation in which the testicle 
was before its descent. 
Fourth Plan of the Testicle. 294 
©E THE TESTES. 
From this fourth plan of the testicle, we may learn the na- 
ture of the congenital hernia. It is a hernia produced by the 
intestine slipping down from the communication betwixt the 
general cavity of the peritoneum, and the cavity of the tunica 
vaginalis, or in consequence of an adhesion betwixt the testicle 
and a portion of the gut, which of course causes the gut to fol- 
low the testicle, and prevents the communication betwixt the 
belly and the cavity of the tunica vaginalis from being shut. 
Thus fig. 4. A, is the testicle as seen in plan 3d. B, the tunica 
albuginea ; C, the peritoneum within the belly ; D, the tunica 
vaginalis, which we can trace from C, and which is distended 
and separated from the surface of the testicle, (?. e. of the al- 
buginea,) by a portion of the gut, which has descended through 
the ring: E, the point of reflection: F,the intestines within 
the belly: G, the intestine which has fallen into the tunica va- 
ginalis, and is in contact with the testicle ; that is, in contact 
with the tunica vaginalis, which is in close union with the gland, 
and is considered as its surface. 
We have explained the change which takes place in the 
situation of the testicle, as it relates to the peritoneum; but 
how this change is brought about, it is very difficult to under- 
stand. It is not a sudden pulling down of the testicle, but a 
very gradual process, continuing for months ; it is not the ef- 
fect of gravitation, for the foetus may be in every variety of 
posture while in the womb, and generally the head presents. 
It is not respiration. Is it then the effect of the action of the 
cremaster muscle ? or must we refer it to a law such as that 
which controls and directs the growth of parts ? 
When the parts in a foetus before the descent of the testicle 
are dissected, there is found a ligamentous, or cellular cord, 
mingled with the fibres of the cremaster muscle, and which 
takes its origin from the groin, is reflected into the abdominal 
ring, and stretches up to the body of the testicle. This body 
is called ligament or gubernaculum, and to the agency of this 
bundle of fibres, is the descent of the testicle attributed. There 
are, however, objections to this. If we suppose that the cre- 
master muscle, by its exertion, brings down the testicle to the 
ring, how does it pass the ring ? for surely we cannot suppose 
that this muscle, which takes its origin from the internal oblique 
muscle, consequently within, can contract, not only so as to 
bring the testicle to the very point of its origin, but to protrude 
it past that point, and through the tendon of the external ob- 
lique muscle. Again, animals have the cremaster muscle, 
whose testicles never descend out of the belly ;—again, the 
vessels of the cord, before the testicle has fully descended, oy THE TESTES. 
295 
show no marks of being dragged down, for they are elegantly 
tortuous. 
As the testicle passes very slowly from the loins to the ring ; 
so, after it has escaped from the belly it passes slowly from 
the ring to the bottom of the scrotum. It commonly remains 
Some time by the side of the penis, and only by degrees de- 
scends to the bottom of the scrotum.* 
In this change the testicles do not fall loose into the elonga- 
tion of the peritoneum like a piece of gut or omentum in a 
rupture ;—but carrying the peritoneum with them, they con- 
tinue to adhere to the parts behind them, as they did to the 
psoas muscle while in the loins ; a point; of importance to be 
recollected. 
The communication betwixt the belly and the sac of the 
vaginalis is very soon obliterated by the adhesion of the upper 
part, and then the whole extent of the passage (viz. from E to 
D, in plan third of this series,) is shut. When this process is 
pi-evented in the first instance, and nature is baulked in the hu- 
mour of doing her work, as Mr. Hunter observes, she cannot 
so easily do it afterwards. 
It has also occurred that, this communication remaining af- 
ter birth, a hydrocele has been produced, owing to the disten- 
tion of the tunica vaginalis, by fluids descending from the 
belly. The character of such a tumour will be, that the fluid 
will be easily forced into the belly. It may be mistaken for a 
congenital hernia. 
It will already be understood, that in the common hernia of 
the groin or scrotum, the gut does not pass by the communica- 
tion from the belly into the vaginal coat; that such communi- 
cation no longer exists, and that when there is a rupture from 
preternatural wideness of the abdominal ring, or in conse- 
quence of a great violence, a new portion of the peritoneum 
decends with the gut before the cord of the testicle. 
* Mr. Hunter has shown, that the detention of the testicle in the belly is in 
consequence of some defect and want of action in the testicle, and that those 
who have the testicle remaining in the belly have it imperfect or small. This 
is contrary to an old authority:—The testicles are seated externally, “ for 
“ chastity’s sake, for such live wights as have their stones hid within their 
•'* body are very lecherous,, do often cottple and get many young ones.” 296 
OF THE TESTES. 
Fifth Plan of the Testicle. 
Hernia. 
This fifth plan will now illustrate the relation of the testicle 
to the herniary sac in the common scrotal hernia. A, the 
scrotum : B, the testicle ; which will be easily understood to 
preserve its attachment to the back part of the scrotum : C, 
the tunica vaginalis, which here invests the testicle, but which 
is not now (in the adult or perfect state of the coats of the tes- 
ticle,) as is seen in plan 3d, open from D toE, but forms a short 
sac, surrounding the tunica albuginea : D, the cellular mem- 
brane of the cord of vessels passing down to the testicle. And 
now there are no remains ot the tube of communication be- 
twixt the belly and vaginal cavity ; it is obliterated and resolv- 
ed into this cellular membrane. 
We see, then, that in this plan the testicle and its coats, and 
the spermatic cord, are in their natural situation, and that the 
herniary sac has descended before them. E, is the ring of the 
external oblique muscle of the abdomen, through which not 
only the testicle, with its coats and vessels, has descended, but 
also the hernia : F. the herniary sac, which contains a portion 
of the gut; it is formed of the peritoneum, fallen down from 
the belly, but it is quite distinct from the sac of the tunica va- 
ginalis C. Whilst this new process of the abdominal perito- OF THE TESTES. 
297 
neum has descended, it has contracted adhesions, and cannot 
now be replaced. 
In thus explaining these important principles of anatomy, 
and which the anatomical student will find wonderfully to fa- 
cilitate the more minute study of surgical anatomy, it only re- 
mains to show the nature of the hydrocele. 
The hydrocele is a collection of water within the sac of the 
tunica vaginalis ; that is, betwixt the tunica vaginalis and tu» 
nica albuginea. For, as we have seen, that the same surface 
of the vaginal coat is contiguous to the surface of the testicle 
(viz. the albuginea,) with that of the peritoneum, which is 
contiguous to the viscera of the belly ; and as it has the same 
exudation, so it has the same disease, viz. a collection of wa- 
ter, from the absorption being disproportionate to the exuda- 
tion. When the tunica vaginalis is distended with the water 
of a hydrocele, the testicle is towards the back part of the 
scrotum ; it can be felt there ; and when the scrotum is placed 
betwixt the candle and the eye, we see the transparent sac 
on the forepart of the tumour, the opaque mass of the tes- 
ticle behind ; generally the distended vaginal coat stretches up 
before the cord conically : thus : 
Sixth Plan of the Testicle. 
Hydrocele. 298 
«F Tint TESTES. 
A, the penis; it is generally corrugated thus, in consequence 
of the distention of the scrotum in scrotal hernia and hydro- 
cele : B, the scrotum : C, the testicle, covered only by the tu- 
nica albuginea : D, the cellular membrane of the cord : E, the 
tunica vaginalis, distended with the water of hydrocele, and 
consequently separated from the surface of the testicle : F, 
that part of the sac of the vaginal coat, which often extends 
conically before the cellular membrane of the cord D. Now 
we see that the distention of the vaginal coat does not open 
up the old communication with the belly ; but that the former 
communication being shut, and the peritoneum there degene- 
rated into the cellular membrane of the cord, the hydrocele is 
a distinct sac, surrounding the testicle, and formed of the tu- 
nica vaginalis. 
To understand this subject of the coats of the testicle, it 
is not necessary merely to consider the descent of the testicle; 
but the student must consider it in every point of view, turn 
it as it were into every variety of posture, without which his 
difficulties will perpetually return upon him. It is for this rea- 
son that I have endeavoured to represent the various states 
of the coats of the testicle in disease. 
, I have here used the terms tunica vaginalis, and tunica al- 
buginea, as my reader will find them interpreted in our best 
old authors. But we may now inquire a little farther. 
When we dissect the coats of the adult testicle, we can fol- 
low the tunica vaginalis over the surface of the testicle, and 
by dissecting, separate it from the testicle, leaving that body 
covered by a dense membrane. Specimens may be seen in my 
Collection, where hydatids, forming betwixt these membranes, 
have separated them in a manner still more satisfactory than 
can be done by dissection. What terms are we to use for 
these three membranes? 1. tunica vaginalis; 2. tunica vagi- 
nalis refexa; and, 3. tunica propria testis.* 
OF THE VESSELS OF THE CORD AND TESTICLE. 
In attending to the descent of the testicle, we have a clue 
also to the vascular system. If we did not know that the tes- 
ticles were originally placed in the loins within the belly, we' 
might wonder at the length and origin of the spermatic ves- 
sels. 
* De Graaff speaks of the division of the tunica albuginea into two mem- 
branes, probably meaning to distinguish the cellular tissue of the body of the 
testicle from the investing membrane. Morgagni in his commentary on him 
tells us he can separate the tunica albuginea into two lamiha, the inner of 
which was the most delicate. Advers. An. iv. Animad. i. » The spermatic artery rises on one side from the forepart 
of the aorta, below the emulgent artery, and on the other 
from the emulgent artery, sometimes they arise from the ar- 
teries of the renal capsule: sometimes there are two sper- 
matic arteries to one testicle. This artery, which the cord 
receives from the aorta or emulgent, is called the superior 
spermatic artery, because there is another which rises from 
the hypogastric artery ; this branch runs upward, connected 
to the vas deferens, as it rises out of the pelvis. Another 
artery is given to the membranes of the testicle from the 
epigastric artery. 
These arteries, taking their course under the peritoneum, 
join the fasciculus forming the cord, and supply the cord, and 
send twigs to the investing peritoneum; they then pass through 
the abdominal ring, and in their course they are beautifully 
tortuous. 
The veins of the testicle terminate on the right side of the 
trunk of the cava, a little below the emulgent vein, and in the 
emulgent vein on the left side. There is also (accompanying 
the vas deferens) a vein, which joins the internal iliac vein. 
All these veins, in their course from the testicle, are pro- 
tected from the column of blood, and from the consequences 
of compression, by numerous valves. These valves are very 
strong, and will bear a great column of mercury before they 
give way or burst. This plexus of convoluted veins of the 
cord is the most beautiful in the body; and we may observe, 
that such convolutions of veins are ever attendant on arteries 
tortuous in their course, and subject to occasional excitement. 
And further, if by accident there is excited an uncommon ac- 
tion in the arteries of a living body, that action will be appa- 
rent from the distended or enlarged state of the veins. In 
the testicles of such animals as have their seasons, the artery 
and veins of the testicle become still more convoluted, and 
form a mass of vessels, which has been called corpus pyramid 
dale* 
The nerves of the testicle, like the blood-vessels, come 
from the loins ; they form a division from the emulgent plexus 
and are continued down upon the vessels. This connects the 
testicles to the abdominal viscera, giving them much of the 
same sympathies. The stomach, intestines, and testicle, sym- 
pathize readily with each other. 
OF THE TESTES. 
299 
* Corpus varicosum,—Corpus Pampiniforme ; Galen de Semine. Alias pa- 
rastatam varicosam, Hall.—As the old physiologists saw and observed this 
wonderful tortuosity, and the tendril-like form of the spermatic artery, they 
thought that the blood was here begun to be changed into semen, and there- 
fore they called them the vasapreparcintia. 300 
of the testes. 
The lymphatics of the testicle are numerous, and easih 
demonstrated by blowing up the cellular structure, of the body 
of the testicle; and this has been the ground of dispute be- 
tween physiologists ; and the proofs of some important points 
in the doctrine of absorption have been drawn from the injec- 
tion of the lymphatics of the testicle and cord. 
The cremaster muscle, as we have seen in the first 
volume, takes its origin from the internal oblique muscle of 
the abdomen, from the os pubis, and passing down over the 
vessels of the cord, is expanded on the tunica vaginalis. The 
use ascribed to it is to suspend the testicle, and prevent it 
from dragging upon the vessels of the cord; but I conceive 
it chiefly useful in compressing the body of the testicle, draw- 
ing it up, and accelerating the discharge of semen. 
Thus we And the cord of the testicle, as it is called, to con- 
sist of the excretory duct; of the arteries, veins, and nerves -r 
of the lymphatics returning from the testicle ; of the cellular 
tissue embracing and supporting all these vessels ; and lastly,, 
of the fibres of the cremaster muscle. 
OF THE STRUCTURE OF THE TESTICLE. 
It is to De Graaff that we owe the knowledge of the 
structure of the testicle ; and indeed the merit of this great 
anatomist has not been acknowledged with sufficient gratitude 
by modern anatomists : but after the fervour of disputation 
has subsided, the merit of ingenuity and of discovery must 
return to him to whom it is due. No one more highly values 
than I do the improvements of anatomy by the Hunters and 
Monro; but I must say, that the structure of the testicle was 
demonstrated by De Graaff to his fellow anatomists of Mont- 
pelier; and his discoveries published in a manner so perfect, 
as to leave us little to learn from modern authors. • 
De Graaff, by exciting the gland of brutes, and tying the 
spermatic cord, had the seminal vessels distended. He did 
not depend upon injections ; by maceration and dissection in 
this distended state, he unravelled all the intricacies of their 
tubes. More modern anatomists have proved the truth of his 
observations by injections ol mercury, and have succeeded in 
a variety of ways of preparing the testicle. 
Tubuli testis.—When the tunica propria testis is lifted, 
the body of the testicle is found to consist of innumerable de- 
licate white tubes ; which, when disentangled from the minute 
cellular membrane which connects them, and floated in water, 
exhibit a most astonishing extent of convoluted vessels. Bv OF THE TESTES. 
301 
a closer attention, however, to this structure before it is 
thrown into confusion by pulling out the tubes, they appear to 
be regularly laid in partitions of the cellular membrane. These 
sepimenta are very regular in some animals, and while they 
separate the seminal tubes, they support and convey the 
blood-vessels to the secretion of the semen. Dr. Monro has 
denied the formal divisions which De Graaff had engraved, 
but admits them less regular, less easily found, and not so 
limited in their number; nor does he find them to prevent all 
communication betwixt the tubes of the testicle. 
These seminiferous tubes of Haller, or tubuli testis of Mon- 
ro, run towards the back of the testicle. Each of these tubes 
seems to be cylindrical, or of one diameter throughout their 
whole extent: we see no communication betwixt them ; no 
branches given out or going into them ; nor have I been able 
to distinguish a beginning for the whole, nor for any one of 
them. There seems to be only one tube wonderfully convo- 
luted and folded up in each subdivision of the testicle. 
Rete testis.—When the tubuli come out from the body 
of the testicle, they run along the back of it, and communi- 
cate by inosculations with each other, so as to form a net- 
work of vessels, from which appearance Haller named them 
rete testis. 
Here it often happens that the mercury stops when it has 
been injected backward from the vas deferens ; and it is this 
part which has been better described and drawn, in conse- 
quence of mercurial injections, than it was by De Graaff; 
lor he, as we have said, saw this part only filled with semen. 
Connected with the rete testis is the corpus Highmoria- 
num.—Where the lines of the membranous septa, and cellular 
membrane of the testicle, meet on the back of the testicle, 
and under the epididymis, they form a white line. This white 
line running along the testicle, was supposed by Highmore to 
be a hollow tube ; it was compared with the salivary duct; it 
was thought to be a cavity leading from the body of the testi- 
cle to the head of the epididymis, and to form the communica- 
tion by which the semen flowed from the testicle. De Graaff 
first refuted this notion, and showed that it was not by this one 
great duct, but by these smaller tubes forming what has been 
now called the rete testis, that the semen came from the testi- 
cle ; still it had continued a question, whether this white line 
was really solid, or a tube ; and upon faithful examination of 
the point it appears, that this is expressly as it was explained 
by De Graaff, viz. that it is a mere collection of the mem- 
branes of the body of the testicle, forming a linea alba; and 302 
OF THE TESTES. 
as the septa are more distinguishable in some animals, so is 
the corpus Highmorianum.* 
Vasa efferentia. The tubes running on the back of 
the testicle, and forming the rete testis, we have understood 
to arise from the tubuli testis ; now it is the continuation of 
the rete testis which is called vasa efferentia. The vasa effe- 
rentia are very delicate vessels which run out from the head 
of the testicle, single at first, but they are soon convoluted, 
and by these convolutions they are formed into an equal 
number of vascular cones, which constitute the head or larger 
part of the epididymis. These vasa efferentia and vascular 
cones are connected by a very delicate cellular membrane; 
and it is a piece of very nice dissection to display them after 
they are injected with mercury. 
Epididymis.—The vasa efferentia, after forming three coni- 
cal convolutions, unite and form larger tubes ; these again 
uniting, and form one large excretory duct, the vas deferens ; 
but this vessel, being convoluted to a wonderful degree, forms 
a body, which being as it were placed upon the testicle, has 
been called epididymis. 
Seventh Plan of the Testicle. 
In this representation of the dissected testicle, A is the body 
of the testicle divested of its coats ; B, the tubuli testis ;f CC, 
the rete testis ; D, the vasa efferentia ; E, the vascular cones ; 
F. the epididymis, formed of the convolutions of the vas 
deierens; lastly, G is the vas deferens. 
*■ I body is called a mere firmamentum or binding'.—Winslow, 
f Where the tubuli are emerging to form the rete vasculosum they are callec 
the vasa recta. OF THE TESTES. 
303 
In the substance of the testicle there are no glands nor folli- 
eules; the arteries minutely ramify amongst the seminal tuhes, 
and, there is reason to believe, secrete the semen into them. 
The seminal vessels in the substance of the testicle, or tubuli. 
testes, run together upon the surface of the testicle, and form 
the rete testis. From the rete testis are continued the vascu- 
lar cones : these convolute, and running together form the 
epididymis ; from which the tube is continued under the name 
of the vas deferens. It passes up the cord, enters by the 
ring into the abdomen, and then, passing down into the pelvis, 
terminates in the vesicuke seminales, in a manner presently to 
be explained. It is not likely that the vis a tergo, the power 
of the arteries, pushes the semen through all this length of 
tube, of which the epididymis itself is reckoned to be several 
feet in length, if the various convolutions were undone ; such 
an action on the testicle as that of the dartos or cremaster 
muscle, could give only a general pressure, but could not force 
on the semen in tubes which take so great a variety of direc- 
tions. We are therefore left to the supposition, that these 
tubes themselves have apower of accelerating the fluids through 
them. 
There is a duct which sometmes arises from the epididymis, 
and which we find to terminate abruptly in a blind end—of 
this, Mr. Hunter speaks in the.annexed note.* 
The testicle is of an oval form, and of the size of a pigeon’s 
egg ; it is a little flattened on the sides: it hangs in the scro- 
tum by the spermatic cord ; one end of the oval, forward and 
high ; see plan 8th, B ; while the other is backwards, and drops 
OF THE TESTICLE IN GENERAL. 
* “ By a supernumerary vas deferens, [mean a small duct, which sometimes 
arises from the epididymis, and passes up the spermatic cord along with the 
va3 deferens, and commonly terminates in a blind end, near to which it is some- 
times a little enlarged. I never found this duct go on to the urethra, but in 
some instances, have seen it accompany the vas deferens as far as the brim of 
the pelvis. There is no absolute proof that it is a supernumerary vas deferens; 
but as we find the ducts of glands in general very subject to singularities, and 
that there are frequently supernumerary ducts, there being often two ureters 
to one kidney, sometimes distinct from beginning to end, at other times both 
arising from one pelvis ; these ducts arising from the epididymis, I am inclined 
to believe from analogy, are of a nature similar to the double ureters. They 
resemble the vas deferens, as being continuations of some of the tubes of the 
epididymis, are convoluted where they come off from it, and afterwards be- 
come a straight canal passing along with it for some way, when they are com- 
monly obliterated. 
“ The idea of their being for the purpose of returning the superfluous semen 
to the circulation is certainly erroneous, from their being so seldom met with, 
and so very seldom continued further than the brim of the pelvis.” Many etv 
amples of this may be seen in my Collection. 304 
OF THE TESTES. 
lower, C. The spermatic cord consists of the artery which 
brings blood; of the veins which return it; of the vas deferens, 
which carries the semen to the vesiculse seminales at the neck 
of the bladder; of lymphatics, which are essential to the 
structure of every part. This cord of vessels comes down from 
the belly, and passes by the ring of the abdominal muscles : it 
is about four inches in length, and is fixed into the upper and 
forepart of the body of the testicle. 
The body of the testicle is easily distinguished, and is the 
place where the secretion is performed. It is strictly the 
body of the gland, while the part above it is only the duct by 
which its fluid is discharged- 
The ancients called the testicle dydimi, gemini, twins; they, 
therefore, called that part which is laid on the back of the 
testicle epididymis, as added to it. To the surgeon, it is essen- 
tially necessary to attend to the relation of the parts of the tes- 
ticle as felt through the scrotum. 
Eighth Plan of the Testicles. 
Fy.l 
&g.2. 
In this 8th plan, fig. 1. we see the testicle as in its natural 
situation, covered with its membranes, and appearing like one 
body; while, in the second figure, it being represented freed 
from its outer coat, we see the epididymis as laid upon the 
testicle, and consisting of the convoluted tube. First, we ob- 
serve A, the body of the testicle: B, the beginning of the 
epididymis, or the large head of the epididymis :* then we see 
it laid along the back of the testicle, and observe C to be the 
* Globus major, or head. OF THE TESTES. 
305 
small head of the epididymis,* whefe tire tube is reflected to 
reascend upon the testicle, and to form D, the vas deferens. 
Now, we have to observe, that the point C, fig. 2. or small 
head of the epididymis, hangs over the testicle, and points back- 
wards to the perineum, and can be felt through the whole 
coats : and that the body of the testicle A, is towards us when 
we examine a patient.—Further, as the letters in figure l. and 
2. refer to the same points, we have only to notice the fainter 
indicatibn of the parts in fig. 1. it being invested with the coats, 
and to observe the general relation of the testicle to the scro- 
tum and penis. 
There is one other circumstance to be observed, viz. that 
the epididymis is always laid on the outer side of the insertion 
of the cord into the testicle ; from which we distinguish, with 
ease, in a preparation, to which side the testicle belongs. Thus, 
in the annexed plans, the testicle of the left side is represented, 
which we know from the points C, being directed backward, 
while the epididymis is laid along the left side of the insertion 
of the cord. 
OF THE VES1CULJE SEM1NALES 
Behind the prostate gland, and attached to the lowest part 
of the urinary bladder, lie two soft bodies, the vesiculae semi- 
nales. They appear like simple bags when seen from with- 
out, but dissections show them to consist of cellular struc- 
ture : each of these bodies is about three fingers-breadth in 
length ; their backmost point is large and round, and, at the 
same time that they diverge from each other, their narrow 
points unite, or are contiguous to each other forwards, and en- 
ter at the back part of the base of the prostate gland. 
As we have seen, the peritoneum does not descend far 
enough betwixt the bladder and the rectum to cover or invest 
these vesiculse: they are therefore involved in the cellular 
texture, and covered with strong fibres, besides being subject 
to the compression of the levator ani muscle. When the ve- 
siculae are cut into, and especially when they are distended, 
dried, and cut, they appear cellular ; but if they are carefully 
dissected, they present the appearance of a convoluted duct. 
This cellular appearance is given by the duplication of their 
inner membrane, together with the distortions and curves of 
* Globus minor.—This part we often distinguish retaining its hardness after 
the subsiding of the general swelling of hernia humoralis. From this point 
we can trace all the connections of the other parts. OF THE TESTES. 
306 
the canal. Their outer surface is covered with a fine mem- 
brane, which connects these cellular convolutions. 
The vesiculae are copiously supplied with arteries ; their sur- 
face is covered with veins and lymphatics. Hiester, Winslow, 
and others have described small glands seated in their sinuo- 
sities ; but these are confidently denied by others. These ve- 
siculae are themselves glands, or in other words, the arteries 
secrete into them a peculiar fluid. The forepart of each of 
the vesiculse, which we have said sinks into the back part of 
the prostate gland, runs under the neck of the bladder, and 
opens by a distinct mouth into the urethra on the surface of 
the verumontanum. 
The connection of the vas deferens with the vesiculse is very 
particular : the duct and the extremity of the vesicular tube 
join, and they together open into the urethra. There is no- 
thing in the human structure to discountenance the idea that 
the semen may pass retrograde from the vas deferens into the 
vesicular seminales, but as in some brutes the vas deferens has 
no connection with the vesiculse seminales, it is to be pre- 
sumed that they are not mere receptacles of the secretion of 
the testicles.* 
The extremity of the vas deferens joins the duct of the ve- 
siculse where it is imbedded in the prostate gland ; the union of 
the vas deferens and duct of the vesiculse is not attended with 
an enlargement of the duct; on the contrary, as the duct passes 
forward deep into the substance of the gland to arrive at the 
urethra, it becomes remarkably narrower until it opens in a 
very small orifice in the verumontanum, as we see represented 
in the third plate. The duct (if we may so call it) of the vesi- 
culae passes a full inch forward into the gland before it termi- 
nates in the urethra. 
The vesiculse appear to be useful in adding a fluid to the se- 
cretion of the testicle, which being poured together into the 
sinus of the urethra, are then sufficient to distend this part of 
the canal, by which too the ejaculator muscle is exerted and 
effect given to its action ; for a smaller portion of fluid would 
not be carried forward by its contraction, unless there were a 
provision of fluid sufficient to distend the sinus of the urethrae, 
the semen could not be thrown out from the urethra. This 
supposition is not opposed by the facts stated by Mr. Hunter, 
that in many animals the vesiculse and vasa deferentia open 
by distinct foramina into the urethra, because in that case the 
fluids of these secreting bags might be equally mingled with 
* See explanation of plate III. OF THE TESTES, 
307 
the semen in the sinus of the urethra, although they do not 
■flow from the same tube. 
Verumontanum.—The verumontanum or caput galinagi- 
nis, is an eminence on the lower part of the urethra, where it 
is surrounded by the prostate gland. It is larger and round 
towards the bladder, and stretches with a narrow neck for- 
wards. On its summit, the two orifices of the seminal vessels 
open ; and around it there are innumerable lesser foramina 
and mucous follicules, the duct of the prostate gland. 
The sinus pocularis is the sac or large lacuna formed 
within the caput galinaginis ; its mouth is directed forwards, 
so that the urine flowing out of the bladder lays the margin 
down, the seminal orifices open within the margin, and they 
are by this means protected from the urine. Sometimes the 
ducts are found opening on the sides of the sinus. THE 
AlfJkWMlf 
OF THE 
FEMALE PARTS OF GENERATION. 
THE ANATOMY OF THE PARTS IN THE FEMALE PELVIS. 
THE parts of generation are divided into the external, 
which are those without the pelvis ; and the internal, or vis- 
cera of the pelvis, and which lie within the bony circle of the 
pelvis. 
CHAP. I. 
THE EXTERNAL PARTS OF GENERATION. 
The external parts of generation are the mons veneris, la- 
bias, clitoris, nymphae, urethra, hymen, and carunculae myrti- 
formes. Upon these subjects we have no want of books and 
information ; for accoucheurs of the old school dwelt upon the 
description with particular accuracy. These parts were within 
their ken, which we cannot say of the viscera of the pelvis; 
and therefore upon this first head we shall be more brief. 
In very young children these external parts bear a large 
proportion to the body, greater than at any subsequent period* THE EXTERNAL PARTS OF GENERATION. 
309 
before the age of puberty. At puberty they are suddenly and 
completely evolved, and acquire an increase of size ; while, 
from the age of two years to twelve or thirteen, there has been 
little increase. Preceding'menstruation is the development 
of the uterine system : the whole parts internal and external 
partake of a sudden impulse. 
The parts become turgid and vascular ; the fat is deposited 
in the surrounding cellular membrane. About the fortieth 
year, when the menses disappear, this fulness of the private 
parts also ceases, and the fat is re-absorbed. 
The mons veneris is that prominence on the symphysis 
pubis, which consists of the skin raised and cushioned up by 
the fat inclosed in the cellular membrane. There is a great 
variety in its size. In early life it is small: it becomes, as we 
have said, more prominent at the age of puberty; in fat wo- 
men it is of an enormous size; and in some warm climates a 
particular laxity prevails. From the hair on this part, mark- 
ing the age of puberty, it' is called pubes. ’ As the lax texture 
admits of distention with the fluid of anasarca, it is some- 
times from this cause very greatly swelled. 
The labii.—These are often named alse, from a slight re- 
semblance to wings, and they are also called externas, magnse, 
or majores, from their place, and from their superiority in 
respect of size over the nymphas. The labii seem to be the 
mons veneris continued downward and laterally, until meet- 
ing below, they form the vulva ; at their lower angle by their 
union they form the fourchette, or frenum labiorum. The 
structure of the labise is similar to that of the mons veneris; 
sometimes one is larger than the other. 
The great sensibility of the membrane which lines the in- 
side of the labii requires some defence, and therefore the 
whole surface is amply supplied with mucous follicules and 
glands. The labii are a protection to the other soft parts, so 
necessary, that the clitoris, or nymphse, when they project be- ( 
yond them, are subject to violent inflammation. 
The parts here have either such folds, or are of so lax a 
texture, as to permit a great degree of distention during the 
passage of the child. But as the labii have no muscular power, 
and depend entirely on their elasticity for restoring them 
to their original size, they commonly, after being very much 
dilated, remain in some degree larger and more lax. It is dif- 
ferent with muscular parts, as the orificium externum, which, 
by the power of its sphincter, is restored after labour to its ori- 
ginal size. In man, hernia descends from the abdominal ring 310 
THE EXTERNAL PARTS 9F GENERATION. 
into the scrotum : but in woman, when there is a rupture from 
the ring (which is rare) it falls into the labium. 
The nymphi are named labii vel alae minores, or labise in- 
ternae, to distinguish them from the great labise. They are like 
a miniature representation of the great labias; they are covered 
with a very delicate membrane, and have great sensibility. 
They begin immediately under the glans clitoridis, and seem 
to be only an extension of its preputium, formed by a folding 
of the membrane. Their size varies much. They commonly 
stretch downward and backward, to the middle of the ori- 
fice of the vagina; sometimes no further than to that of the ori- 
ficium urethrae, and in a few instances they extend even in the 
length of the fourchette.* They are very vascular, and have 
somewhat of a cellular structure, and thus partake of a degree 
of turgidity, in consequence of irritation and vascular action. 
The most modest of the uses ascribed to them is, that of di- 
recting the stream of urine. As they are obliterated during 
the passage of the child’s head through the vulva, it is pro- 
bable that they facilitate the necessary dilatation. 
The nymphse are, in their natural situation, covered and 
completely protected by the labii externi. When naturally 
large or increased by disease, or in a very relaxed state, they 
are deprived of this covering: they project from under the la- 
bii, and are apt to become inflamed, and even to ulcerate. 
The original disease, or tumour is augmented, or they become 
perhaps hard and callous. In children they bear a very great 
proportion to the other parts, and are more conspicuous and 
prominent than in the adult. Their diseased enlargement 
sometimes requires to be extirpated, in which operation, as 
they are very vascular, and as with their growth, their blood- 
vessels enlarge, considerable hsemorrhagy may be expected. 
The clitoris is similar to the male penis. Like the penis, 
it consists of cells for receiving blood, and in a similar man- 
ner, it arises from or takes hold of the rami of the os pubis by 
two crura; these unite at the symphysis pubis, to form the 
body of the clitoris, which is suspended from the os pubis, 
like the penis, by a kind of ligament. The clitoris has also a 
kind of glans, over which the integuments make a fold like a 
preputium. In short, it has the same sensibilities, the same 
power of erection with the membrum virile ; only it has no 
urethra nor spongy body, like that of the urethra of man. 
The stories of the increase of this, even to its pre-eminence 
in size over the male penis, are very idle, but there seems to 
be a peculiar predilection for them. It is not wonderful that 
* Both Riolin and Morgagni have seen the parts without the nymphac. THE EXTERNAL PARTS OF GENERATION. 
311 
a clitoris of such magnitude should suggest the idea of a her- 
maphrodite, or person partaking equally of the distinguishing 
attributes of either sex. 
The urethra of the female is short, straight, and wide; its 
length an inch and a half, or two inches ; its direction nearly 
straight, or only slightly bending under the os pubis ; and its 
diameter such as will admit a catheter the size of a writing 
quill. The consequences of these peculiarities are, that the 
catheter is easily passed when there is no very unusual obstruc- 
tion ; that women are not so much exposed to the disease of 
stone in the bladder as men, for though this is much owing to 
constitutional peculiarities, yet it is obvious, that where a small 
stone is formed, and passes from the bladder, it is easily dis- 
charged. If it does not pass with the flush of urine, yet the 
canal may be dilated, so that a very considerable calculus may 
be discharged without incision. 
The opening of the urethra is in a direct line under, or be- 
hind the clitoris, and about an inch from it: it is in the mid- 
dle of a straight prominence, and its vicinity is plentifully sup- 
plied with mucous glands. If the relation of the orifice to the 
clitoris be observed, there is, in the natural state of the parts, 
no difficulty in slipping the point of the catheter, on the end of 
the middle finger, from the clitoris, until it is caught upon the 
lacuna-like orifice of the urethra ; but even in this part of the 
operation, I have experienced great embarrassment, from an 
irregular ulcerated or cancerous surface of the parts, by which 
all the usual distinctions were lost. 
From the length and sudden turns of the male urethra, 
from the double function it performs, and from its being em- 
braced by the prostate gland, the obstructions of the urine are 
more frequent, and the catheter less easily passed than in wo- 
man. The catheter too requires to be of a very peculiar form. 
The short and wide urethra of woman requires only a simple 
and almost straight tube : and although accurately to adapt it 
to the course of the urethra, a considerable curve might be 
given to it, yet that is not necessary in common cases; and 
circumstances will occur to the accoucheur which will preclude 
the possibility of using such an instrument. 
We shall only mention here such cases of obstruction of 
urine as are in a particular manner illustrated by the anatomy 
and connection of the parts. These are tumours of the ova- 
riiyn, tumours of the womb, polypi, distention of the vagina. 
OF THE URETHRA. 312 
THE EXTERNAL PARTS OF GENERATION. 
displacement of the womb, as procidentia, prolapsus, retrover- 
sio, &c.; and lastly, the child’s head in labour. 
The ovarium being enlarged, and falling down into the 
pelvis, either presses upon the neck of the bladder, causing 
obstructions, or pressing and weighing on the fundus of the 
bladder, it occasions a stillicidium urinas. 
Tumours of the womb, especially of the neck or orifice, as 
it is in contact with the urethra, very soon affect this organ. 
Thus, I have seen a cancer of the orifice of the womb, by ex- 
citing inflammation in all the surrounding parts, and by mass- 
ing them together into a tumour filling the pelvis, occasion 
obstinate obstruction of urine. 
Polypi attached to the orifice of the womb, and filling the 
vagina, produce the same effect. In all such cases, perhaps, 
the tumour may be pushed up, so as to permit the flow of 
urine, or the introduction of the catheter. 
A case occurred to Mr. John Bell, in which the tumour of 
the womb compressed the neck of the bladder. A catheter 
was passed, and gave instant relief. The midwife, after some 
time, came, and said, that the catheter would not pass. He 
found that he could pass the catheter into the bladder, but no 
urine flowed ; and it was discovered, that the tumour, increas- 
ing backward, came to press upon the ureters, so as com- 
pletely to obstruct them where .they enter the bladder. The 
woman unavoidably died ; each kidney and ureter was found 
to contain four or five ounces of urine. 
A slight sketch of the parts in the female pelvis will, per- 
haps, better explain the connections of the neck of the blad- 
der than any description, and will certainly better illustrate the 
cause of some kinds of obstruction, particularly that arising 
from the change in the posture of the womb. THE EXTERNAL PARTS OF GENERATION. 
313 
First Plan of the Female Pelvis. 
A, the os pubis cut through; B, the spine and sacrum also 
cut directly down; C, the urinary bladder moderately dis- 
tended, and rising behind the pubes; D, the urethra, very 
short, and taking a gentle curve under the symphysis of the os 
pubis; E, the fundus of the womb; F,the os tineas, or orifice 
to the womb; G, the vagina; H, the rectum. 
Prolapsus, or falling down of the womb, is frequent with 
those Avhp have borne many children. By this slipping down 
of the body of the womb F, into the vagina G, it presses on 
the neck of the bladder, or urethra. This is also apt to hap- 
pen in the first months of pregnancy, from a degree of difficulty 
which the womb in its enlargement has in rising above the 
brim of the pelvis. 
We may observe also from the place of the vagina G, that 
its diseases, its scirrhous hardening, its distention by the 
menses, will also compress the urethra and neck of the bladder. 
The retroversion of the womb is the most formidable ob- 
struction to the urethra. It is produced by distention of the 
bladder acting on the womb in a particular situation, and is the 
cause of suppression of the urine. When the womb in the 
third or fourth month of gestation has increased so much as to 
produce a degree of compression on the surrounding parts, 
and to rise above the brim, and shoot up into the abdomen, a 
distention of the bladder is apt to throw the fundus under the 
projection of the sacrum. We have to observe the connection 314 
THE EXTERNAL PARTS OF GENERATION. 
betwixt the back and lower part of the vagina. By the dis- 
tention of the bladder, the vagina is stretched, and the orifice 
of the womb is raised, which throws back the fundus of the 
womb, so that this comes to be the situation of the parts. 
Second Plan of the Female Pelvis. 
A, the os pubis; B, the sacrum ; C, the bladder of urine 
much distended, and rising above the pubes ; D, the con- 
nection betwixt the back part of the bladder and the upper 
part of the vagina, and through which the rising of this part 
of the bladder (in consequence of its distention) has drawn 
up the orifice of the womb, and thrown back the fundus. E, 
the orifice of the womb, which being raised and turned up, 
no longer presents so as to be felt by the finger in the vagina. 
It will be observed also, that the womb now lying across the 
pelvis, this lower part is forced against the neck of the ure- 
thra, so as to compress it, and cause total obstruction of urine. 
F, the vagina, which is stretched in consequence of the rising 
and turning up of the orifice of the womb. G, the fundus of 
the womb enlarged and distended by impregnation, fallen THE EXTERNAL PARTS OF GENERATION. 
315 
back under the promontory of the sacrum, and compressing 
the rectum H. 
Now, when the fundus of the womb is thrust back, and the 
orifice raised by the distention and consequent rising of the 
bladder, the natural and simple cure is to introduce the ca- 
theter, and draw off the urine. But should this not be done at 
first, then there being distention of the bladder, and pressure 
on the rectum, the abdominal muscles sympathize with these 
parts, so that bearing-down efforts are made, and the fundus 
of the womb is forced further down into the hollow of the 
sacrum, while the orifice is directed upward. 
Were this distention to happen at any other time than just 
when the uterus is of such a size, that, being thrown back, it 
catches under the sacrum, and does not rise again, no harm 
could follow.—I last year attended, with Mr. Cheyne, senior, 
a woman afflicted with obstruction of urine, who died. I 
afterwards opened the body, where the womb, being enlarged 
by disease, had produced much the same effect as if it had 
been enlarged by pregnancy, viz. obstruction of the urethra; 
for the body of the womb had fallen into the hollow of the 
sacrum, and had formed adhesions there with the rectum, 
while the orifice of the womb pressed forward upon the os 
pubis, so as to produce an obstruction of the urine. The parts 
were otherwise diseased, and this was one cause of the obsti- 
nacy and fatal determination of the complaint. 
As we treat of those subjects only as connected with the 
urethra, we may observe, that sometimes the urethra takes a 
course, not round behind the os pubis simply, nor straight up- 
wards, but curved backwards, so that the convexity of the ca- 
theter requires to be towards the sacrum, to allow the point, 
to pass over the orifice of the womb, or perhaps the flexible 
or the male catheter may be required. 
The effect of the wedging of the child’s head in a tedious 
labour, is to elongate and compress the urethra in a very par- 
ticular manner. Many young men have felt the difficulty of 
introducing the catheter in this case. But it is a difficulty 
proceeding generally from ignorance or inattention. I believe 
there never occurs a case in which the child’s head is so firmly 
impacted, that the catheter cannot be passed. But often 
practitioners forget the direction which the urethra necessarily 
assumes, when the child’s head has sunk into the pelvis. 
Orificium vaginae.*—This is also named orificium ex- 
ternum, in distinction to the uterine orifice. I notice it under 
the head of the external parts, because we have to speak of 
the parts which surround the orifice, as the hymen. 
All anterior or external to the orifice of the vagina and 316 
THE EXTERNAL PARTS OF GENERATION. 
within the labii is the vestibulum. The orifice of the vagina 
of the human female is abridged by the hymen, which is a pe- 
culiar membrane. It is of a semilunar form, and sometimes 
surrounds the lower part of the orifice of the vagina ;—com- 
monly it surrounds only the lower half of the circle, though it 
would seem to vary considerably in shape, place and strength. 
It has been found surrounding the whole circle of the orifice, 
leaving only a small hole in the centre or upper part; or it is 
described as perforated with lesser holes, allowing the evacua- 
tion of the menstrual blood. In other cases, it has been found 
a complete septum, preventing the evacuation of the men- 
strual blood.—This is a fact which I do not dispute, lor I 
know that the perforation for the evacuation of the menstrual 
blood is sometimes necessary. When I have seen the imper- 
forated vaginain the child, it was not the hymen which closed 
the orifice, but an adhesion of its sides ; yet this adhesion, if it 
had come to be distended with the menstrual blood of several 
periods, would have presented the appearance of a tense mem- 
brane stretched across the orifice. 
Such semilunar membrane as I have described, will occa- 
sionally be seen in the female parts; but it has such an ap- 
pearance as may be easily destroyed in the preparation of the 
parts, if the anatomist be inattentive or careless. It is neither 
a guard, nor is its existence a test of female chastity. Often in 
tender children there is no such thing to be seen ; while, on 
the other hand, it has been cut to admit of labour and de- 
livery.* Either of these facts is sufficient proof of the idle 
notions entertained concerning this membrane, and that when 
present, it is, like a contracted preputium in the other sex, a 
defect. 
The carunculjE myrtiformes—are small and irregular tu- 
mours at the back, or lower part of the external orifice; they 
are seated rather at the sides than exactly at the back part; 
they are supposed to be the ruins of the hymen, which being 
lacerated, shrink into two or three tumours on each side. 
Some have said, that these exist originally joined together by 
a thin membrane, or delicate tissue of small vessels, the rup- 
ture of which causes an effusion of blood. They seem to be 
simply corrugations of the inner membrane, which serve as a 
provision for the dilatation of the parts; and they accordingly 
disappear during the passing of the child’s head. 
I he fossa navicularis is a sinus, supposed to be of the 
shape of a boat, whence its name. It is formed betwixt the 
* I need not sav how unnecessary and improper such operations are. All 
rigidity, callosities, even tumours, and undoubtedly the hymen, will yield to 
that general relaxation of all the parts, which takes place upon the commence- 
ment of labour. THE EXTERNAL PARTS OF GENERATION. 
317 
proper orifice of the vagina and the fourchette, or joining of 
the labii at their lower edge. It is more conspicuous in young 
subjects. 
From the meeting of the labii below, the perineum com- 
mences : it includes the space from the frenum to the anus. 
CHAP. II. 
OF THE PARTS CONTAINED WITHIN THE FEMALE PELVIS. 
These parts are, the bladder of urine, the vagina, the 
womb, the ovaria. We shall consider them under distinct 
sections. 
SECTION I. 
OF THE BLADDER OF URINE. 
As the coats of the bladder of urine in woman do not vary 
from those of the male bladder, we have under this head only 
to notice the peculiarities in its relative situation. It is seated 
behind the os pubis, and betwixt it and the womb ; and on its 
lower part it is attached to the vagina ; upon the neck of the 
bladder, or the beginning of the urethra, there is not a body 
like the prostate gland ; and, as we have seen, the urethra is 
short, wide, and straight, and simple in its use. 
Women are not subject to calculi, and the operation for the 
stone is rare in them ; for, as already observed, when the 
nucleus is formed, or when a stone slips down from the pelvis 
of the kidney, it passes from the bladder with much greater 
facility than in the male parts. The urethra of itself has been 
known to dilate so as to allow very large stones to pass, or it 
has been artificially dilated. Indeed the old operation for 
lithotomy was rudely to dilate, or rather tear, the urethra, and 
the modern operation is simply to thrust the gorget along the 
grooved staff, so as to lay open the side of the urethra and 
neck of the bladder, by an incision above the vagina. Some- 
times nature has effected her own relief by the stone working 
from the neck of the bladder into the vagina. 
A woman had for a very long period suffered great distress, 
not only the ardor urinse, frequent desire to make urine, with 318 
OF THE BLADDER OF URINE. 
the urine turbid and bloody, and with all the usual symptoms 
of stone violently aggravated ; but she was delicate and timo- 
rous, and concealed her distress, until the urine had run for 
some time by the vagina. After she had been exhausted by 
long suffering, her friends insisted that she should allow an ex- 
amination, when a stone was found partly in the bladder, with 
one of the rough ends projecting into the vagina. The open- 
ing was enlarged, and the stone extracted. 
We must, in all cases, recollect the connection of the upper 
part of the vagina and orifice of the womb, with the back part 
of the bladder. We have seen its effect in producing retrover- 
sio uteri. We must also attend to this connection, as tending 
to the displacement of the bladder in the procidentia uteri. 
The uterus sinking into the vagina, and the upper part of the 
vagina being at the same time reflected into the lower part, 
pulls down the bladder with it, and when (the disease increas- 
ing) the womb covered by the vagina comes to hang from the 
external parts, it has happened that the bladder has sunk down 
and lain upon the forepart of the tumour, but of course within 
the everted vagina. 
Third Plan. 
Section showing1 the effect of Procidentia on the Bladder. 
Thus, by comparing this fourth plan with the first of the 
female pelvis, we may judge of the nature of this displace- 
ment of the womb, and its effects on the bladder of urine. 
A, the os pubis ; B, the sacrum ; C, the intestines come 
into the situation of the womb ; D, the uterus fallen down, 
and carrying the vagina before it; E, the vagina still covering 
the womb, but the orifice of the womb appearing, which is OF THE VAGINA, &C. 
319 
generally distorted and irregular; F, the bladder, which, from 
its attachment to the forepart of the vagina, has been dragged 
down, but is now within the vagina. 
In such displacement of the bladder, the urethra becomes 
distorted from its natural direction, there is an obstruction of 
urine, and the catheter is with great difficulty introduced. We 
shall, perhaps, have to turn the handle of the catheter in vari- 
ous directions after introducing the point, and by chance get 
it introduced at last. 
SECTION II. 
OF THE VAGINA ; OF ITS SHAPE, CONNECTIONS, &c. 
The vagina is a tube stretching from the external orifice t© 
the orifice of the womb. Its orifice is bounded below by the 
fourchette ; above by the arch of the pubis ; and directly over 
it, or sometimes within it, is the orifice of the urethra; below, 
are the carunculae myrtiformes. It is surrounded by fasciculi 
of fibres, which are called the sphincter muscle. The canal 
of the vagina is of a conical form. At the outer orifice it is 
constricted by the sphincter muscle : but it is wider within, 
and where it receives the orifice of the womb. It may be 
distended to almost any degree, but naturally its sides, by 
their own elasticity, the fulness of the veins which are upon 
it, and the contraction of the surrounding fibres, are in contact. 
In the natural state, the orifices of the vagina and womb are 
but three or four inches distant, often only two; and some- 
times, where there is a degree of relaxation, they are nearly 
in contact. In the first months of pregnancy, the orifice of the 
womb is kept down by the degree of difficulty the body of the 
womb has in shooting up from the brim of the pelvis. But 
the gravid uterus rising above the pelvis in the latter months, 
draws up the orifice of the womb and stretches the vagina. 
The vagina bends gently round the pubis, as it were, or 
follows the axis of the pelvis ; and as the interior of the two 
circles cut off by the same radii s the shorter, the vagina is 
longer behind than before. 320 
®r THE VAGINA, &( . 
And thus (in this fourth plan) the forepart of the vagina A, 
is shorter than the back part B. We may observe from this plan, 
also, that the orifice of the womb C, projects as it were into 
the vagina, so that the finger touches the os tincse, and chiefly 
its anterior lip, without reaching the upper part of the vagina. 
The vagina takes its curve nearly in the centre of the pel- 
vis ; it is of necessity attached by cellular substance to the 
rectum and bladder. The urethra, as we have said, opens 
above the orifice, and that canal is attached to the vagina in its 
whole length; and the neck of the bladder is attached to the 
upper part. In consequence of this natural connection, disease 
of the vagina sometimes throws the whole parts, the rectum, 
vagina, and bladder, into one fistulous ulcer. 
The vagina has three coats ; that is to say, it has the inner 
coat, or surface, a few muscular fibres, and around it a conden- 
sation of the surrounding cellular membrane, which may be 
considered as the third coat. 
The internal, or villous coat, is a reflexure of the delicate 
covering of the external parts. It is of larger extent, or longer 
than the others ; and is therefore tucked up into rugae, which 
run across the vagina. They are more remarkable on the fore 
and back part of the vagina; they are less in married women, 
and considerably obliterated by repeated labours. 
To supply a viscous secretion for the defence of this surface, 
mucous glands are numerously, but irregularly, scattered over 
it, and they are particularly numerous at the orifice. 
The muscular coat is not very strong, nor are the fibres dis- OF THE VAGINA, SiC. 
321 
tinct, from which some have suspected their existence, alleg- 
ing, that there is here only condensed cellular membrane, and 
that the contraction of the vagina is the effect of mere elasti- 
city. I observe so great a profusion of venous vascularity, that 
I presume the vagina suffers an inflation of its coats, and con- 
sequently contraction from an afflux of blood to it. The mus- 
cular fibres are, however, as we have said, gathered into fasci- 
culi near the orifice, so as to be distinctly visible. 
The firmness and structure of the vagina supports the womb; 
the dilatation of the vagina, the relaxation which old age, and 
frequent labours produce, occasion the falling down of the 
womb. It is a disease almost peculiar to those who have 
borne many children, to the old, weak, and relaxed, and to 
those who are subject to the fluor albus; every flux from the 
womb, or discharge from the vagina, having a remarkable 
effect in relaxing the parts. 
This, from the nature of the parts, must be an increasing 
disease ; for no sooner has the womb fallen down into the va- 
gina, than it becomes a source of irritation, excites a bearing- 
down pain like tenesmus, an uneasy sensation, a desire to make 
urine, and an obstruction of urine; all which is explained 
by the connection of the parts. The womb lodging in the 
vagina dilates the orifice, and presses long on the perineum, at 
last it is entirely forced out, and the prolapsus uteri becomes 
the procidentia uteri: it is in truth a hernia of the womb. 
The third, and outer coat, as we have said, is formed of the 
cellular membrane, by which it is connected with the surround- 
ing parts ; but the peritoneum comes down upon the upper 
part of the vagina. This is the reason why a portion of the 
intestine, when it slips down betwixt the vagina and rectum, 
forms a kind of hernial tumour in the vagina, and why the water 
of the ascites has pushed down the back of the vagina, so as to 
make a bag capable of being punctured to draw off the water. 
For the greater space, however, the outer cellular coat of 
the vagina connects it with the urethra on the forepart, and 
with the rectum behind. From which close connection of 
parts, we see the consequence of the delay of the child’s 
head in the second stage of labour, that the head lies vio- 
lently distending, and compressing the parts, while the woman, 
exhausted by the previous stage, is unable to complete the 
delivery. From violent inflammation, with a deficiency of 
secretion, there arises a cold and flabby state of the parts. 
When the woman is delivered, the parts have suffered so 
much, that they slough off; sometimes the urethra is laid open 
on the forepart, and sometimes the rectum behind. 322 
OF THE WOMB. 
SECTION III. 
OF THE WOMB. 
Fifth Plan of the Female Paris. 
Uterus and Tubes. 
This little drawing will better explain the figure of the womb, 
when dissected from the vagina and surrounding membranes, 
than the usual reference to a bottle, a pear, or a powder-flask. 
As, indeed, it resembles no familiar object that I know, we 
must, for the convenience of description, distinguish it into 
these parts :—The upper part, or fundus, which is that part 
above the going off of the Fallopian tubes. The body of the 
uterus, which is that larger part betwixt the fundus and the 
narrowing below; the cervix, which is the narrow neck ; 
and the os tinc.e, or orifice formlcl of the bulging lips, which 
project into the vagina, of course that part over which the 
inner membrane of the vagina is reflected. We distinguish 
also the two surfaces, for the womb is of a flattened form. 
The anterior surface of the body of the womb is convex, but 
the posterior surface is considerably more so, and even during 
gestation it keeps this relative figure. 
The whole size of the uterus is about three inches in length, 
and two in breadth, but there is a very great variety in this 
respect, from age, the effect of pregnancies, and other causes. 
When in its usual situations and relations, the fundus is on a 
level with the brim of the pelvis, or a very little below it. In 
the foetus, the womb is like the bladder, considerably above 
the brim of the pelvis ; but in a few weeks the pelvis enlarging. of the womb. 
323 
it sinks deeper and soon assumes the same situation as in the 
adult. 
Fallopian tubes. From the lateral obtuse angles formed 
betwixt the fundus and the body of the uterus, the Fallopian 
tubes are continued. These tubes may almost be considered as 
a continuation of the uterus did not we find them so very dis- 
tinct in their substance. They are about three inches in 
length, take a tortuous course, and their extremities have an 
unequal fringed termination, which is called the fimbri.e. 
Their canal is very small towards the uterus, but enlarges ; 
and is patulous towards the extremities. These canals are the 
communications by which the ovum formed in the ovarium is 
carried down into the womb. 
Ligaments of the uterus. To support the uterus from 
sinking too deep into the pelvis, and to steady it, and direct it 
in its ascent during pregnancy, anatomists have generally as- 
signed as the use of the ligaments. But whatever good they 
may do in the latter operation, they are certainly unfit for the 
former. 
There are four ligaments of the uterus. 
The broad ligament of the uterus is formed of the peri- 
toneum ; for this membrane passing down before the rectum, 
and ascending again, and covering the neck, body and fundus 
of the womb, descends on the forepart, so as to reach the vagina 
before it rises over the bladder. Thus it invests the womb as 
it does the abdominal viscera. This investing of the womb 
with the peritoneum is indeed a provision tor its becoming an 
abdominal viscus, for in pregnancy it rises out of the pelvis ; 
and being distended before the bowels, assumes in every re- 
spect that relation to the peritoneum which they have. 
As the womb is included betwixt the duplicature of the peri- 
toneum, it is this peritoneal coat, which being continued off 
laterally, forms the broad ligament of the womb. This dupli- 
cature of the peritoneum being a thin expansion of it, has some- 
times had the name of ali vispertilionis : it is in truth like a 
mesentery to the womb and Fallopian tubes, and serves equally 
to support and convey the vessels to them. The womb and 
these two ligaments make a complete partition running across 
the pelvis. 
From the side of the uterus, a little below, and before the 
going off of the Fallopian tubes, the round ligaments arise. 
They are not merely condensed and elastic cellular membrane; 
but are composed of fibres with an intermixture of blood-ves- 
sels, so that whilst they keep a degree of tension on the uterus, 
they yield and grow not only in length, but in thickness and 
* Morsus diaboli. 324 
01 THE WOMB. 
strength, as the uterus ascends in the advanced pregnancy : 
they pass through the abdominal ring, and are attached to the 
cellular membrane of the top of the thigh. In the gravid 
uterus, both the broad and the round ligaments considerably 
alter their position, appearing to rise lower, and more forward 
from the womb than the unimpregnated state. This is in con- 
sequence of the greater increase of the fundus of the womb, 
in proportion to the lower part of it. 
What I have here described, and which are commonly 
called the round ligaments of the uterus, are the tendons ol 
the ligaments, and have a very particular use which authors 
have not observed ; at their upper extremity they terminate 
in a muscular coat, which is spread over the fundus of the 
uterus diverging from the tendon. The use of these tendons 
is to move the uterus in the first approach of labour, and to 
present the orifice of the uterus to the axis of the pelvis. 
OF THE CAVITY OF THE UTERUS. 
Sixth Plan. 
l'he cavity of the uterus is properly confined to the fundus 
and body, and takes a triangular figure. In the cervix, it is 
more like a canal, and differs essentially from the proper ca- 
vity. A, the cavity of the uterus ; B, the continued cavity, where 
it is very narrow towards the cervix. C, the canal of the cervix, 
where it has an enlargement like a sinus. The Fallopian 
tubes are seen going oft' from the cavity of the uterus. These 
angles of the cavity admit no more than a hog’s bristle. The 
third angle, towards the neck, is, of course, considerably larg- 
er. The proper triangular cavity of the uterus is lined with OF THE WOMB. 
325 
a peculiar soft and delicate membrane ; it is very vascular, 
and the vessels either open on the surface naturally or burst- 
ing out, from time to time, pour out the menstrual blood. The 
canal of the cervix shows a very different surface. We ob- 
serve a prominent longitudinal line on the fore and back part 
of it, from which oblique and transverse rugae go out. The 
surface is firmer and callous, and less vascular. Betwixt the 
rugae there are lacunae, which throw out a mucilaginous fluid; 
and towards the orifice we see these larger and sometimes 
distinct glandular bodies. 
This peculiar shape of the cavity of the womb, and the 
hardness and small degree of vascularity of the lower part, is 
of the most essential importance. The upper part, the pro- 
per cavity of the womb, is prepared for the reception and im- 
mediate adhesion of the ovum, when it shall have descended 
through the Fallopian tube; but the long callous cervix is 
provided, that there may be no adhesion to the lower part of 
the womb, and that the placenta may not form over the ori- 
fice of the womb, for if it should, the most dangerous kind of 
flooding takes place on the approach of labour, from the open- 
ing of the orifice, and the tearing open of the adhesions of the 
placenta, before the child can be delivered. The length of 
the cervix, and the glandular structure of the orifice, is also.of 
much importance in sealing up the cavity of the womb after 
conception, that there may be no longer communication with 
the vagina; for this purpose, a viscid tenacious mucus is 
poured out; but, on the approach of labour with the soften- 
ing and relaxation of all the soft parts, this adhesion and glu- 
ing up of the orifice is dissolved, and a more fluid secretion is 
poured out. 
From the cavity of the womb the menstrual blood is dis- 
charged at certain periods, from the time of puberty to the 
approach of old age, when the system is no longer capable of 
giving nourishment to the foetus. 
It was long disputed from what source the menstrual dis- 
charge flowed. Some affirmed, that it must flow from the 
vagina, and not from the womb, because it flowed sometimes 
during gestation. This is a fact which cannot be denied. 1 
have attended a patient who menstruated during the entire 
period or to the eighth month; and I have often observed 
ladies to menstruate at the first period after conception. On 
the other hand, we have every proof of the discharge being 
from the orifice of the womb. For instance, some have ob- 
served on dissection of the parts of women dying during the 
flow of menses, that blood was effused under the delicate mem- 
brane of the cavity of the womb. The vessels there have 326 
01' THE WOMB. 
been observed particularly turgid, or the whole surface of the 
proper cavity, and especially the fundus, spotted with bloody 
effusions. More particular observation has shown not only 
the mark of blood poured out from the inner surface, but that 
the whole substance of the womb was become thick, soft, and 
vascular;* and M. Littre affirms that in the body- of a woman 
who had died during menstruation, and with a conception in 
the Fallopian tube, he found a layer of red coagulated blood ; 
upon removing which he saw a number of small foramina 
which admitted bristles.f 
But the best and least equivocal proof is that which has 
been repeatedly observed in the inversion of the womb, when 
the inner surface has been turned out after labour, and has 
remained thus inverted, and protrudingfrom the external parts, 
for then the menstrual blood has been seen to distil from the 
surface of the cavity of the uterus. 
OF THE BLOOD-VESSELS OF THE WOMB. 
These are four large, arteries which supply the system of 
the womb, and four large veins which return the blood. 
The spermatic arteries come down from the aorta itself, 
or from the renal or capsule arteries. The spermatic artery- 
taking a waving direction, becomes tortuous in a most remark- 
able degree as it approaches the uterus : it is distributed to 
the Fallopian tube, the ovarium, but chiefly to the body and 
fundus ol the uterus, where it forms remarkable anastomoses 
with the artery- of the other side. 
The lower artery-—the etterine artery, comes in 
general from the hypogastric artery-, takes also a serpentine 
course, and is distributed to the vagina, and the lower part of 
the uterus, and inosculates largely with the other vessels, both 
in the uterus, and by- particular branches on the side of the 
uterus. 
In the first place, it appears, that this copious supply of ves- 
sels to the uterus, from four different sources, is a provision 
that the womb and secundines shall not by any accident of 
position, or by- the progress of labour and the consequent com- 
pression of one or both the lower vessels, be deprived of their 
due supply of blood. Again, their tortuous forms give proof 
of their occasional greater activity, that they admit of a pecu- 
* The authorities upon this subject are Spigelius, Morgagni, M. Littre, 
Moriceau, Winslow, Sympson. 
f ’1 his might have been an early abortion, or perhaps the decidua, which it 
s siud is sometimes formed at the menstrual period. OF THE WOMB; 
327 
liar and local action during menstruation, and that the blood 
will move more languidly when the stimulus of the womb has 
ceasecl. It is also a provision for the growth and increase of 
the womb, and the supply' of nourishment to the ovum ; and 
that an increased activity in apart must be supplied by a more 
tortuous form, as well as an enlargement of the calibre of the 
vessels, in a particular manner illustrated by the change which 
takes place in these vessels during pregnancy. For they be- 
come in a much more remarkable degree tortuous and en- 
larged. 
The substance of the uterus is said to be spongy and com- 
pact, which though it is a seeming contradiction in words does 
yet really convey an idea of the effects of the intertexture of 
vessels in it. Some have said, (as Moriceau,) that by preg- 
nancy the womb is distended, and grows thinner : others, that 
it grows thicker, as Daventer: and others again, as Smellie, 
assert, that it continues of its natural thickness. These asser- 
tions are none of them perfectly correct; for the womb is not 
distended by the growth of the foetus and membranes, but 
grows with them. Again, that the substance of the womb 
grows in a remarkable degree is true, but still when distended 
by the waters in the last months of pregnancy, its walls are 
thinner than in the unimpregnated state. Thus, when it has 
been cut in the living body, upon the approach of labour, as 
in the Cesarean section, I have observed it, not more than a 
quarter of an inch in thickness, even at the part to which the 
placenta adhered. When I have dissected the womb after a 
tedious labour, the waters discharged, but the head wedged in 
the pelvis, I have found it considerably thicker. And, lastly, 
in the full contraction of the womb, after expelling the fcetus 
and placenta, (for example, in rupture of the womb, where 
the child and placenta had been forced amongst the bowels, 
and the woman soon after died,) I found the walls of the 
womb more than an inch in thickness. 
SECTION IV. 
OF THE OVARIA. 
The ovaria are two oval bodies which are suspended in the 
broad ligament behind, and a little below the Fallopian tubes : 
while they have an oval figure, they are somewhat flattened. By 
cutting out the ovaria, the animal loses the power of conceiving, 
and desire is extinguished ; they, therefore, bestow what is 328 
essential to generation upon the part of the female. In vague 
speculations on the subject of generation, they were supposed 
to prepare a female semen! but more particular examination 
demonstrates that they consist of vesicles which are ova ; but 
how far incomplete, or in what essential circumstance requiring 
the approach of the male is not determined. 
When we hold the section of the ovarium betwixt the eye 
and the light, we see a great many pellucid vesicles; and if 
we examine the ovarium of an animal killed in full health, and 
particularly in the season, we shall observe these ova to be in 
all varieties of states of preparation for impregnation. Some 
small and pellucid, and yet only discernible in the thick 
outer coat, by having a degree of greater transparency ; others 
which have taken a slight tinge of bloody colour from vessels 
striking into them ; and if the section be made after a minute 
injection, the vesicles will be seen coloured in the proportion 
of their maturity ; some without, a speck of colour ; others 
tinged ; one or two loaded with injection; and some vascular, 
and particularly prominent. 
In very young girls, the substance of the ovarium is whitish, 
and very soft; the surrounding membrane is thick ; and the 
round corpuscles scarcely discernible ; and no irregularities, 
nor any of those bodies called corpora lutea, are to be seen on 
the surface. But as the girl advances in years, the little vesi- 
cles begin to appear, and when about ten years of age, or 
just before menstruation, the ovarium is full of ova of various 
sizes, and some of them more matured, and forming an emi- 
nence upon the surface. In the adult woman, the substance 
of the ovarium, which appeared as an uniform homogeneous 
mass in the foetus, is become a cellular and vascular bed, 
giving nourishment to those numerous vessels or ova. Before 
impregnation can take place, there must be a certain state of 
preparation of the ovaria, without which, the approach of the 
male effects no change in the uterine system. The lower 
animals having their seasons, and these seasons being a state of 
preparation for the male, impregnation follows the copulation 
with much certainty ; but, in woman, such a periodical revo- 
lution in the system, and instinctive desires, would but ill ac- 
cord with that superiority in attributes of the mind, which dis- 
tinguish us in the scale of beings. But women also suffer such 
an occasional excitement in the uterine system, though unac- 
companied with desire, Avhich preserves the womb in a state 
of preparation for the reception of the ovum, and the ovaria 
in a state of preparation for impregnation. This is the effect 
of menstruation. 
OF THE WONii. OF THE WOMB 
329 
OF PUBERTY. 
Authors have long, with many expressions of surprise, la- 
boured to assign a cause, or frame a theory, for the explanation 
of those changes which we observe in woman at the age of pu- 
berty : and generally, in their theories, they have connected 
with these changes the monthly and periodical discharges of 
blood from the uterus, which commences with puberty. These 
theories have been founded in general on principles remote 
from the laws of a living system. At this period of puberty 
the whole frame is expanded into the fulness of feminine 
beauty: the breasts rapidly increase, and are matured; the 
parts of generation are enlarged; the hair of the pubes grows, 
and the menses flow. In explanation of these changes, theo- 
retical conjectures after this model have been entertained. 
u About this time the growth of the body begins considerably 
to diminish, and the blood finding easy admittance into the 
completed viscera is prepared in greater quantity, the appetite 
being now very sharp in both sexes, a plethora consequently 
follows. In the male it vents itself frequently by the nose, 
from the exhaling vessels of the pituitary membrane being di- 
lated, &c.; and now the semen first begins to be secreted and 
the beard to grow. But, in the female, the same plethora finds 
a more easy vent downwards, being that way directed, partly 
by the weight of the blood itself to the uterine vessels, now 
much enlarged, of a soft fleecy fabric, seated in a loose hollow 
part, with a great deal of cellular fabric interspersed, which is 
very yielding and succulent, as we observe in the womb: for 
these causes, the vessels being easily distensible, the blood 
finds a more easy passage through the very soft fleecy exhaling 
vessels which open into the cavity of the uterus, as being there 
less resisted than in its return by the veins, or in taking a course 
through any other part; because, in females, we observe the 
arteries of the head are both smaller in proportion, and of a 
more firm resisting texture. The return of the same is, there- 
fore, more slow, both because the flexures of the arteries, from 
the increased afflux of the blood, become more serpentine and 
fit for retarding the blood’s motion,* and likewise, because 
it now returns with difficulty through the veins. The blood is 
therefore first collected in the vessels of the uterus ; next it is 
accumulated in the arteries of the loins, and the aorta itself, 
which urging on a new torrent of blood, augments the force so 
* I have shown that the tortuous arteries always form a provision for the 
occasional increase of the action and acceleration of the blood, 330 
Oi THE WOMiJ. 
fur as to discharge the red blood into the serous vessels, which 
at first transmit an increased quantity of warm mucus, after- 
wards a reddish coloured serum, and by suffering a greater 
distention, they at last emit the red blood itself. The same 
greater impulse of blood determined to the genitals, drives 
out the hitherto latent hairs, increases the bulk of the clitoris, 
dilates the cavernous plexus of the vagina, and whets the 
female appetite to venery,” &c. 
We cannot have trust in so weak a theory, we cannot believe 
in this plethora, produced by the diminished growth of the 
limbs; neither can we believe that congestion and plenitude 
are produced in the female system, from the deficiency of per- 
spiration, from their more lax and weaker solids compared with 
man, from their indolent and sedentary life: for facts are in 
direct contradiction. The growth and completed function of 
parts at this particular age, is not to be explained by any 
theory so partially applicable; during almost every period of 
life, there are similar changes taking place in some one part 
of the body. Parts lie dormant, and are stationary in their 
growth, which at a particular and stated age of the animal, en- 
large and develope themselves by a new and invigorated 
action. Observe how different the proportions of the foetus 
are from those of the adult. We see nature careful to perfect 
certain parts, as the head and liver, at an early period. We 
see during early childhood how the parts shoot out, and 
evolve in due proportion. We see parts which were large in 
the fetus lose their preponderance: we see others, which 
served some purpose in the fetal system, gradually shrink 
and disappear, because they have no longer the stimulus to 
action in the circle of connections which take place in the 
adult system. We find other parts, as the teeth for example, 
lying long within the jaw, instead of proceeding with a gradual 
and continued enlargement, suddenly rising at certain stated 
periods from their embryo state, and enlarging and pushing- 
up through the gums, when it becomes fit that the child 
should take more solid food than the mother’s milk. So the 
second set of teeth, in a more particular manner, lie quite sta- 
tionary in their growth within their little sacs, yet quickly, at 
stated periods, they increase, the enamel is formed, and they 
rise above the gum. There is an infinite number of such 
changes depending upon the same laws of the economy, and 
not different from those which control the growth, and direct 
the shape of parts. They depend upon certain laws of the 
constitution, which give an excitement to certain parts, at 
stated periods, and which no theory partially applicable will 
explain. There is a series in which the parts of an animal OF THE WOMB. 
331 
body are matured, and a succession in which the functions are 
brought to maturity ; and in the female constitution, there are 
laws determining an action upon the womb and breasts, and all 
parts subservient to conception and the nourishment of a 
lostus ; at that period when the woman is arrived at the age fit 
to take upon her the part of a mother. 
OF MENSTRUATION. 
Under this head, I shall confine myself to such a general 
view of the subject, as is necessarily connected with the pecu- 
liar functions we are now endeavouring to comprehend. 
Menstruation is a state of preparation for conception. 
When, therefore, the menses flow at the natural periods, and 
in due quantity, it is a sign that the woman may conceive, 
and that her system is fit for the support and nourishment of a 
child. It is a general affection of the system, which has a ten- 
dency to relieve itself by a topical action, by the excited action 
of the uterine system ; and this excitement of the uterine sys- 
tem is the end which nature is accomplishing. To explain 
this, I may be allowed to take a short prelintinary view : each 
particular organ or viscus, whilst it has its connections with the 
general system, is, in truth, a system within itself, having its 
peculiar functions, sympathies, and even vascular action, in a 
certain degree independently. 
Were not this in some measure the case, we should see no 
local disease or topical action ; and no vascular action could 
be for a moment stationary and confined to one part. The 
body would, indeed, be then only one great hydraulic machine. 
But while the several parts have the property of being excited 
separately to an accelerated action, they are actuated by re- 
mote sympathies, and by these sympathies and relations is the 
whole system in a great measure supported. 
Before menstruation commences, there is a preceding indis- 
position, and symptoms indicating a constitutional affection. 
And these complaints are usually more severe in the first than 
in the subsequent periods. The general revolution in the sys- 
tem begins to accumulate its action towards the womb, and 
those symptoms usually accompanying uterine irritation, show 
how far it is affected, and in a little time the menses flow. 
Now, I conceive the flow of the menstrual blood to. be, not the 
end which nature is here labouring to accomplish, but the 
means of allaying the excited state of the uterine system, after 
the object is accomplished. It is not the discharge of a few 
ounces of blood which relieves the system ; for drawing blood 332 
of the wostn. 
simply will not do it; but it is the excited action of the uterine 
system which relieves the general distress, and that topical 
action has full relief in the menstrual discharge. General and 
topical plethora are terms which have been of great service in 
explaining this periodical change in the female system, but 
the state of mere fulness has little effect either on the constitu- 
tional or topical change. Even in the exhausted and debili- 
tated state of the system, wrhen menstruation ceases from the 
want of energy and power in the vascular system, still there 
remain the same laws governing the sympathies and relations 
of the several parts ; and although they are feebly and imper- 
fectly excited, they give rise to accumulated distress at the 
period in which the menses should flow. 
With regard to vicarious hsemorrhagy from remote parts of 
the body, some, Avhose opinion I greatly value, do not con- 
sider them as deviations of the menses. At all events, from 
what I have seen of such haemorrhagies (tumours, for exam- 
ple, discharging blood at the menstrual periods,) I would ob- 
serve, that there is an excitement, throbbing, and distention, 
previous to tbe discharge of blood, which confirms me in the 
notion of the necessity of a counter excitement and action, as 
well as the discharge of blood, being necessary to make a de- 
rivation from the uterine vessels. It is by dissection alone that 
we can form a correct opinion regarding the final use of the 
periodical return of the menses. 
By dissection we come to the knowledge of the most essen- 
tial facts. In the first place it is found, that the ovaria, and 
their vessels, partaking of the general excitement of the sper- 
matic arteries, are enlarged, full of blood, and with every sign 
of increased action. We find also, that the ovaria are matured 
and brought to pullulate, and almost to start from their invest- 
ing membranes. Without the ovaria are in this state of pre- 
paration, conception cannot take place. In considering this 
subject of menstruation, the mere circumstance of the dis- 
charge of blood has been too much thought of, while the other 
more essential circumstance, the -change upon the ovaria, has 
been neglected. The end of this periodical excitement is to 
ripen the ovum, the flow of menstrual blood to allay the ex- 
cited state of the uterine vessels. Accordingly, if conception 
should take place, the excitement proceeds, and no flow of se- 
creted blood takes place during the period of gestation. 
It is not easy to determine, says Haller, either in this or in any 
other spontaneous haemorrhagy, from what kind of vessels the 
blood flows. From the circumstance of the hasmorrhoidal 
discharge, which certainly is from veins, and from the lochia, 
which is generally supposed to be a discharge from the venous. or THE WOMB. 
333 
sinuses of the womb after delivery, we have the argument of 
analogy, that in menstruation also it is a venous discharge. 
This opinion is further confirmed from stagnant blood being 
found in the uterine veins of women dying during the flow of 
the menses, and orifices being observed larger than could well 
be supposed to be the extremities of arteries. 
I would say, that it is little probable that spontaneous hte- 
morrhagy proceeds from the rupture of the extreme arteries, 
because it is the activity of the arteries which causes the hae- 
morrhagy; and because this activity is the exertion of a mus- 
cular force, and the exertion of a muscular fibre never is such 
as to tear the fibre itself. On the other hand, we observe that 
it is the necessary consequence of an increase of the action of 
arteries, that the corresponding veins dilate, and seem to suf- 
fer a force of distention proportioned to their increased acti- 
vity. We must not forget that many are of opinion, that 
the menstrual blood flows from the exhaling arteries. This 
opinion must rest upon argument, and not facts, unless the 
assertion of Rauw be taken as proof, that he could distin- 
guish their mouths ; or that of Meibomius, who said he in- 
troduced bristles into them. That anatomists have intro- 
duced bristles into pores, or foramina, it would be ungracious 
to doubt, but that these were the orifices of exhaling arteries, 
is difficult to believe. I rather imagine, that there is a pro- 
vision for this evacuation in pores, or foramina, in the ex- 
treme veins on the vascular inner surface of the womb. 
From the consideration of the cause of menstruation, as I 
have conceived it, from the symptoms which precede and 
accompany it, and from the effect attributable to the men- 
strual action on the uterine system, we cannot consider it as 
a mere evacuation of blood, but rather as of the nature of a 
critical discharge relieving the symptoms which preceded it. 
With regard to the opinion of its being a secretion, we must 
first know accurately what is meant by the term. If those 
who suppose the menstrual blood a secretion, mean only that 
the blood is changed by the action of the vessels of the womb, 
I should willingly acquiesce in their opinion; for even during 
the bleeding from the arm by the lancet, or from a common 
wound, the blood is altered in the space of the few minutes 
during which it flows ; and before the final stopping of a com- 
mon haemorrhagy, there is a change in the properties of the 
effused blood. 
When there is an unusual source of irritation in the womb, 
added to the natural and periodical excitement of the parts, 
the menses become more profuse, they last for a longer pe- 
riod, the time of their intermission is shortened, and, in the 334 
'or THE WOMB. 
end, from some diseases of the womb, there is a perpetual 
oozing of blood, which debilitates the woman, and destroys 
her constitution, or there is sudden and profuse discharge with 
coagula, unlike the usual evacuation. 
OF THE CHANGE PRODUCED BY THE UNION OF THE SEXES. 
In considering those changes produced on the ovaria and 
womb by impregnation, we must have recourse to analogy in 
the first instance. By attending to the changes produced in 
vegetables, and the lower animals, we may be enabled to com- 
prehend such of the changes in the female organs consequent 
upon conception, and which we might not otherwise be ena- 
bled to understand. 
We see that vegetables propagate their branches in every 
respect like the parent trunk. We see in the autumn the bud 
lodged in the axilla of the leaf, and observe it pass through the 
winter in a kind of dormant state; but when it is influenced by 
the returning heat of the spring, it shoots out to full maturity. 
This growth is a natural power of propagation and increase, 
marked by no very peculiar circumstances, yet bearing a strong 
analogy to the production of the seed. 
In the formation of the fruit of the same tree, we see a more 
complicated provision for the propagation of the plant. We 
And that although the seed appears to be formed by the natu- 
ral growth of the part like the bud, yet before it becomes pro- 
lific, and capable of growing, and arriving at maturity, it must 
be influenced by circumstances similar to the union of the sexes 
of animals ; that its power of reproduction depends upon the 
reciprocal action betwixt the parts of the same plant, or by 
the approximation of male and female plants. 
Between the formation, maturity, and impregnation of the 
seed of plants, and those of the ova of animals, there is a 
close analogy. The seed is formed and matured while at- 
tached to the parent plant; but the vessels of the plant having- 
completed this operation, shrink from their connections with 
the seed, leaving it with its little system of vessels complete, 
and with a kind of imperfect life, which may be considered as 
analogous to a dormant state. This imperfect life, or perhaps 
a state merely capable of being excited into life and motion, 
continues for the winter season, or for a longer period. 
The flower of plants solicits the fluids to the seed, as the 
influence of the leaf cherishes the bud in the axilla. The pulp 
of the fruit is probably a provision of the same kind, or when OF THE WOMB. 
335 
it has fallen, to lay the foundation, by its decay, of a soil suited 
to the tender plant. 
In the seed itself, we have much to admire. We find it in- 
cased in a strong husk, or shell, which is in general provided 
with a porous part ready to imbibe the moisture of the ground. 
In the nut within the outer shell, there is a soft spongy sub- 
stance, which, receiving the moisture, swells and bursts up the 
shell, and relieves the seed. The kernel of the nut is then 
like a common seed, it has begun to vegetate, and these are 
the parts which form the system of its economy. The prin- 
cipal part of the seed consists of albuminous matter for the 
supply of the nourishment to the embryo plant, so as to pro- 
long its shoots, and to send down its roots into the earth. The 
little embryo plant lies complete in all its parts, betwixt the 
lobes of albuminous matter, in a state of torpor, or in which 
the operation of the living principle is suspended. From the 
embryo plant there extends into the albuminous matter of the 
seed, vessels or tubes, inactive, but ready, on the supply of 
heat and moisture, to absorb the nutritious matter of the 
albumen, and minister to the increase of the embryo plant. 
Now the root of the little plant sprouts from the seed, and 
has a tendency to strike into the ground, and the bud rises to 
the surface towards the light, and the influence of the at- 
mosphere. 
We see in this instance, that the operation of the system of 
tubes of the embryo plant in the albumen was merely sus- 
pended, that upon the seed being put into the ground, the 
heat and moisture promote the germination, by driving the 
nutritious matter of the albuments to the embryo plant. In 
the first stage of this change, the matter absorbed by the ves- 
sels of the albumen supply that nourishment, which afterwards 
is conveyed from the root striking into the earth, and from the 
leaves absorbing from the atmosphere. And when the roots 
have struck into the earth, and the first leaves rise upon the 
surface, the lobes of the albumen are exhausted and fade, or 
rise up in form of leaves, still cherishing the tender plants. 
When we come accurately to examine the situation of the 
embryo in oviparous animals, we shall find the same provision 
for the nourishment and growth of the young animals, inde- 
pendent of external circumstances, nourishment prepared foi 
it until it shall be enabled to gain strength to feed itself. 
The manner in which an egg is formed is this: The yolk, 
with its delicate membranes, are formed in the ovarium of 
the hen. The ovarium is placed on the back-bone, innume- 
rable yolks are seen gradually formed, and successively in- 
creasing in size. When they are matured, they are of the full 336 
OF THE WOMB. 
size we see them in the perfect egg; they are surrounded 
with a delicate web of membranes, extremely vascular, the 
membrane of the yolk bursts when it is mature and impreg- 
nated, and then it falls into or is grasped by the infundibulum, 
or what answers to the Fallopian tubes in woman and in quad- 
rupeds, While yet in the egg bed, the embryo is seen to be 
included in its membranes, upon the surface, or in the mem- 
brane of the yolk, it is called cicatricula; as the yolk, and the 
cicatricula, pass through the uterus, the yolk, in a most cu- 
rious way, has the addition of the other part of the egg. The 
uterus of a bird is not like that of other quadrupeds or vivipa- 
rous animals, simply for the reception of the ovum ; but it is 
long and convoluted like the intestines. And the yolk, as it 
drops into the upper part of it, collects as it passes along the 
uterus, the white of the egg, which is a secretion from it. As 
it proceeds downwards, it receives the membranes of the white, 
and before it is excluded, it is coated with the shell to pre- 
serve it from injury when it shall be dropt from the hen. In 
the fuily formed and incubated egg this is the situation of the 
parts. Under the shell is a membrane ■which invests the whole 
parts, but leaves a space containing air in the greater end be- 
twixt it and the shell. Within this membrane the glairy white 
of the egg is contained, and within the white or albuminous 
matter is the yolk. Under the membrane of the yolk, there 
is a small spot of a lighter yellow than the yolk. This, upon 
examination is found to be a vesicle, and within it we see a. 
lesser circle formed by an inner vesicle : this is cicatricula, 
and within this the rudiments of the chick are contained. We 
may observe, that the yolk is specifically lighter than the 
white; again, it is fixed, towards the two extremities of the 
egg, to the albumen, or white, by the chalaza. These are like 
twisted cords, which arise from the yolk, and expand in the 
white, so that they take a pretty firm hold on its tenacious sub- 
stance. These chalaza are not fixed to the yolk in its axis, 
but to the side, so that the buoyancy of the yolk keeps it re- 
volving as the egg is turned, so as always to present the cica- 
tricula to the upper part of the egg, in whatever way it is 
placed; consequently it is always contiguous to the body of 
the hen, so as immediately to receive the influence of the ma- 
ternal heat. By incubation, the principle of life in the chick 
and its membranes is roused, and the first perceptible change, 
appears in little bloody streaks, which, running together, form 
a circle of vessels, and which are seen to terminate in the 
umbilicus of the chick. 
This vascular circle, the most beautiful appearance of any 
in the economy of animals, ought to be particularly explain- OF THE WOMB. 
337 
ed. In Mr. Hunter’s book, treating of the blood, there is a 
plate which represents the embryo of the chick in the incubat- 
ed egg, at three different stages of its formation, beginning 
with the earliest visible appearance of distinct organization.— 
The preparations from which these figures are taken, form 
part of a complete series contained in Mr. Hunter’s collection 
of comparative anatomy.—1'hey are meant to illustrate two 
positions laid down in his work, viz. that the blood is formed 
before the vessels, and when coagulated, the vessels appear to 
rise ; that when new vessels are produced in a part, they are 
not always elongations from the original ones, but vessels new- 
ly formed, which afterwards open a communication with the 
original. 
This to me seems an idea founded on a very limited view 
of the state of the parts. We must recollect that this is not 
the formation of new parts or new vessels. The embryo is 
in that state of which I have endeavoured to convey an idea, 
by the term dormant; possessing that degree of life which 
is to be renewed by incubation, or artificial heat, but which 
will last a great length of time, and, like the germ in plants, 
be brought to vegetate only in particular circumstances. The 
tract of these vessels is laid in the original conformation of 
the embryo and surrounding membranes; they are now merely 
called into action, and we see only the effect of this action. 
We see red blood formed; we know that the redness of the 
blood is derived from the membranes, and matter which sur- 
round the embryo, and that it is conveyed to the chick or 
embryo. Before we allow ourselves to conjecture what is 
the first motion in the circle of actions which now take place, 
we must consider whether it be not more likely that the first 
action of these vessels is in absorption ; that is, an absorption 
in the extremities of these vessels, or is there first an action 
of the heart of the chick l—We are left to this question. Is 
it probable that a change shall take place in the fluids which 
shall stimulate the vessels ? or shall the heat of incubation 
stimulate the vessels te act upon the contained fluids ? or, as 
seems most probable, does the incubation, at the same time, 
produce a change in the fluids, and stimulate the vessels to ac- 
tion ? To explain my opinion, I shall describe the probable 
series of actions. 
In common seed the small germ of the plant has its ves- 
sels passing out into the lobes of the albumen to absorb the 
food, upon the existence of the peculiar circumstances neces- 
sary to its being stimulated to activity and growth. We have 
to observe, that where the nut was attached in its husk to the 
tree, it has left a porous part; by this cribriform kind of plate 338 
OF THE WOMB. 
the moisture of the earth enters ;—that dry scurfy substance 
which we observe on the inside of the shell, swells with the 
moisture, which also penetrates the albumen or kernel—the 
moisture forming a combination with the albumen prepares it 
for absorption ; the vessels are at the same time excited, ab- 
sorb, and thus nutritious fluids are conveyed to the germ—the 
nut splits by the swelling of the parts, and the corculum or 
bud sprouts up.—We find then, that in this instance the grain, 
or nut, is brought into action by the fluids absorbed, forming 
new combinations with the albumen or kernel, and the active 
exertion of the living powers, beginningby an operation in the 
fluids. 
In the same manner, I conceive, that the incubation of the 
egg causes an action first in the fluids, not in the solids (for 
these are solids according to the strictest signification of the 
term, and strong membranes, as a little vinegar will show, 
when poured upon the albuminous substance of the egg). A 
change takes place in the fluids, there are new arrangements 
suiting them for absorption, by those circles of vessels which 
are laid on the original formation of the membrane. The 
fluids act as a stimulus to those vessels, whose alternate action 
and relaxation never cease until the termination of life. I 
conceive this explanation, which I have offered, to be more 
consonant with the great principles of physiology, and an ex- 
tensive analogy of similar actions in the economy, than that 
• explanation of Mr. Hunter, which supposes the specks seen at 
the sides of the vessels, to be spots of coagulated blood, des- 
tined afterwards to become blood vessels. For, I am apt to 
conceive, the red blood to be formed only after several rounds 
of the circulation, and to depend upon a more perfect assimi- 
lation than that first excited : and that Mr. Hunter is all along 
in this mistake, that he is supposing these vessels to be newly 
formed, which are laid in the constitution of the membranes 
surrounding the embryo, and -which are now only called into 
action, and only become apparent when they convey red 
blood. 
In the system of the egg thei'e are other circumstances wor- 
thy of notice : as the chick grows by the absorption of the 
white, or albumen, the new combinations reduce to a lesser 
bulk the whole mass, which is within the shell, and now we 
perceive the use of the air-cell, which enlarging fills up this 
space. When the chick has escaped from the shell, the yolk 
of the egg is not exhausted, but it is found to be received into 
the belly of the chicken, and to have a conduit leading into 
the duodenum, by which it is poured into the intestinal canal. 
It is for some time a source of supply to the young animal until OF THE WOMB. 
339 
its strength is equal to the digestion of its appropriate food. 
And in this respect it is analogous to the suckling of vivipa- 
rous animals. 
Let us now observe what analogy exists betwixt the gene- 
ration, or rather the birth and nourishment of the embryo of 
the viviparous animal, and those of the oviparous. As to the 
precise effect which the approach of the male has upon the 
ovarium of the female, whether, by this union of the sexes 
there is an actual addition to the ovum, or only an influence 
exerted on the parts already there by the presence of the 
male semen, it seems almost needless to hope for an abso- 
lute decision. 
The resemblance of the offspring to both parents would in- 
fluence us at once to conclude, that there must be a union of 
the parts from both sexes. But when we consider how much 
the peculiarities of individual animals depend upon certain 
peculiarities of action ; how the constitutional predispositions 
must depend on the same peculiarity in the action of the ves- 
sels, since the doctrine of absorption teaches us, that of actual 
substance nothing is permanent, but all suffers an incessant re- 
volution and change, we are forced to conclude that nothing 
can remain but certain peculiarities of action, and we may 
then come to allow, that the male semen merely influences the 
state of the parts already formed, and does not bestow an ac- 
tual substance. 
In the speculations on the subject of generation, facts and 
observations have been so very rarely attended to, that those 
which have been offered seem to have had a preponderance 
much beyond their real value. Thus the microscopical de- 
monstration of animalculae swimming in the semen of the 
male, has given birth to an idea that they were homunculi, 
which being introduced into the proper nidus of the female, 
grew up to man’s estate. Though, where all is conjecture, 
and, perhaps, as no better explanation is to be offered, it may 
seem improper so directly to contradict any theory, still I must 
say, that this is, in my mind, the height of absurdity. To sup- 
pose an animal secreted along with the seminal fluid from the 
testicle of the male (and which, in all probability, is the pro-* 
duction of stagnation and putridity,) to swim and be nourished 
in the male semen, and yet to hold that on being introduced, 
into the ovaria, it changes from an active animal into an im- 
palpable gelatinous-like mass, and, after a series of changes, 
grows at last to the maturity of a human being, is altogether 
beyond my comprehension. 
The experiments made by the ingenious Dr. Haighton, 
throw considerable light upon these delusive speculations re- 340 
01 THE WOMB. 
garding the impregnation of the female. He found by expe- 
riments on rabbits, that upon cutting the Fallopian tubes, for- 
ty-eight hours after the coitus, the impregnation was equally 
obstructed as when he had cut them previous to admitting the 
male ; it would appear that in these animals impregnation is 
by no means the instantaneous effect of the union of the male 
and female, but that it requires at least fifty hours ; for, when 
Dr. Haighton cut the Fallopian tubes at that period, it did not 
prevent impregnation. Dr. Haighton proves, that the gene- 
rative process is not an instantaneous effect, as wre should very 
naturally suppose, but an operation requiring time. That the 
semen does not reach the ovaria during, or immediately after 
the coitus, is sufficiently evident ; and it is still more so that 
the ovum is impregnated while in the ovarium, and not upon 
its descent into the womb, which is proved from the foetus 
sometimes remaining in the ovarium, or tubes, and growing to 
maturity. Dr! Haighton supposes the semen only to affect the 
vagina and uterus, and that a consent of parts, or sympathy, is 
communicated along the tubes and ovary to the ovum ; and 
that neither the semen nor the aura seminales reaches the ova- 
ria. When we look abroad for analogies, however, and find 
the semen of some animals, as fishes, merely thrown out upon 
the already evacuated spawn, we cannot readily acquiesce in 
this opinion of the mere sympathy of the female parts calling 
the young animal into life. 
Leaving this subject we have to observe, that previous to 
impregnation there is a ripeness and prominence of some 
of the ova, that by coition the Fallopian tubes do not in- 
stantly grasp, impregnate, and cause the bursting of the 
ovum from the ovarium ; but there is an action commenced 
which gradually brings about this change. Whilst the ovary 
is thus affected, the tubes are preparing for their action of em- 
bracing the ovum, there is an increased turgescence in then- 
vessels, and an enlargement and swelling of the fimbriated ex- 
tremity. When thus prepared, it approaches the ovarium, 
grasps, and receives the ovum, and by a peristaltic motion, 
probably very slow and gradual, the ovum is conveyed into 
the cavity of the uterus. 
OF THE OVUM, AND ITS CONNECTIONS WITH THE UTERUS lN 
THE EARLY MONTHS OF PREGNANCY. 
The ovum, when it has descended into the uterus, and is 
perfect in its structure, is a soft oval mass, fringed with ves- 
sels, and composed of membranes containing the early foetus, OE THE WOMB. 
341 
When opened, or dissected, it presents three cavities, or we 
observe the fetus to be surrounded with three distinct mem- 
branes. The 1. Decidua, or tunica filamentosa, false chorion, 
or spongy chorion. 2. The chorion. 3. The amnios. Of 
these coats, the outer one is formed by the womb,* the others 
constitute the ovum as it has descended from the ovarium. 
We shall, in the first place, attend to the original membranes 
and general constitution of the ovum, and then to the decidu- 
ous covering tvhich it receives in the womb.* 
Plan of the Membranes. 
A, The Foetus. B, The Amnios. C, The Chorion. D, The 
Vesicula Alba. 
Amnion. The amnion is the vesicle which immediately in- 
volves the fetus. It is a very thin and pellucid membrane in 
the early .stage of pregnancy, but it acquires considerable 
thickness and strength in the latter months. 
The amnion contains a thin watery fluid in which the fetus 
is suspended. In the abortion of the early months, we find the 
quantity of this fluid very great in proportion to the whole 
ovum, and this forms a defence to the delicate and almost ge- 
latinous substance of the fetus, while it is a provision also for 
the regular presentation of the head of the child, for now the 
fetus being suspended in this fluid, and hanging by the umbili- 
cus, and the head and upper part of the body greatly prepon- 
derating, it takes that position with the head presenting to 
* See Albin. Ann. Acad. lib. i.cap. xviii. and six. Hunter’s tables of the 
Gravid Uterus.—Camper leones. 342 
OF THE WOMB. 
the orifice of the womb which is necessary to natural and 
safe labour, the foetus being prevented from shifting in the 
latter months by the closer embracing of the child by the 
uterus. 
Chorion. The chorion is the second involving membrane 
of the foetus ; on the inside it is smooth, and betwixt it and the' 
amnion a gelatinous fluid is interposed. In the early months 
it is much stronger than the amnios, but in the advanced stage 
it has come in contact -with the amnios, no fluid being betwixt 
them. And in proportion as the amnios gains strength to be 
of essential service in dilating the orifice of the womb during 
labour, the chorion has relatively become very thin and weak. 
On the outside the chorion is shaggy and vascular, and con- 
stitutes those minute extremities of the vascular system of 
the ovum, which attach to the surface of the womb, or rather 
to the fiocculent membrane which it throws out. 
The umbilical cord. Vv hen we can first discern the foetus, 
it is merely like an opaque oval body of the size of a common 
fly, and closely attached to the amnion ; but, by degrees, it 
recedes from it, and then we perceive that it is attached by 
the umbilical cord, which consists of the trunk of the vessels 
going out from the foetus, and which distributed upon the 
chorion receive the supplies from the maternal system. 
Now we perceive that the fcetal system which descends from 
the ovarium, is not merely a foetus or embryo, but that this 
embryo, besides a system of vessels within its own body, is 
surrounded completely with membranes, and that from the 
vascular system of the embryo, there go out vessels, which be- 
ing minutely distributed to the outer vesicle, or membrane, 
and actuated by the same heart which circulates the blood 
through it, our little corporeal system prepares for imbibing 
the due nourishment from the uterus. 
Vesicula alba. The vesicula alba, or umbilicalis, is a lit- 
tle vesicle which lies betwixt the chorion and amnion ; it con- 
tains a white fluid; it is connected with the navel or cord, by 
an artery and vein. Very little has been offered as explana- 
tory of its use ; it has been considered as similar to the alan- 
toes of quadrupeds, and having a connection with the urachus ? 
but it has no communication with the bladder, and soon dis- 
appears. Whereas, if it had been for receiving the secretion 
of urine, it would have been prepared for the more mature 
state of the foetus. 
I conceive it not to be improbable, that it is a provision of 
supply for the embryo, previous to its perfect attachment to 
the uterine system, and during its descent into the womb, per- 
haps similar to the albumen of oviparous animals, but which OF THE WOMB. 
343 
alter the perfect establishment of the connection betwixt the 
fetal and maternal systems, shrinks and disappears, as being- 
no longer necessary. 
OF THE ADDITIONAL MEMBRANES WHICH THE OVUM RECEIVES 
FROM THE UTERUS. 
While the ovum is taking the changes consequent upon 
impregnation, the womb partaking of the general sympathy 
which prevails over the whole uterinesystem, suffers a change 
adapting it for the reception of the ovum. The first appear- 
ance of action in the womb is marked by a greater activity of 
the vessels, a swelling and softness of its substance. While on 
the inner surface there is an exudation, which, being converted 
into a spongy- membrane, is peculiarly adapted for the recep- 
tion and adhesion of the ragged and vascular surface of the 
ovum. 
In this plan we shall be able to observe the relations and 
inflections of the uterine membranes or decidua, as seen and 
described by Dr. Hunter, and of their correctness, my obser- 
vations in dissection leave no doubt in my mind. AA, the 344 
OE THE WOMB. 
'uterus in outline; B, the amnion with the foetus; C, the 
chorion. Nov/ it is observed, upon a careful examination of 
an abortion of the early months, that besides the chorion and 
amnion, there is a spongy membrane of two distinct lamina; 
which invests the chorion. The outermost of these is found 
to surround the whole'ovum, even investing that part which 
has become the placenta by the accumulation of vessels. This 
outer membrane then may be represented by the line DD. It 
is represented as adhering to the surface of the womb, as it 
must do in fact. We observe again, that it is perforated 
where the Fallopian tube enters the womb, that at this part 
it is not formed; so that, according to Dr. Hunter, and the 
preparations which I possess, these'tubes open into its inside. 
Upon dissecting up the outer lamina of the decidua, we find 
that where the placenta commences, it is reflected over the 
surface of the ovum and the shaggy chorion of the ovum, so 
as to be represented by the letters EE. We shall now under- 
stand the distinction betwixt the Decidua Vera DD, and 
the Decidua Reflexa EE. 
It would appear that this membrane is either completely 
formed, or at least the fluid which is to form it, is throw n out 
previous to the descent of the ovum; indeed, so intimate is 
the sympathy betwixt the whole uterine system, that this 
membrane is formed in those cases where the ovum does not 
descend, but constitutes the extra uterine conception. 
Cavity of the UterOi. 
Dr. Hunter supposed, that the ovum passed into the cavity 
of the uterus whilst the coagulable lymph was pouring out by 
the arteries of the uterus, and that it was thus immersed in and 
surrounded by the decidua, for he could not conceive that it 
could gain admission betwixt the lamina of the membrane 
already formed. 
The only other supposition is, that the ovum A, upon its 
descent, gets entangled behind the deciduous membrane B, by OF THE WOMB. 
345 
which means the ovum is not left loose in the cavity of the 
womb, but it is soon attached and surrounded with a mem- 
brane, or vascular web, from which it can immediately draw 
supplies, and by this provision also its adhesion to the supe- 
rior part of the uterus is insured. But as the same action of 
the uterus continues, and, as we must naturally suppose, be 
rather occasioned by the presence of the ovum in its cavity, 
the surface of the uterus at A continues to throw out a coagu- 
lable matter which surrounds that part of the ovum, so that this 
will immediately become its situation. 
A, The Decidua Vera, formed before the descent of the 
ovum. B, the Decidua Rejlexa, formed by the ovum getting 
behind it and pushing it down. C, the efflorescence which 
continued to be poured out, surrounds the upper part of the 
ovum, and which, from its more immediate supply from the 
uterus, will in time form the sole support of the foetus, viz. 
the uterine portion of the placenta. 
OF THE PLACENTA, AND OF THE NUTRITION OF THE FCETUS. 
When the ovum first descends into the uterus, the fleecy 
surface of the chorion establishes a universal adhesion, but no 
sooner is the attachment of the ovum established, than the 
vessels of the foetus which are universally distributed over its 
surface, begin to accumulate to that point from which the 
more abundant supply is obtained. Thus, from the universal 
adhesion, the vessels of the foetus are massed and accumulated 
together, so as to form a thick cake or placenta. This takes 
place upon the same principle that the roots of a plant stretch 
towards the soil best suited to it, or the branches and leaves of 346 
OF THE WOMB. 
a plant grow and spread towards the light- The placenta is 
destined to adhere to the fundus of the womb, and there we 
observe the accumulation of the large vessels of the womb, it 
being equidistant from the several sources of blood ; and to 
this point is the tendency of the vessels of the chorion so 
great, that we sometimes see the vessels of the chord running 
three or lour inches upon the membranes before they reach 
the placenta, evidently showing that the point to which the 
umbilical cord had been originally attached, was not opposite 
to the more vascular part of the womb : but that the vessels 
had to stretch and elongate some way from the insertion be- 
fore they accumulate in form of the placenta, towards that 
part of the uterus where there was the greatest vascularity. 
But the formation of the placenta on the fundus of the 
womb is not constant, although there are many provisions lor 
insuring attachment there. But when it does form low in the 
womb, or on the orifice itself, we then perceive the reason oi 
nature’s solicitous care in preventing it; for it occasions the 
most dangerous floodings from the placenta presenting on the 
approach of labour, and its connections being necessarily torn 
up previous to the delivery of the child. 
The placenta of the advanced stage of gestation is a mass 
formed partly by the accumulations of the vessels of the fetus 
(the trunk of which is the umbilical cord,) and partly of a 
vascular and cellular portion formed by the uterus. On the 
surface attached to the womb, the placenta exhibits deep and 
irregular fissures which divide it into lobes ; but on the inner 
surface is smooth from the investing membranes, but raised 
into irregularities by the numerous and tortuous ramifications 
of the umbilical vessels. When rudely torn or cut into, it ap- 
pears to be a spongy substance, formed in a great part of an 
irregular tissue of vessels. 
In the human subject we find, that the maternal part of the 
placenta is thrown off with the other secundines, and does not 
separate from the fetal part of it. While, in other viviparous 
animals, the monkey excepted, the filamentous extremities of 
the fetal vessels separate from the glandular mass formed by 
the maternal vessels of the uterus. 
T he placentary vessels of the fetus never touch the surface 
of the womb, but communicate with the maternal system 
through the vessels of the womb, which pierce the deciduous 
membrane. Still the question of the precise manner in which 
the vessels of the fetus communicate with those of the mother 
remains undetermined. I conceive that in the early stage the 
deciduous membrane being thrown out by the action of the 
uterine vessels, those of the chorion stretch into it, and absorb OF THE WOMB. 
347 
the nourishment. The decidua is a vascular membrane, but 
it has, at the same time, a peculiar spongy texture. This 
spongy or reticulated structure of lamina of the decidua ceases 
where the placenta is affixed. When we carefully dissect up 
the decidua to the margin of the placenta, it is found to be 
more rigid, white, firm, and thick.* When we examine the 
outside of an entire ovum, we observe that at the place cover- 
ing the placenta, it is corrugated and full of irregular emi- 
nences like the convolutions of the brain, and amongst those 
irregularities many small convoluted arteries may be discern- 
ed, with spots of extravasation and the flat mouths of veins. 
Upon dissecting up this maternal part of the placenta, we find 
U to form the firmest part of it; and by the difference of co- 
lour, as well as by the possibility of tearing it up, or dissecting 
from the mass of vessels of the chorion, we recognise it as 
the decidua. This union, however, betwixt the maternal and 
fcetal parts of the placenta is intimate, and it is impossible to 
determine by dissection with the knife, whether there be in- 
osculations betwixt the maternal and fcetal vessels, or whether 
the nourishment of the foetus is by absorption, nor can we 
distinguish in the first months the cellular intertexture which 
may be observed in the placenta of the full time, as described 
by Mr. Hunter. 
In explanation of this part of our subject, I have purposely 
dissected, and made drawings of the ovum in several stages. 
OF THE LIQUOR AMNII, AS CONDUCING TO THE NOURISHMENT 
OF THE FOETUS. 
Some physiologists, observing the strict analogy which exists 
between the function of the placenta and the lungs of breath- 
ing animals, have conceived, that the liquor amnii is the source 
of nourishment, and that it is taken into the stomach. I be- 
lieve they have conceived some analogy to exist betwixt the 
albumen of the egg and the liquor amnii, which in their minds 
has strengthened this opinion. But there is here no analogy ; 
we have seen, that the embryo of oviparous animals being- 
formed with the yolk in the egg-bed or ovarium, descends 
into the uterus, and there receives the addition of the albumen 
or white. On the other hand we find that the ovum of vivi- 
parous animals is formed in the ovarium; and that the liquor 
amnii being within the membranes of the ovum, must be the 
production of the foetal system. Further, when the ovum has 
* I sneak after dissecting the ovum of the third month. 348 
of the w.omb. 
descended into the womb, and grown to some maturity, we see 
that there is no connection by vessels betwixt the foetus and 
mother but through the placenta; that the liquor amnii is within 
the involving membranes of the foetus, and that consequently 
it must be thrown out by the vessels of the foetal system. 
Thus, to suppose the foetus to be fed by the liquor amnii, would 
be to suppose it to draw resources from its own system, and 
that the vessels poured out a fluid, which is afterwards to be 
taken into the stomach.* But without adducing arguments, 
it is sufficient to say, that foetuses have been brought forth, 
monstrous in their conformation, and without mouths, yet 
well grown. 
Of the placenta as the source of nourishment to the 
fcetus. When we consider the mere speck of the embryo in 
the first weeks, we see that it can have no other source of nou- 
rishment than through the extreme vessels of the chorion, con- 
nected with the short umbilical cord; and we may be con- 
vinced also, that in its progress to maturity, when the general 
connections of the chorion cease, and the placenta is formed, 
the sole supply is through its vessels. Regarding the manner 
of the communication betwixt the vessels of the mother and 
child there are many opinions. The simplest explanation, but 
the furthest from truth is, that the arteries of the womb are 
continued into the veins of the foetal portion of the placenta. 
That on the other hand, the arteries of the foetal system arc 
continued into or inosculate with the veins of the womb ; and 
that thus the blood of the mother’s system is carried by direct 
inosculation. 
Alittle investigation will convince us, that this is a very un- 
likely conjecture. We see the embryo surrounded with its 
vessels, and forming a complete system within itself, descend 
into the womb. We see that the attachment betwixt the sur- 
face of the ovum and the womb, depends on a reciprocal ac- 
tion betwixt them; and when the foetus is feeble, or diseased, 
or when it dies, the uterus immediately separates from it, as 
from a dead part, and there is an abortion. Again, it is not na- 
tural to suppose, that the circulating fluids of the adult are cal- 
culated for the circulation in the embryo, or that the blood of 
the adult is fit for the circulation of the foetus. When we inject 
the vessels of the fcetus, we find the veins and arteries of the 
umbilical cord to inosculate freely with each other, and the 
fluid passes from the arteries to the veins with little extravasa- 
tion or escape of fluid, and such only as may be supposed to 
* A greater absurdity than that of which a foreign author is guilty cannot 
be imagined : because the liquor amnii, or some fluid, is found in the trachea, 
he supposes that the foetus respires, and receives oxygenation from the liquor 
amnii OF THE WOMB. 
349 
pass from torn vessels. Again, the bleeding of the child does 
not draw from the maternal system ; for example, when the 
accoucheur has to perform the operation of embrioulcio, and 
when the arteries of the brain pour out their blood, the woman 
does not suffer, nor is there any danger of hsemorrhagy from 
the cord after the delivery of the child. Again, what does the 
analogy of other animals show us? We may observe, in the 
first place, that probably on account of the peculiar form of 
the womb of woman, and in these circumstances to guard her 
from danger of hsemorrhagy during delivery, it is necessary 
that the placenta should be accumulated towards the fundus 
of the womb. Now, to allow less danger of the separation of 
the secundines from the womb, and consequent abortion, there 
follows a necessity for the human placenta being attached in a 
particular manner: and in place of the maternal part of the 
placenta remaining with the womb, as in other animals, the 
whole mass separates on the delivery of the child. The ne- 
cessity for this firmer attachment of the human placenta, 
causes the connection betwixt the fcetal and the maternal por- 
tions to be very intimate, and the manner of the vascular 
connection by no means easily demonstrated. 
In other animals, however, for example, in those which have 
the small and numerous placenta, or cotyledons, the fcetal and 
maternal portions of the placenta separate easily; the mater- 
nal part being a prominent vascular bed, which is a part of the 
womb, and is not deciduous. Here we find, that the glandular- 
like portion which belongs to the womb may be minutely in- 
jected, and no particle of colour pass into the fcetal part: and 
again, injection shows the foetal portion to be merely composed 
of the fleecy extremities of vessels, which, however minutely 
injected, do not show any inosculations with the maternal ves- 
sels ; in short, here the connection betwixt the extremities of 
the two systems is so very loose, and the filaments so minute, 
and almost like an impalpable mucus, that we can imagine no 
other kind of connection than that the extremities of'the 
umbilical vessels take up by absorption the nutritious matter 
necessary for the system of the child, and that this is secreted 
by the vessels of the womb. 
Investigation in every department of natural history shows 
a similarity and a simplicity in the operations of nature. Com- 
parative anatomy may be brought Avith much advantage in 
illustration of the very obscure laws Avhich guide the functions 
of the parts of generation. When we turn our attention to the 
egg, we find, in the first place, that the vascular system is com- 
plete within itself, and requires no permanent connection with 
the maternal system to invigorate its action. We find that the 350 
or THE WOMB. 
artery which passes out of the umbilical cord of the chick, and 
which is distributed to the membranes of the white, pulsates 
strongly, and carries venous-coloured blood. We find the re- 
turning vein carrying arterial-coloured blood. We find then 
that these vessels must have a double function; they imbibe 
the nourishment from the white, and convey it to the increase 
of the chick ; and they at the same time perform an action 
similar to that of the pulmonary vessels of the adult, seeing 
that they carry out dark-coloured blood, and convey it back 
to the chick, of a bright vermilion colour. Now, I do not 
conceive that this change upon the blood is performed by the 
communication of the atmosphere through the shell, for I see 
no distinction in the colour of the vessels, which are conti- 
guous to the membrane of the shell, and those which are re- 
moved from it by the expanding of the air-cell. Further, we 
find, that there is an intermediate kind of generation in fishes 
which are oviparous, but retain the egg within their womb, 
until the fetus is matured ; here no communication with the 
air or water can be allowed. 
Since we see that the chick in ovo is capable of ministering 
ia every essential particular to its own increase, wherefore 
should we suppose that the fetus of viviparous animals has 
any other more particular connection with the womb of the 
mother?—The difference is in my mind this simply ; the ovum 
of the oviparous animals descending through the convoluted 
and intestinal-like womb of the hen, accumulates a quantity 
of matter around it, which serves every purpose of nutrition 
when the embryo shall be finally separated from the mater- 
nal system ; but in the viviparous animals the ovum descend- 
ing into the womb remains there, and has an incessant supply 
of nutritious fluid, secreted from the vessels of the womb, as it 
is required by the appetency of the fetal system. As in the 
egg, the membranes surrounding the white have the sume ef- 
fect upon the blood, which is afterwards produced by the lungs; 
sohas the placenta of viviparous animals the double function of 
supplying nourishment, and the purifying of their blc/od. The 
umbilical vein carries back pure arterial blood, and the com- 
mon opinion is, that the blood of the fetus coming in contact 
with the blood of the maternal system, receives the principle 
from it, which bestows this quantity of colour, with other ne- 
cessary qualities, of which this of colour is but the sign to our 
observation ; or we may say that the carbon of the fetal blood 
is imbibed by the maternal blood ; and in this way the blood 
of the fetus is purified. It is not necessary to this change on 
the fetal blood, that it should come in immediate contact with 
the maternal blood, for it is possible, that the matter thrown Of THE WOMB. 
351 
-out by the maternal vessels, whilst it is nutritious, has also in 
it, in a condensed and not a gaseous form, that which is es- 
sential to the change of the blood of the fetus from the 
modena colour to bright vermilion. 
OF THE EXTRA-UTERINE CONCEPTION. 
We find some curious facts relating to the action and sym- 
pathy amongst the parts of generation, proved by the cases of 
extra-uterine conception, where nature, baulked and interrupt- 
ed in her usual course of operation, shows unusual resources. 
It would appear, that the ovum, after impregnation, has, in 
some cases, remained attached to its original seat in the ova- 
rium, perhaps owing to some want of due sympathy and syn- 
chronous action of the Fallopian tubes, which should grasp 
and receive the ovum. In other instances the ovum has been 
received into the Fallopian tubes, but either from a want of 
sufficient dilatation and action in them, they have not been 
able to propel it forward, or the ovum, taking upon it that ac- 
tion which is destined to form its connections with the uterus, 
adheres, and is enlarged in the tube, so that it cannot be con- 
veyed down into the womb. 
I am not so fully satisfied of that kind of extra-uterine con- 
ception, where, after impregnation, the ovum has dropt from 
the ovarium, and lies in the cavity of the abdomen amongst 
the viscera. Here it is supposed the vessels of the fleecy cho- 
rion spread, and attach themselves to the surface of the vis- 
, cera. 
These instances of deviation from the natural action of the 
parts after conception prove to us, I think, that from the mo- 
ment of impregnation there is a principle of life and activity 
in the system of vessels of the ovum, and that at a stated pe- 
riod this action becomes such, that the efflorescent vessels of 
the surface of the ovum attach themselves to whatever vascu- 
lar surface they are in contact with. Further, it seems to 
show, that in the womb, and in the deciduous membrane which 
it prepares for the reception of the ovum, there is nothing very 
particularly necessary, and that any vascular surface will take 
upon it the same changes, and being excited probably to some 
peculiarity of action, will in every thing essential supply the 
growth and nourishment of the ovum and fetus. 
It shows us how far the action previous and consequent to 
impregnation is a universal and sympathetic excitement of the 
uterine system ; that the decidua is formed in the cavity of 
the womb, although the ovum does not descend. This points 352 
or THE WOMB. 
out to us how careful nature is, that there shall be a reciprocal 
action in the ovum and womb, so as to insure the adhesion of 
the ovum, and the ready supply of a proper nidus for it, when 
it shall have descended into the cavity of the womb. It in- 
forms us, that the uterus is a spongy and vascular bed, having 
peculiar sympathies which actuate its vessels, and a form of 
vessels adapted to quick acceleration of action so as to grow, 
enlarge, and supply the secundines with nourishment. 
It is not, however, in the mere adhesion and supply afford- 
ed to the foetus, that the peculiar adaptation of the womb for 
the reception of the foetus is shown, but in the provision lor 
the delivery of the child at a regular and stated period. For, 
it is a curious fact, that in the case of extra-uterine foetus on 
the expiration of the nine months, the uterus takes upon it 
that action, and that excitement of its muscularitv which is 
destined to expel the foetus. We find, that at the usual time 
of uterogestation, there are pains excited, and flooding, with 
the discharge of the decidua from the womb, although it con- 
tains no foetus. 
Nay, further, it would appear from the result of several 
cases, that at the expiration of the natural term of uteroges- 
tation, the foetus indicates that it is governed by prescribed 
laws, which render a change necessary, and show that its sys- 
tem is no longer fit to be supplied through the placentary ves- 
sels, and as in the situation of extra-uterine foetus this change 
cannot take place, it dies and becomes with its secundines as 
a load of foreign or dead matter in the belly. This event is 
generally followed by the death of the mother, though some- 
times an abscess has opened and discharged .the foetus, or after 
much suffering, the bones have been discharged by stool, at 
long intervals. 
OF TIIE WOMB AT THE FULL PERIOD OF GESTATION, AND OF 
DELIVERY. 
To complete this view of the female parts of generation, 
it remains only to speak of the state of the parts at the full 
term of nine months, and to observe the process of a natural 
delivery. 
The rapid increase of size of the pregnant womb in the 
short space of nine months, is perhaps the most surprising 
phenomenon of the whole animal economy ; it shows the pow- 
er of a peculiar excitement in calling into action a partial and 
local system of vessels. This state of pregnancy is the fur- 
thest from a state of distention, insomuch, that it is observed 353 
the womb feels peculiarly soft on impregnation, and as if but 
imperfectly filled by the ovum. This soft state is a sign of 
vascular action. We may often observe in the discussion of 
a tumour, that before any change takes place, it swells and 
becomes soft, and this even where the tumour is about to be 
absorbed. 
The fundus of the uterus is the part first enlarged ; and 
afterwards the inferior parts; at length the cervix is obliterated, 
and the uterus, which was originally pyriform, becomes nearly 
oval, and the distention, as we have remarked, is greatest on 
the back part of the womb. In the first months the uterus 
sinks lower in the pelvis, they say from its weight, but the spe- 
cific weight of the uterus is not increased, and on that account 
it should not sink deeper; it is, perhaps, rather from its en- 
largement, and the difficulty with which the fundus makes its 
way among the viscera in the brim of the pelvis. Having 
descended considerably, the os tinea: projects further into the 
vagina, but the fundus continuing to enlarge, at last emerges 
from the circle of the bones, and. then from the conical form 
of the uterus, it sometimes rises suddenly out of the pelvis ; 
now the vagina will be found elongated, and the os tinea 
removed from the point of the finger. 
Now the ligaments of the womb direct it forward, and it 
l'ises close upon the abdominal paries, and before the bowels ; 
in the first pregnancy it rises almost directly up; in subsequent 
pregnancies, from the greater relaxation of the integuments 
and the abdominal muscles, it is allowed to fall more forward; 
about the fourth month of pregnancy, the womb may be felt 
in the abdomen, and rising out of the pelvis; in the fifth month 
the fundus is about half way betwixt the pubes and navel; 
in the seventh, it is about half-way betwixt the navel and 
scorbiculus cordis ; in the eighth, it is at its highest, and to- 
wards the end of the ninth month, it rather subsides. Finally, 
immediately before labour it descends remarkably, and shifts 
into the middle of the pelvis, so as fairly to present the orifice 
of the womb. 
The muscularity of the uterus is inci'easing from the first 
moment of pregnancy. As the uterus increases in thickness 
and is distended, the muscular fibres become more distinct, 
and their power of contraction greater ; but what is very par- 
ticular is the great muscular efforts made by the womb during 
labour by these fibres, which have not till that time felt the 
stimulus to action, or been allowed to contract. 
When the period for the approach of labour is arrived, the 
nature of that viscid secretion which seals up the orifice of the 
womb is altered, it loses its viscidity, and all the parts are re- 
OF THE WOMB. 354 
OF THE WOMB. 
laxed and prepared for the transmission of the head; even 
those rigidities, strictures, or callosities of whatever kind, 
which would seem to promise an absolute obstruction to the 
passage of the child, yield and relax previous to labour. The 
action of the womb is at first feeble, as might be expected, 
and accoucheurs have marked these stages of a natural labour. 
1st. The womb has suffered no diminution of its size; the 
membranes are entire, and, of course, the contractions of the 
womb are feeble, because before it is allowed to make some 
contraction its efforts are not strong. This is a provision for 
the first stage of labour being slow ; by and bye the orifice 
dilating, the membranes with the waters are felt protruding. 
The membranes and rvater is as a soft conical cushion, gently 
dilating the passage; and in this stage there should be no offi- 
cious interference. While the membranes are entire, both the 
mother and child are in perfect safety. 
2d. The orifice continuing to dilate, and the efforts of the 
womb increasing, the membranes burst, and the head of the 
child presses on the orifice ; then the womb is allowed to con- 
tract; this contraction is a stimulus to greater efforts, and in a 
few pains, the head descends into the cavity of the pelvis. 
The orifice is completely retracted, and there is no longer a 
mark of division betwixt the womb and the vagina ; they are 
as one canal. If, however, the membranes are burst too early, 
the labour is not accelerated, but retarded. The orifice is not 
dilated by the soft and elastic membranes ; the head of the 
child presses broad on the orifice, which becomes rigid, and 
perhaps inflamed, its dilatation is slow, and the labour tedious. 
Though from the form of the bones, and particularly by the 
retiring of the sacrum, there is a provision and guard for the 
soft parts of the mother against compression by the head ; yet 
nature intends this stage to be short, for it is the period of 
danger. There is now obstruction of urine and faeces, and 
the vessels ol the parts suffer compression. 
3d. Now the head of the child presenting at the orifice of 
the vagina, forms a third stage ; it is the stage of most ex- 
quisite suffering: ;the head is pushed forward during every 
pain, and recedes again in the absence of pain. An interval 
of rest precedes this stage, at last the pains return, and the 
hard head of the child coming to press on the orifice, and the 
womb coming in close contact with the body of the child, the 
pains are redoubled in strength. The face of the woman, per- 
haps, before pale and flat, becomes red and turgid, the eyes 
gleam, and are inflamed ; the pulse becomes quick and hard; 
and from the exquisite expectation of relief, she looks wildly OF THE WOMB. 
355 
round on her attendants, losing all reason and recollection ; she 
is frantic, with the most agonizing pain to which the human 
frame is subject. Now the occiput of the child begins to pro- 
ject with its wrinkled scalp through the external parts, but 
nature intends that this also should dilate slowly ; the liga- 
ments and os coccygis resist several throes, and direct th<j 
head forward under the pubes ; at last, after several pains, it 
rises with a half turn, and is delivered. 
4th. The fourth stage, is the delivery of the body and shoul- 
ders ; and, 
5th. The fifth stage, is the delivery of the placenta. The 
placenta is expelled by a continuation of the same action of 
the womb, and is part of the natural process. First a flow of 
the liquor amnii and blood follows the child, and the woman 
lies for a time exhausted ; the extreme pain and excitement 
having ceased. The womb generally recovers its powers in 
about twenty minutes, and then there is grinding pain in the 
belly, and the placenta is detached and expelled, or is pushed 
down into the vagina. 
Thus we have sketched, in the most superficial manner, the 
progress of a natural labour, with a view merely to explain the 
general notion of the entire function of the womb, not with 
that minuteness which the accoucheur would look for in treat- 
ing the subject. Let us for an instant, attend to the state of 
the umbilical cord, and the final contraction of the womb. 
I have already observed, that while the membranes are un- 
broken, the child is safe, that is to say, there is no danger ol 
the compression of the umbilical cord ; but when the mem- 
branes have burst, and the waters are evacuated, the cord 
must suffer a degree of compression betwixt the uterus and the 
child, and there is danger that the cord may fall down before 
the head, until the head has decended into the brim; as the 
uterus contracts, and as it were follows the child, the circula- 
tion through the placenta must become somewhat difficult, and 
the usual function corresponding with that of the adult lungs 
impaired. This must be much more the case when the child 
is delivered, and the placenta remains in the contracted womb. 
No doubt nature intends by this, that the function of the pla- 
centa shall be gradually diminished, and not suddenly cut off, 
that the child may feel occasion for the play of the muscles 
of respiration, and that the functions of the lungs may, by de- 
grees, take place of the function of the placenta. When the. 
child is first delivered, the cord pulsates strongly; when the 
child cries, it becomes feeble ; at first, the child has strong and 
irregular catches of the respiratory muscles, but by and bye it 
breathes more regularly, and cries lustilv. At first the breath- 356 
or THE WOMB. 
ing only renders the pulsation of the cord feeble, but presently 
the pulsation becomes so weak that it is felt only near the 
umbilicus, and it ceases when the regular and interrupted 
breathing is established, and the crying ceases. 
The delivery of the child and placenta is followed by a con- 
siderable efflux of blood. But after this there continues a dis- 
charge from the uterus which is called the lochia. It is like 
the exudation of blood from an extensive wound, in as much 
as by the contraction of the vessels from which it flows, it be- 
comes serous in a few days, and ceases gradually like a hse- 
morrhagy. 
This open discharge from the womb after delivery, is no 
doubt a provision against the consequence which would na- 
turally result from the sudden and perfect obstruction and the 
activity of the uterine vessels consequent on delivery. By 
this discharge the activity of the vessels is gradually relieved, 
and as it is a discharge taking place of the active state of the 
womb, so the secretion of the milk in the breasts, and the 
giving of suck, causes the discharge to cease much sooner than 
it would do if the mother were not the nurse. 
OF THE MAMMiE. 
In man and in children of both sexes, there is no mark of 
the breast, but the little cutaneous papilla, or nipple. These, 
tubercles, are, however, surrounded by a zone or disk, of a 
brownish red colour, the areola. 
At puberty, as we have said, the breast of the female be- 
comes protuberant, and those parts which were in miniature, 
and without action, quickly grow into a firm glandular mass. 
The shape, rotundity, and firmness of the gland depends much 
upon the adipose membrane surrounding and intersecting the 
glandular body. 
The glandular part itself is divided into little masses, which 
again consist of small granules. These several subdivisions of 
the glands are closely surrounded by membranes. 
The lactiferous ducts are gathered together from these les- 
ser granules, and unite into 12 or 15 in number of a very con- 
siderable size, as they converge towards the root of the nipple. 
When milk is secreted, the glands are large, a remarkable 
distention of the ducts also takes place, for they are then be- 
come tortuous and varicose, and serve as reservoirs of the milk. 
Where they pass through the nipple, however, they are again 
contracted, and open by small pores upon its surface. The 
nipple is of a spongy and elastic nature, and suffers a disten- OF THE WOMB. 
357 
tion or erection. When the nipple is contracted, the lactife- 
rous ducts must be compressed, and perhaps coiled together, 
so that the milk cannot flow, or flows with difficulty; but by 
the sucking of the child, the nipple is distended, and the 
ducts elongated, so that the milk flows. There open upon 
the areola several superficial or cutaneous glands, which pour 
out a discharge to defend it and the nipple from excoriation. 
Of the arteries, veins, or lymphatics of the mamma;, we 
need not treat here. 
We have many occasions to observe the consent and sym- 
pathy which exist betwixt the womb and the breasts. On 
the first period of the menses, the breasts are much distended. 
In many women at each return of the discharge, a degree of 
swelling and shooting pain is felt in them, and the enlargement 
and shooting pain in the breast, with the darker colour of the 
areola, is marked as the most prominent sign of pregnancy; 
with the ceasing of menstruation, which is the cessation of the 
usual excitement and action of the womb, the breasts contract 
and are absorbed. Any unusual stimulus or irritation in the 
womb, as polypus, or cancers, or even prolapsus and excoria- 
tion, will affect the breasts, causing them to enlarge and be- 
come painful. 
When the function of the parts ceases, they seem to feel the 
want of the usual excitement to correct action, and are apt to 
fall into disease ; so it is at least with the womb and mammas, 
for at that period of life, when the system is no longer able to 
support and give nourishment to a child, and these parts sub- 
side from their usual action, they often become scirrhous or 
cancerous, and terminate existence by a tedious, painful, and 
loathsome disease. 
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CHARACTER OF Dr. THOMAS’S WORK. 
The following extracts, taken from some of the many critical 
notices of Dr. Thomas’s Practice of Physic, will show in what estimation the 
Work is held by practical men both in Great Britain and in the United States. 
From British Journals. 
“ A treatise nearly universal in its object, has been particularly desirable, and Dr. Thomas having 
had opportunities of actually observing the diseases and practice of ilift' rent countries, but especially 
those of hot climates, and being conversant with the writings of our best modern authors and 
teachers, may he considered as well qualified to undo take so important a task. We think that Dr. 
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research, and as a Practical Physician, and that his wo k deserves to stand high in the catalogue of 
this kind of compilation.”—London Medical Ri view. 
“ In compilations of this sort, it is sufficient that, in addition to a clear and methodical arrange- 
ment, due diligence lie employed in collecting from the proper sources, and judgment in discrimi- 
nating between real and pretended discoveries. In these respects, we think the author of the present, 
work has not been deficient. It is a compendium of the existing Doctrines and Practice of Medicine.” 
Medical and Chirurgical Review. 
“ This is a judicious compilation of facts, from the best writers, which may be perused with great 
advantage by students,because ihe different subjects arc trea.ed with brevity and perspicuity. The 
Author has chiefly followed Dr. Culler., both in the classification of diseases, and in his text; but it is 
necessary to add, that Dr Thomas does not prove a servile copyist. He has abridged with judgment, 
has added modern opinions and discoveries, has frequently introduced the result of his own experi- 
ence, and his performance thus becomes an useful Coinjiendiuin of the present Stale of Medical 
Practice.”—Monthly Review. 
“ We have read this Work with great satisfaction, and think it a concise but judicious abstract of 
the Prae.ice of Medicine. 1'he Author’s description of diseases is clear and characteristic; his reme- 
dies appropriate and well chosen. His description of the Yellow Fever is peculiarly accurate.”— 
Critical Review'. 
“ Books of this kind, when properly executed, containing the opinions of the best writers on the 
several diseases, abridged and placed together before the reader, may serve for occasional reference 
to refresh the memory, and save ihe trouble of turning over numerous volumes: they may be useful 
also to students, prior to their entering on a more severe course of study; or to persons whose 
avocations do not permit them to consult more elaborate treatises. The style of Dr. Thomas is clear 
and unaffected, and the arrangement of his Work sensible and convenient.”—British Critic. 
From American Authorities. 
The subjoined paragraph shows in what high estimation “ Thomas’s Practice 
of Physic,” was held by the late Dr. Edward Miller, of New York; who, by an 
extensive practice of many years, united with his superior judgment, was 
peculiarly well qualified to decide on the merits ofaworkon Medicine. 
“ The preceding work is executed with a degree of ability and judgment which reflects much 
honour on the talents of (he author. In Great Britain it stands so high m public estimation as to 
have passed through several editions within a short period ; and is considered by competent judges 
as the most comprehensive and judicious compend of medical practice now extant. The propriety, 
therefore, of presenting an American Edition of a work of such character, calculated to diffuse so 
great a mass of knowledge in so condensed a form, can scarcely be questioned ; and indeed it is to be 
regretted that the task was not earlier undertaken.” 
The slight examination only which we have been able to bestow upon Dr. Thomas's work, leads 
us readily to coincide with the opinion expressed by Dr. Miller, that “ it is executed with a degree 
of ability and judgment which reflects much honour on the talents Of the author.”— American Medi- 
cal and Philosophical Register, Pol. 2. 
Dr. Thomas, in this work, has condensed more facts and more precepts for the management of 
diseases than any modern medical writer we have met with.—New York Medical Repository. Vol. 3, 
third series.