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THE
ANATOMY AND PHYSIOLOGY
                    OF



                  CONTAINING
               THE ANATOMY
 OF THE BONES, MUSCLES, AND JOINTS, AND THE
            HEART AND ARTERIES,
             BY JOHN BELL;
                    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 ANATOMY
         IN THE CHAIR OF DR. HUNTER, &.C &.C.
THE THIRD AMERICAN, FROM THE FOURTH ENGLISH EDITION
IN THREE VOLUMES.
       VOL. III.    >

NEW-YORK:
PRINTED AND SOLD BY COLLINS AND CO. NO. 189, PEARL-STREET.
                   •1817. 
ANNEX
i 
           THE
      ANATOMY
          OF THE
HUMAN BODY.
VOL. III.
        THE ANATOMY
              OF
  THE ORGANS OF THE SENSES,
 THE VISCERA OF THE ABDOMEN,
             AND
THE MALE AND FEMALE PARTS OF
          GENERATION. 
 
CONTENTS
                      OF THE

            THIRD  VOLUME.



                   ANATOMY

                      OF THE

        NERVOUS  SYSTEM, continued.



               OF THE  SENSES.

                 INTRODUCTION, 1.

                      BOOK I.

                 OF  THE  EYE.

                      CHAP. I.

Introductory View of the Principles of Optics       '%
      Simple Idea of the Construction of the Eye   -    12
                     CHAP.  II.
Of the Coats of the Eye         -       .       -    20
      Of the Sclerotic Coat      -       -       .    ;a#
      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
  of Vision          -        -       -       -    36
      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 
vi
CONTENTS.
                       CHAP. VI.
                                                    Page
Of the Humours of the Eye.                             55
      Of the Aqueous Humor    -                      ib.
      The Vitreous Humor      -*>        -        -     58
      Of the Christalline Lens    -        -              ib.
      Of the Capsule of the Lens and Vitreous Humor       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 Ana-
  tomy of the Humors  -        -         -        -      66
                       CHAP.  X.
Of the  Manner in which  the Eye  adapts itself to the
  Distance of Objects          -        -        -     69
                      CHAP. XI.
Of Seeing in general   -        -        -        -     77
      Parallel Motion of the Eyes           -        -     79
      Squinting       -        -         -        -     82
                      CHAP. XII;
Of the Eye-lids, of their Glands, and of the Course of
  the Te.-.rb          -        -         -        -     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 Animals     95
                      CHAP. III.
Description of the Organ of Hearing in particular
  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        -        -    HO 
CONTENTS.
vii
                                              Page
              The Anatomy of the Tympanum        110
              Of the Membrana Tympani        -    112
              Of the Chain of Bones in the Tympanum 113
              Connection and Motion of these Bones   114
              Of the Muscles within the Tympanum    117
              Of the Diseases of the Tympanum      120
        3. Of 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 Diseases of the Internal Ear     -        ■»    137


                    BOOK HI.
OF THE NOSE AND ORGAN OF SMELLING.
Of the Sense of Smelling       -       -        -    140
                    BOOK IV.
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
  Amygdalae         ...       -    148
                    CHAP. IV.
Of the Sense of Tasting        -       -       -    151
                    BOOK V.
  OF THE SKIN, AND SENSE  OF TOUCH.
Of the Skin          -       -       -       -    153
Of the Structure and Growth of the Nails    -       -    155
Of the Hairs          -       -       -       -    156
Rete Mucusom        -       -       -       -    157
Of the True Skin      -       -       -       -    159
Of the Organ of Touch         -       -       -    160
Function of the Skin    -       -       -       -    161
Explanation of the Plates    -       -       -    164 
viii
CONTENTS.
            ANATOMY
               OF THE
VISCERA OF THE  ABDOMEN.
                  INTRODUCTION.
 VIEW OF THE  SYSTEM OF THE VISCERA  AND OF
          THE STRUCTURE  OF GLANDS, 173,
                       CHAP. I.
                                                   Page
 OF the Abdomen in general, and of the Peritoneum       187
                       CHAP. II.
 Of the Viscera of the Abdomen    -        -        -    196
 Of the ffisophagus      -        -        -        -    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 Fluid    -        -        -            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. HI.
 Of the Solid and Glandular Viscera of the Abdomen     236
 Of the Liver   -        -        -        -        -     ib.
 Of the Function of the Liver and of the Secretion of the Bile  250
 Case of Absence of the Vena Port®                      253
 Of the Pancreas        ....    255
 Of the Spleen          -                             258
Opinions regarding  the Use of the Spleen   -        -    260
 Kidney       .....    263
 Minute Structure of the Kidney     -        -        -    2b5
 Ruysch's Doctrine      -                              269
 Bertin's Doctrine       -         -        -        -    271
 Of the Office of the Kidneys       -        -        -    272
 Of the Capsulre Renale?          -        -        -    273 
CONTENTS.                  IX
        ANATOMY
             OF THE

VISCERA OF THE PELVIS.
      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 Pelvis,
  but seated without it        ....    282
    Section 1. Of the Penis and Urethra     -     -     ib.
           2. Of the Testes       -      -      -    288

     OF THE FEMALE 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 Mamma;  -            -           356
Vol m.
B 
EXPLANATION
                            OF

             THE   PLATES.


                       PLATE XX.

 JL HIS plate represents an ideal  section of the abdomen, and
the cut edge of the peritoneum is represented by the white line.
a. 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 la-
     mina of the ligament 2, over its surface 3, forming the peri-
     toneal coat of this viscus.
4. Marks the peritoneum reflected from the liver upon  the  dia-
     phragm.
5. Here the  peritoneum is reflected off from the spine, to form
     one of the lamina of  the mesentery.
6. The peritoneal coat of the intestine, which we can trace round
     the circle  of the gut until it unites again with the mesen-
     tery.
7 7. The peritoneum, forming the lower lamina of the mesen-
     tery.
 8. The peritoneum at that part where it is reflected, and covers
     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 see the 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 shews, that it forms one continuous
     sac,  and that the intestines and the liver are equally on the
     outside  of this membrane with  the kidney.
                  Explanation of Plate JiXI.
   This plate represents the epidydimis and testicle,  injected with
  quicksilver, artd dissected.
  A.  The body of the testicle wilh the tunica albuginea dissected off.
  BB. The seminal vessels  in the body of the testicle or tubuh
     testis.*

   * Where the tubuli are emerging to form tlie  rete vasculoturo, or rete testis, they are
  caHed the vasa recto. 
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            EXPLANATION  OP  THE  PLATES.           XI

C. The rete testis formed by the union of the vessels B. B.
d.  The vas a efferentia, which as they  proceed  from the testi-
    cle, are convoluted in a conical figure, and are called the vas-
    cular conls.
ee. 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 XXII.
  This  Plate represents the prostate gland, vesiculae seminales,
and lower part of the  bladder, the  parts being previously harden-
ed in spirits, the vesicular 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.
b. The prostate gland is here cut into and dissected, in following
     the ducts of  the vesiculae.
c. The extremities of the ducts common  to the vesiculae seminales
     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 termination.
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.
1. The RIGHT URETER.
                 Explanation of Plate  XXIII.
   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.
 c c. The substance of  the  prostate gland, which  is  cut through ;
      its thickness, texture, and the manner  in which it surrounds
      the beginning of the urethra, will be  understood from  this
      plate.
 d. The urethra laid open.
 f.  The verumontanum, or caput galinaginis.
 g o.  The points of feathers put into the  openings of the vesiculae
      seminales and vasa deferentia.
   N. B.  Round these ducts, on the surface of the  verumontanum,
 and in that part of the urethra which is surrounded by the prostate
 gland, innumerable  mucous ducts maybe observed: into some
 of these  small bristles are introduced.
                  Explanation of Plate XXIV.
   A view of the  penis, vesiculae seminales,  and prostate gland.

                  Explanation of Plate XXV.
                             Fig. 1.
   An ovum in a very early stage,  representing  the shaggy surface
 of the true chorion. 
 Xli           EXPLANATION OF THE  PLATES.

                            Fig. 2.
   We may see here the foetus in a very early stage contained ill
 the transparent amnion, and,  attached  to the outside of the am-
 nion, 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 Fostus hung by the Umbilical  Cord.

                Explanation of Plate XXVI.

   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 decidua in a
 more advanced state;
 a. A thread passed through the  more solid placentary mass sus-
     pending the whole.
 b b. The decidua, having a peculiar retieulated appearance.
 c c.  Shreds of the decidua, where it has burst in the delivery.
 d. The decidua reflexa, through which also the proper mem-
     branes 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  pla-
     centa.
               Explanation  of Plate XXVII.

  We have here presented a view of a section of the same con-
 ception.
 a. The decidua.
 b b.  The cut edge of the decidua, which will be seen to surround
     the whole ovum, and particularly it may be observed to form
     on the upper part  a distinct lamina from the placenta f.
 c c  The decidua.
 d. The decidua reflexa.
 f. The placenta already formed by the accumulated vessels of
     the chorion.
o. The chorion towards the lower part of the  womb; here, it
     may be observed, the fleecy vessels have disappeared.
h. The AMNION.
i. The umbilical cord twisted three times around  the neck of the
     foetus. 
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                      THE

             A NJ TO M Y

                       OF


THE  NERVOUS  SYSTEM.

                   GONTINUEiJ.
*
                OF THE SENSES.

                       INTRODUCTION.


  1 HE 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 hu-
 man body, the physiology of vegetables, or the phenomena 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 enquiries; a
line which no industry or ingenuity can enable him to pass*. We
  vol. III.                    A 
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 phaenomena; yet
we 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 Ave perceive the objects of the senses, in the same
language, and by reference to the came notions, which 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 idea^
in Janguage 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 explana-
tion  can we give of theories, which suppose the nerves  to be
tubes carrying animal spirits, or containing an elastic ether; or
which represent them as vibrating cords, 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
inonstrous 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 expert
went 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 of 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 sen-
 ses 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 encreased 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 to 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 encreased, because there is no intrusion in the objects
of the outward senses; and the  deaf or blind receive some
compensation for their loss in the encreased powers which are 
4                   OF THE SENSES.
acquired by a more frequent and undisturbed use of the sen-
ses which remain,  and a keener  attention to the sensations
which they present.  On the other hand, when we are undei
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 health,  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  falsely 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 in-
ternal sensation ; and the same feeling will be experienced if the
 eyes be shut.  For example,  when  we turn quickly round on
our heel until we become giddy, it would  appear that there is 
OF THE SENSES.
5
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
ontward 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 exci-
ted 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, See. 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 feeling 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 or-
gans.  To such disordered transmission of the irritation of the
internal parts we  have to attribute the extravagant and ludi-
crous 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 intro-
ductory view of the nervous system) we have no feeling nor
consciousness, and over which the will has no  power.  But al-
though in the healthy state of  the  economy there is no imme-
diate route  by  which any sensation from these organs can be
transmitted to excite a mental perception, it may happen, that,
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 sensation 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 ofthe
 present, as the  senses  are in part awake;  some  one train of
 ideas is present to the mind j 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 hcemorrhagy and evacua-
 tions, by lessening the velocity of the circulation;  and cold, by
 lessening the  sensibility; induce sleep.  Again,  compression
 of the returning blood from the head, by giving it a  slow lan-
 guid motion, and by depriving the vessels of their freedom of
 action, also conduces to sleep ; because, as formerly remarked,
 the powers and faculties of the brain must be renovated 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 mus-
 cles, and an abatement of the vital motions ensues •  the quies-
 cent state of the muscles brings back the blood to the heart,
 with a slow, regular,  and calm progression ; the heart is re-
 stored to its slow and equable pulsation;  the  breathing be-
 comes slower;  and  the wasted  strength of the system is re-
 cruited.
  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 vital  and voluntary mo-
 tions.  The vital actions,  which are calm,  slow, and equable,
 during natural sleep, become oppressed ; the sensibility, which
is gradually diminished  upon the approach,of sleep, but al-
ways capable of being roused by the senses, becomes quite op-
pressed ; 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.
/
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 awake ;
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, which depends on the  due balance of mem-
ory and invagination, is lost.  In fever, the delirium is transit-
ory ;  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
receiv8|l opinions in  an elementary  book, I would say that
tiiere 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.


  J-iIGHT 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
  source.  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 phaenomena 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 spectum produced by making a ray delight  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

  t There is afact "?•* a ,ittle. extraortUnaiy regarding the emanation of rays from the tan
and which has been discovered in the present day, viz. that there are invisible rays, eivine
heat but no light, which  are less refractable than the coloured rays;  and that all ravs in
proportion to their refrangibility, have less power of producing heat.  See Hersphel  n»
♦fte invisible rays of light. Phys. Trans.  1800, part ii. p. 284.
^ 
                       OF  THE EYE.                      9

 is  presented,  but that mixed li§bt  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 me-
 dium to another perpendicularly into the surfaces, its  original
 direction is  not changed.  If the ray passing from the air en-
 ters 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 whieh, 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 prefect whiteness.
 We might suspect that the  beams of light were homogenous,
 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
 different colours, for minium will appear yellow, green,  blue,
 Sic. according to the colour of the  ray of light directed up-
 on it.*"

  * It is found, that the coloured rays have not all the same power of illuminating objects;
the orange ray possesses this property more than the red ; the vellow more than the orange,
&c.; and the maximum of illumination lies in the brightek yellow or palest green ; no/ do
the several rays equally affect the thermometer.  See Hmvchel's Kxp. Pliys. Trans. 1800.
p. ii. p. 2bb.
  VOL. III.                    R 
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.
Fig.l.                         m0?2.
  Thus the ray A,  fig.  i., proceeding from the object,* is •
refracted upon  entering the  mass of glass  in the direction B.
having a tendency towards the perpendicular line.  By thi*
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
to 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 off 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. 3.
Fuf.4.
 A.          4-
^WliliH?-^:^'-*""""
  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  sur-
face 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
very distinctly upon the opposed
Fi#. 5.
 
12
OF  HIE EYE.
surface, but  inverted ;  because the rays coming  from the
point a fig. 5., converge  at c, and those from the point b at ».
  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 circumference into the sphere of vision than could have
been done, had the larger sphere of the eye-ball 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.                   r.. „
                            Fig.G.
Aipieous Ttivmar
 Vitreous
humor■.—.
 
OF  THE EYE.
IS
  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 the 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  pupiJ.   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  bottom 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   /"iT" e
colours, as well as the most  / wV
correct image of  the object I    1M/|
presented to the eye.          \  J[Juy
  If the  lucid  anterior part    fN^
of the eye  be formed too pro-     \hh
minent, or if the  lens of the      |||
eye  have too great a degree      \W
of convexity, or, lastly,  if the ^J-7\  lyy.
size of the  ball of the eye, and     I MA
the diameter of  the  vitreous     J/M
humour in the axis of the eye    ll//A|
be  unusually great, then the    l///\|
person does not see distinctly;    Uj  \
because the powers of the hu-    ||f.'  \l
mours,  in  concentrating  the    f   |
rays of light, are too  great,    w    1
and the image of the object is   f     '
not formed accurately on the   ~f£>—3
■.etina, but  before it. Thus, in  fig. 7., the convexity  of the
 
14
OF  THE  EYE.
cornea, the lucid anterior part of the eye, or the focal powers
of the  lens, being toe 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 after 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 the 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 &  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-sigrjted
person peers through  his eyelids, it  makes the rays impinge
accurately upon the retina.*
   The effect of  old age, is gradually to reduce the eye  to a

  * 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 inflammation.  Dr. Brings mentions
the case of an old man,  who had long used spectacles, becoming suddenly short sighted by
catching cold, and he was afterwards enabled to read the smallest print without glasses.  In
general, however, 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 defect to some par
ficular occurrence. 
OF  THE EYE.
15
Fig.Q.
 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, io 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  di-
 ameter  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, 
16
OF  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
 imperfect 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 Aire'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 ^^Vo- 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 of 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 faintly, 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 im-
age 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. 2*T 
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 encreased 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,
 that in the progress  of rays of light,  there is an alternation  of

  * 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 very 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 into the eye, and this deficiency
 ■nust be supplied.
VOL. III.
c 
18
OF  THE EYE.
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 i>, and bdf,
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 i>, as the  refract-
ing surface b a d 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 focus 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-
       but reflected off towards
    but  again the  ray a  n being advanced  farther from  its
source,it will impinge upon the  surface  b d, during  its dispo-
sition ti> 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 f, the reflected  rays of light  will have left
spaces dark where they would have  fallen by refraction, and,
consequently, distinct luminous  circles  will  be thrown on the
cus
c
 
OF  THE  EYE.
19
 plain :  again, if the plain surface be opposed to the rays, after
 they have formed ther 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  f c h.
   How  the changeable
 state of the rays produ-
 ces the  indistinctness of
 the  near-sighted  eye,
 may be understood from
 this  (11.)  diagram.—
 When  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 i>.   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 w&y 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 experien-
 ces a confused outline of the object, which becomes surrounded
 with several rings or false outlines.*

  * By JUs of easy transition, it wa3 not meant by Sir Isaac Newton that the rays must ne-
cessarily 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 wan
it meant that, during its Jit of easy reflection, it was absolutely incapable of being transmit-
ted, but only more readily reflected than transmitted.
 
(20)
                       CHAP. II.

               OF THE COATS  OF THE  EYE.
r ii
 1 HE 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 sclerotica, the choroides,
the retina.
  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 tamed 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, Ruyscb, &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 eye ball.  Upon
the forepart 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 forepart of  it is split into laminae, betwixt
which there are interposed thin plates of bone,* while in fishes
it is in part cartilaginousf, 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
lamineej;  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 re-
lation 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
coat resists  pressure* and the progress of disease  from without,

  * Cuvier, vol. i. p. 367.
  •*• MorgBgni Epist. An. xvi. 40.  Cuvier, 383.
  t Ruysch, Zinn.
  § It may he-w^ll, ;,, this place, to mention the opinions of the chief supporter of that
scheme of the coots oT the eye, which derives them all from the investing membranes of the
brain and oulie nerve.  M. le Cat, in his Traile* des Hens, describes them thus:—When the
optic nerve hus enteiwl the orbit, the dura  mater which  surrounds it, splits into two lami-
na? ; 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.  Thia
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 ante-
riorly, and forms the iris and ciliary processes.  The internal  medullary part of the optic
nerve forms the retina.  Finally, " L'ceil est tres evidemment Pextremits nerveuse epanouie
" boursouflee en bouton creux & plein de liqueurs," p. 158.  See also Bonn Sandifort The
s;iur. de continuatione membrana\ 
22           OF  THE  COATS  OF THE EYE.
it resists the swelling of the parts within when they become dis-
eased, and gives the greatest torture.
  Of what importance the entireness of the coats, and the uni
form  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 transparency.   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.   Steno observed, and Petit confirmed,
the fact,*J that the pores on the surface of the cornea exuded
the fluid which fills the cells of the cornea ; and  that, after the
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. ||
This moisture becomes dull and clammy on the approach of
death, and forms sometimes a pelicle  over the cornea.   The
laxity  with  which the lamina? 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 scissars.  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 of the
knife is very  apt to give a wrong direction  to  the incision-,
and, indeed, this occurred to me  in my first operation.

  * " Cornu modo, dura, & cornu instar in laminas dividareqae potest." VesaliiK.
  | Substantia spongiosa  Valsalva.
  : See also Hovius, p. 82.              ' Z'nn 
              OF 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
 within it, and phlyctaenae are seen  on its surface ;  and in great
 inflammation  of the eye, the  cornea appears red ; which, he
 supposed, must be produced by the same cause, which makes
 the albuginea red, viz. the enlargement of its vessels, and the
 circulation of red blood.   But we must not imagine, he con-
 tinues, 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 foetus ;  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 mi-
nutely injected, as well as the  internal vessels of the eye, 1 had
resolved carefully to examine the structure of the cornea;  and
after a long maceration, in which it had greatly swelled, I ob-

  * This, within these two years, has been claimed as a discovery. I fear that this must be
 considered as the capsule of the aqueous humour, long since described.
  + 1 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 «
pieeeof iron, when it was only the consequence oftbeinjurv. 
24
OF  THE COATS OF THE  EYE.
served 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 profu-
sion, large, and perfectly pellucid:  they are large towards the
middle of the cornea, and diminish towards the margin. Their
free communication formed a net-work deep in the thickened
substance of the cornea.   The size, perfect pellucidness, and
intimate connection of these vessels, might perhaps 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 jj» entirely lost; it  is extended into a reticulated membrane
whiohilhyis 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 ittto consist of two
layers of cellular tissue; and it has upon its inner surface a pig-
ment, which being sometimes firm, might be taken for a mem-
brane.   It was Ruysch who observed this division of the cho-
roid coat into two laminae;  and the inner one his son called
the tunica  Ruyschiana :  but of these hereafter.
  Those anatomists who supposed  the scletoric 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 tu-
nica arachnoides, and the  other of the pia mater;  but this
account of these membranes has no support from observation.

  * Pterygioi, is a disease of the conjunctiva, but which resembles a membrane extended
over the cornea from the canthus. Pannus, is a disease of the same kind, but covering the
cornea as with a white opaque membrane.
  ■*■ Staphyloma uvea, viz. a protrusion and opacity of the cornea : which, from the los^
of transparency and the general appearance of the tumour, is supposed to resemble a grape. 
,. OF THE  COATS  OF  THE EYE.
25
Betwixt the pia mater and choroid  coat  there  is no resem-
blance ; the latter we shall findioaded with vessels: but these
vessels are peculiar, and minister to a secreting surface.   The
pia mater in the brain, and optio 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 expanded
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 kuown 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 *f 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 J^y^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 was not -single in brutes ; he
asserts, also, that Franciscus Sylvius and Guenellonius bad de-
monstrated the  double  laminae  of  this  membrane before
Ruysch. ||   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.
  t Ruysch. Epist. Anat. xiii.              t Albini Annqt. Acad. lib. vii. cap. iv.
                   || Morgagni Epiflt. Anat.  ivii. 3.
   VOL.  III.                    D 
iiO            Oi  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 very 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 nigrum 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 of
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 of
 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 circula-

   K" Quod ad usum tunicse Ruyschianae attinet crediderim hanc tunicam inter ceteros usus
 esse destinatam,  non solum ad robur choroidae, verum etiam ut a sanguinis arteriosi majori
 copia  requesitus calor tribus humoribus natura frigidis conciliaretur.  Ruys. Respons. ad
 Christ.  Wedelium, p. 14.
   f I cannot  conceive how this matter should be confounded with the tapetum 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 Acade-
 micians, in their account of the dissection of a lioness.  "• The membrane 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.  11 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  explanation of tlus, I suppose, will be found
 in Morg. Epist. An. xvii. 3. 
OF  THE COATS OF THE  EYE.
21
ting 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 laminae :  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.
                   ANNTJLUS LIGAMENTOSUS.

  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
tunicae choroidiae.
        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 plica? 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 plicae,

  * As the pigmentum nigrum is a secretion, we shall not be surprized to find it become de-
ficient 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,
ind throws out the beams like a cat's eye.  See Med. Obser. and Enquiries, vol. ui. 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 signatus, 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 p4fe|
of the retina, formed by the impression  of the ciliary proces-
ses, Dr. Monro has called the ciliary  processes of the retina ;
but, for my part,  1  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.J This it is necessary to remark, since I
have seen students confound this mark with the ciliary proces-

  * Fascie vii. icon. ocul.
  ■*• 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.
  t See Morgagni Epist. Anat. xvii. n. 13 .and Ruysch also," NonnuNi pro processu ciliari
agnoscunt pullas pigmeoti nigri relkjuias, membranula? tenuissima?humoris cristallmi & vitrei,
A. quasi fibres mentientes,  oculo sc. aperto, humoribusque exemprie ; ha? aubem nil sunt ni«
avulsae particulae  pigment! nigri."  Rnysch. Thes. An. ii. Ass, 1. No. xv. 
OF  THE  COATS  OF  THE EVE.
ses 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 chotoid  coat; but, of theft  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 retina, 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 [Icones oculi humani\ describes the retina as
spontaneously falling off and separating  from the exterior cir-
cle of the corona ciliaris.   But he also has mistaken the ner-
vous 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 Goats 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 op-
tic nerve and retina, this slender  hold which the ciliary pro-
cesses take of the expanded retina, is the only attachment be-
twixt 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 name.J   Fal-
lopius  and Morgagni^s use the  term  corpus  ciliare for the

  * 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.
  X " JNeque mihi ullum occurrit nomen quod ipsi aptius indain quam tunicas: aut si voles,
" iutcrstitii vol scepliiuter vitreum humorem& cum quem albugineum muicubamus reyvi'.i."
Vesal. voL i. p. 558.
  i Epist. Anat. xvii. 11. 
30
OF THE  COATS OF  THE  EYE
whole circle of the processes, and in the same sense that I have
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.   Rfiysch 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 anulum 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 cilia-
ry processes " rayon ciliares," and  the root of the corona ci-
liaris and iris, " plexus ciliaris."
*«»——
                          CHAP. III.

                         OF THE IRIS.


 J. HE ins 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 esseconsiderandum tan-
quam musculum ad pupilhe et humoris cristallini motum destinatum, totumqoe hoc nego-
i-ium j/erfici a processu ciliari ut et a circulo musculari postezius in  oonfinio pupillae sito."
Theg. Anat h. xv. See also the explanation of 6g. iv. of this Thesaurus, where we have
'• Iris enim est fades exterior, processus Eg. ciliaris facies interior."
  f Winslow and Haller, and most of the old anatomists, call this uvea : by which they mean
10 imply that it is a part of the choroides.   See Ophthalmagraplua Authore G. Briggs, Can-
tab. 1676; but most of the modern  anatomists follow Zinn and Lieutaod in calling it iris -
 hough Lieutaud and others called the anterior surface only iris, while they still continued to
.all 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 of a raisin: and
'he wo"J i:is is borrowed, I yip;«se,  from tlie varied colours- ef the rainbow 
OF  THE IRIS.
Si
tracting and relaxing, holds a controul over the quantity of light
transmitted to the bottom of the eye.  For by the extension
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 connec-
ted with the sensation of the retina; by which means, in  dis-
ease 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 lamina: 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 the first place, because I have found
it fall out a perfect circle by maceration;  secondly, becau§e it
has no  resemblance  in structure  to the  choroid coat; and,
chiefly, as by its power of contracting, it shows a  widely differ-
ent 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
fibres.
  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 brillancy
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 bazel-coloured iris is owing to the greater degree of
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 somr
measure, indebted to the circulation of the blood, we may ex- 
32.                  OF  THE 1IUS.

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.
         OB'  THE MUSCULAR FIBRES  OF THE IRIS.

  [t 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 pupil: he observed also, the cir-
cular or orbicular fibres which run round the margin of the pupil.
Winslow says, that between the two lamina? 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 ra-
diated ; 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 of
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 suc-
cessful in this investigation.*  Wrisberg also affirms, that no
muscular fibres could be seen in the iris of the ox.  Dr. Mon-
ro, on  the other hand, adheres to the opinion of the muscu-
larity 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 ex-
citement of the iris.  The retina is in a  peculiar manner sus-
ceptible 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 ex-
panded nerve of the other senses.
  That the iris is to be affected only through the sensation of
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 Ziun, p. 89 and 90.  Morgagni Epist. Anat. xvii *> 4.  Haller and Ferrein attribute
th« motion of the iris to an afflux of humours in its vessels 
OF THE  IRIS.
33
 the needle without its showing any sign of being irritated; nay,
 what was too a convincing 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 way, 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 with 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 was 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 lig-
 amentum ciliare from without.   These  arteries approach the
 root of the iris at four opposite points, and  branching widely

  * This fact destroys the hypothesis of M. Mery, of the Royal Acad, of Sciences, that the
straight fibres of the iris are little qayernous bodies, and that the action of the light upon the
retina swelled and elongated them so as to cause the diminution of the si2e of the pupil; for
by this cut, they must nave fallen from their erected state, and  contracted so as  to have dila-
ted the pupil. See Acad. Roy. de Sc. 1704, Mem. p, 261.
  f When a cat is rou-cd to attention, as by the scratubing of a mouse, it dilates the pupil,
which allows a stronger impression on the bottom of tht eve: nay, whenever puss struggles
violently to get loose, the pupil dilates, which may sufficiently account for M. Meiy's cat
having her pupil dilated when he plunged her under the water.  See Acad. Roy. des Sc.
 1704, Mem. p. 2G1.
   VOL. III.                   E 
34
CHOROID  COAT AND  IRIS.
from a vascular circle round the root of the iris, viz. the larget'
circle of the iris.  From  this circle blanches 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 forepart 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.!   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
eye-ball, is in  danger of pressing  through and tearing  the  iris.
The  best  operators have been in  the custom of shutting the
eye-lids 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 is protruded,
 by the action  of the muscles of the eye.
   * See Ruysch. Epist. Anat. Prob. xiii. p. 31.
   f Dr. Monro, in treating of this subject, mentions his having seen a net-work of vessels
 covered with paint darker than that of the irb, and extended from the iris upon the surface4
 of the lens; and, in another instance, a net-work of filaments passing quite across the nunil
 oee tns Dissertations, p. 108.                                     r ' •' 
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 ex-
traction 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 fin-
gers.   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
the escape of the lens, I have seen, in consequence  of a hesi-
tating  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 con-
tinuity 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.
The margin of the 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, without  being entirely
displaced ; and a great part of the vitreous humour was allow?
ed to escape.*
               * See further, Operative Surgery, by C. Bell, 
3fj
OF  THE RETINA.
                        CHAP. IV.

 OF THE RETINA, AND  DIGRESSION  CONCERNING  THE  SEAT
                        OF  VISION.


 X HE term retina has, in a  modern publication, been object-
 ed 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 re-
 " tina cum arteriolae ceracea materia sunt rep!etae."f
   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 scle-
 rotic 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 o( 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

 * Dr. Monro's  4to. Treatises.
 f Ruysch. Epist. Anat. xiii. p. 14.   Quamobrem servare adliuc retina', appellationem si
Hon ex hbrarum ut certe ex vasorum implacatione, &c.  Morgagni Epist. Anat. xvii. \ 43. 
OF  THE  RETLN'A.
• i7
 iiear to the eye, the open mouth of this small artery may be
 seen ;  but if we make our section some way removed from the
 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 lhu3
 cut; (or perhaps it was the open  mouth of the  artery itself,)
 was observed  by the ancients, and by  them called the poms
 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  crirrosa, and the delicate fasciculi of  the
 optic nerve, are  shewn 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 rctinae.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 it.J
   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  vessel?.
 When the retina is macerated for a considerable time, the pulp
 of the nerve can be washed away,  and there remains only  the

  * Porumopticum Herophilus et omnis ab ea antiquitas dixit, foramen nempequod in dissec
 to nervode vacua arteria superest.  Hall. Arter. Ocul. Hist. p. 42.  De Vasis Nervi  Opti-
ci vide Ruysch.  Epist. Anat xiii. tab. xvi. Albinus Acad. Anat. lib. vii. c. vii.
  f Zinn deoculo humanop. 106.  Com. Reg. Soc. Scient. trotting, loc.  cit.  About 30
foramina have been observed in the lamina cribrosa. See Haller Fasc. de Arter. Ocu!i, p. 42.
  t Zmn.  " At  the place which answers to the insertion of the optic nerve, \vc observe a
" small deprc^ion, in which lies a sort of medullary button terminating in. a point." Wins-
low, p. 78. 
^3
OF THE  RETINA.
 reticulated and delicate membrane which supports the vessels
 that nourish it.   But 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 retinae.   Of this  preparation I have given
 an engraving, to show how  plentifully  this organ is supplied
 with red blood; from which circumstance we may  learn  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 impinge.f  The vessels of the retina run upon thje sur-
 face contiguous to the  vitreous humour.J   The arteria centra-
 lis retinas 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. ||  Cor-
 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

  * Posse vere Medullarem retinae laminam removeri ut vasculosura rete membranae figuram
 retineat, alteramque ab altera integram detrahi ultra hominum artem positum esse videtur
 nee ulli unquam contigisse legere me memini, etsi, deleta macerendo medulla, rete vasculo-
 sum laminam peculiarem referre videatur.  Ex quibus omnibus ehcio retinam esse tunicam
 simplicem, ex cellulosa conflatam: que vascula et substantiam medullarem sustinet etsi duas
 diversas ostendat facies alteram vasculosam interiorem, alteram medullarem exteriorem."
 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, torn. ii. p. 419.
  The opacity of the outer surface of the retina prevents the vascularity from being apparent.
 Albums, 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 le-
 " vissimeque deradens, mox conspicia vasa impleta multa qua? sub  medulla cujus nimirmo
 " portionem deraseram latuerant" Albin. An. Acad. lib. iii. cap. xiv.
  J Dr. Monro has these words, expressive of an opposite opinion: " The whole appears to
 be composed of an unifonn pulpy matter, on the outer side of which chiefly vessels are dis-
 persed, 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. xvii. n. 44. nor do they always pierce the centre
of the nerve exactly. Morgagni.
  || " Iteratis perscnitiniis reperio oculis armatis arteriolarum extrema tam esse numerosa &
tarn arete sibi invicem et intricate annexa ut peculiarem representent membrannlam ex arter
riolanira extremisconstitutam, cui connectetur dictameduliosa substantia."  Ruysch. Epist.
Ana*,  xiii. p. J.\ 
OF  THE RETINA.
39
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 conceive  (with Albinus, M. Ferrein, and others) to consist
of two distinct parts, viz. the medulla of the nerve, and a pel-
lucid membrane supporting it; but, however reasonable this
conclusion is, I cannot  believe that these portions  are  to be
separated by dissection.  It is by most  anatomists  believed,
that the retina passes forward betwixt 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 t interchange and
mingling of fibres, we  may safely say, that  the membrane of
the  retina is continued  over the lens, and forms part of its cap-
 sule.  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 per-
fectly 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 particularly 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 off the sclerotic and choroid coats of the eye,
 by dissecting  them round the insertion of the optic nerve, and
 fold them back, carefully preserving the retina;  and when we
 have taken away the ciliary processes from  their adhesion to

   * Many anatomists, Winslow, Cassobohm, Ferrein, Lieutaud, and Haller, 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 Mor
 i^agni Ejiist. Anat. xvii. 47. and Zinn, 114. 
40
OF  THE RKT1NA.
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 opaq-tfe pulpy nervous matter,
but tiie  coats of the lens are  transparent, yet continuous with
the arachnoid portidn of the retina.   When these parts of the
eye  are thus dissected, they  iiang all  together 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 olny 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 insula-
ted 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 hu-
mours 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:—
gi 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 op-
tic nerve of my eye, and to find the consequence thereof, I
made this experiment.   I fastened  on an obsctirte'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 e,nd 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 ray right eye fixed and
very steady upon the same, and being about ten feet distant,
the second paper totally disappeard." *
  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. Marriotte, upon 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
contracted in a  more intense light:  now, says he, as the iris 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.   If  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. Picque' asserts, that very luminous objects make
a faint impression on the centre of theoptic nerve. P> t Dr. Priestlvgayp, that a candle makes
no impression on that part of his rye
   VOL. ill.                  F 
42
OF THE  RETINA.
it seems that it should be found where evdr 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
shbuld 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 6^ the black colour of the1 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 metallic
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, by
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 deli-
cate 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
surface for covering the  image; and that its transparency would
cause a partial dispersion, which would produce a confusion in
vision.f
   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.

  * Against this hypothesis, the size of the insensible spot was urged by Marriotte. Ber-
nouilli calculated that ,this spot is acircle, 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.    '-•:"■
  t 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
teach s thnt 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 im-
pression on the papilla? of the tongue. 
OF  THE RETINA.
4&
It is demonstrated that the inner surface of the retina is a web
of membrane conveying vessels, and thajt 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 pos-
terior  surface  peculiarly adapted to  receive  the  impres-
sion 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 poste-
rior surface upon which  the rays can impinge.  The doubts
regarding the cause of this spot giving no sensation, have ari-
sen from the  idea, that the internal 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 strongly 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 evident, 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  impres-
sion 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- 
*
44                   OF  THE  RETINA.

encing the retina, will cause  the sensation of light  or fire be-
fore the eye*   Because  here,  or in its corresponding part of
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 to-
tal blindness,  whHe  the cornea and  humours of the eye re-
main pellucid,  is called  amaurosis.   It is, in general,  to be
considered as  a  paralytic affection.    Amaurosis! has  been
found to follow strokes on the head ; concussion and compres-
sion of the brain ; blood effused within the scull;  or  tumours
pressing on the nerve or brain.J  An amaurosis spasmodica has
been enumerated by authors.   This kind of blindness has been
supposed to arise in consequence of  the stricture of the optie
nerve by the origins of the recti muscles ;>  as far  as  I have ob-
served,  no action of these  muscle's 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 hall
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 eye,  by increased secre-
tion of the humours, destroys the sensibility of the retina.   In
the hydrophtbalmia 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.^

  * Light from pressure oo the eye. See Cartesius, cap. ix. lib. de Meteor, and the  ophthal-
mo-graphia of Briggs, cornea.                         ,
  f AM.irBQSis; gotta serena ; cataracta mora ; which last name is from the blackness
of the pupil in consequence of the transparency of the lens.
  X "Ipse yidi his in puerulis scrophulosis amaurosin, etiam subito ingruentum ; secto cada-
vere inveni glandulam strumosani nervis opticis iucumbentem." Sauvages Nosol.   From
many observations, we find that tumours andfextravasations, which must compress gradually,
do yet produce an instantaneous effect.
  In Bonetus, * we have many cases of blindness from abcess in the anterior part of the
brain ; from fluid on the surface, and in the ventricles  ; from steatomatous tumours ; from
coaguhim 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 displace-
ment and consequent elongation of die optic nerve, by an encysted tumour in the orbit, with
gradual recovery after operations. "See Med. Ob. and Inquir. vol.iv. p. 371.
  * De OcuL Affectibus, Ob. 2.
  $ To complete such a case, we  nay 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 luxatioa or displacement of the eye, by
tumours, causes "Jblindneas, by extending the optic nerve or compressing the eye-ball aw*
consequently the retina. 
OF THE  RETINA.
45
  The connection and sympathy betwixt the retina and the
viscera of the abdomen is very particular 5 I have seen a proof
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 womer
suddenly, with head-ach 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 hallucinatio,
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 rnind 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 may 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
firequentes, sed a neaune quod*, sciam recte descripta causa ; hanc non ab humeri* alfluxode-
ducq, ut voluerunt, sed quia in magnit illis per paroxysmas convulsionum partium omnium,
et oculorum simul contorsionibus in quibus saepe quoque convnlsi, admodumque exerti et in-
flexi apparent, attracto sic nimium et tenso aervo optico, illis adnato illoque simul contorto
et teso, spiritusque visorii transitu impedito, oculos visiene privari contingit, atque inde pro-
venire diligente examine & consideratione inyenimus."  Platerus, Prax. lib. i. c. 7.
  t " (iuttula cruoris retinae insidens et nigricans, omnem lucem intercipiet unde phantasma
obscurum vel nigrum ; verum si dilutus cruor radios rubros transmittat tunc maculam rubram
videbit aeger ut omnia trans vitram inspecta rubra sunt."  Sauvage, vol. iv. p. 287. 
ib'
OF  THE RETINA.1
 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, antl,
 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 iact 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 e  periment,  in which it was ne-
 cessary to look upon  a luminous body, was seized  with giddi-
 ness, and 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
 theposition of his eyes remained stationary.  He then directed
 a person to  repeat  this experiment, and then bade  him  look
 steadfastly 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 foUowipg quotation refersto this sensation :—" JJger in magna hice constitutes, ut
plurimum presbyta, vel oculis nitidissimis gaudens continue prse oculos observari sibi'putat 
h
                        OF THE  RETINA,                      47

    There is a kind of umbrae seen  before  the eyes which are
 occasioned by  the vessels of the r.etina.   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 eye:ball, and  accompanying violent head-ach,
 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
 oyer the  eye-lids 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-
 bility. J   The night blindness, however, is not to be entirely at-

 puncta lucida, quae non hucet illuc volitant, nee a commoto capite agitantur, utputat la Hire
 et ejas iu hoc exscriptor Boerhaave; sed constanter si oculus immobilis remaneat, deorsum
 lentissime delabi videntur; adeoque veluti pluvia aui ea prae oculos eaque densa cernitur;
 quae verticaliter semper descendit in quacunqtie capitis positara, sive erecta, sive lateral iter
 inclinata ; hoc in me ipso expertus per annos, observavi in aliis, poti.«simum illos qui studio
 nocturuoiudulserant, etin aegrotante, qui deeo symptomate ad melancholiam fere per multos
 unnos solliritus erat. '  Sauvage. This appearance has been attempted to be explained upon
 the  supposition of a very sensible state of the retina, which perceives the gutula? exuding from
 the pores of the cornea, and which, falling over its surface, gives the appearance of their de-
 scending. But it is only felt when the retm.i is exhausted  or disturbed by pressure on the
 eyerbaU.  See Sauvages SuffuafoScintillans & Suffi  Danaes.
  * There are^ however, easeflof Amaurosis a myosi, in which there is a contracted and
 immoveable pupil, and children "are horn with an insensibility of the organ in which the pupil
 is not greatly dilated.  I would be willing to attribute this peculiarity of the pupil and ap-
 parent amaurosis in newly born children to the remains of the merabrana pupillaris.
  f  The sympathy of the iris with  the retina 1 do not conceive to be immediate, 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 tlie retina of one eye affecting the iris of the other, or the disturbance
 of the brain, in comatose diseases, destroying the sympathetic connection betwixt the retina
and  pupil.
  \  Est immanis differentia inter splendorem et activitatem lumini* candelap etlunae: luminia
Solaris vis est ad vim  luminis candelx 16 pedis distantis, observante D. Bouguer ut lltHi*
ad 1; et ad lumen lunae in pleni lunio, ut 374,000 ad 1 demonstrate D.  Euler Mem. de 
I
 48                 OF THE  RETINA.

 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.*

   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, be 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
 another ship, in which he continued ten days, during which
 time the  blindness returned only  two nights, and  never af-
 terwards.
    In  the August following, he complained of loss of  appetite,
 weakness, shortness of breath, and a cough ;  he fell away very
 fast, had frequent 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,f servant  to a miller,  at the 6th rffill on the Limehouse
 wall, about 40 years of age, came  to me October *2d,  1754, for
 advice and assistance.  He  told me, that about two months
 ago, while he was employed in mending some sacks,  near the
getting of  the sun,  he was suddenly deprived of sthe use of his
i'Acad. de Berlin, an. 1750, pag. 299. non mirum itaque si vistoties major sufficeret ad sue-
fit iendam rctinam quam tanto minor non afficiebat.  :,auvages Amblyopia Crepumdaris
         ■ By Dr. Heberden.       + Case by Br. Samuel Pye. 
OF  THE RETINA.
4$
limbs and of his; sight,   ^t "the time he was attacked with this
extraordinary disease, he was not only free from any pain in his
head or his limbs, but, on the contrary, had a sensation of ease
and pleasure;  he was, as he, expressed himself, as if in a pleasing
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  with-
out 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  increas-
ed, till it became  as perfect as ever; when he rose from bed,
his limbs  were restored to their usual strength and usefulness,
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 de-
parted from him,  and  he  became as blind as on the preceding
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.
   Boerhave  gives us  an  example of imperfect vision, from a
discordance betwixt the contraction of the iris and the excite-
   vol.  in.                   G 
50                 OF THE  RETINA.
ment of the retina ;  so that the pupil did not dilate in the pro-
portion to the decay of light.*
  WThen 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 relax-
ed, and the obscure light admitted, and this obscure light, from
the irritable state of the retina, gives a vivid  sensation incom-
prehensible to the bye-standers. Our judgments of the strength
of sensations are comparative merely ; when we have been ac-
customed to  strong impressions,  lesser ones  are  disregarded.
The greater light destroys the capacity of the retina for receiv-
ing 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 be-
coming more acquainted with the invisible properties of light;
and we have frequent experience of darkness being  relative,
end 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-
pil, 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 dnring
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 chane*-
of light.                                                    6"
  - Viz. by Dr. Reid. 
OF  THE RETINA.
51
my 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 appeased 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 mid-
dle line of the five  which compose the staff of music,  the mid-
dle 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.  San
difort The--, vo'. iii. page 314. 
52
OF  THE MEMBRANA PUP1LLARIS.
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.

              OP  THE MEMBKANA PUPILLARIS.


 X HE 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.
   Hallerf 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 ves-
sels ramified without an involving membrane, he naturally con-
cluded, that a membrane  was drawn across the pupil  of the
foetus, though in this instance, it was about to disappear.
   In several other foetuses of the seventh month he confirmed
his first observation ; and, cutting off the cornea, he observed
th# 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  whom 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, bebd. 18. as quoted by Haller.
* De nova tunica pupil lam fetu9 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."
 Si 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 pupilla?.  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 other
 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, " 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-
 pillae."  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 crystalline
 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 remains 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 opapue,  and very vascular membrane, and gene-
** See Medical Commentaries, p. 63. foot note. 
 54         OF  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 vessels, viz.
 the vessels of the capsules and those of the iris; but whether
 the arteries come by the  one source, and the  veins depart by
 the other, I  cannot  as yet determine.   In  one  preparation 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 betwixt this membrane,
 which closes up the pupil, and that matter  which 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 womb.  Towards the ninth month, the
 membrane has  become transparent, and if  not  totally absor-
 bed, 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, 1 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,  durine
 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. 
           OF THE  HUMOURS  OF  THE EYE.          55

which 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 EYK.
                OF  THE AQUEOUS  HUMOUR.


 JL HE 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 in-
to 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.
  + There certainly appears sufficient room for this  in Vesalius and Btiggs' platf*: 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 opin-
ion, 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-

  * Sec 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 fore-
part of the sclerotica. M. Merry and Bonhomme (see Zinn,; p. 143c) 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 HUMOURS  OF  THE EYE.
51
liary processes can  have little power of  filling the posterior
chamber, even from the connection of membranes behind the
membrana pupillaris in the foetus.   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 al-
lowed  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 k\v days he took off the  bandage, and showed them
the cornea again distended with  the aqueous humour.   It was
soon foand that  the instilled  fluid was  of no kind of conse-
quence.  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,  he. and from
the same cause, sometimes, proceeds a bloody effusion.  When
the pus has lodged in the anterior chamber of the aqueous hu-
mour, it would  appear, upon the authority of Galen,  that an
oculist of his day performed  a cure by shaking the patients'
head!* It is  an operation of oculists to puncture and allow the
pus to flow out, and some have even syringed out ihe pus with
water :f but  this must have  been on the principles  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 he sanguine in the  hope of
such an operation saving the eye.  Sometimes there remains,
after operation on the cornea,  or  in consequence of ulceration,

  * Mouchart says, he has often seen the oculist "iVco'hnu.'e rc-p'-at this cure by shaking ' Js
patient's head over the side of the bed. He attributed the cuie to the f;.*!ing of tlie pus
into the posterior chamber, which, he sunposes, hi* pi.it- we capable of ah-wnin? it.
  t They were at  variance regarding the place il  which ■;. jimcture for ti;i? disi-rirse: -
Some did it behind the iris ; there weknow tlvre i< h crowd of vt^e:-,; ifV busi place is 1 !x
lower edge of the cornea before the \vh.  Ii seems '•> li.r.e Wit no ,ti • n;iM  ^ccifi^nf, ':;
this operation, to find the lens protruded through Hi., rupii.  'Dx re.r.-. i t.  ;,u\, \i& ' it:« at"
ready explained.
  VOL.  HI.                    H 
58          OF  THE HUMOURS OF THE  EYE.

a continued flow of the aqueous humour; the consequence i*
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.

  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
humour. J 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.
                 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.
  The form of the  crystalline is that of a compressed sphere,

  * Rhytidosis, seu subsidentia & corrugatio cornea?.
  t Viz. Syuisesis.. There has occurred congenital imperforation of thepupil
  \ It is according to Dr. Monro, in the proportion of 1016 to 1000.
  * QpUialmograph'w.authore G. Briggs, 1676. Cantab. 
OF  THE HUMOURS  OP  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 5| lines
in diameter.   The internal structure of the lens is quite pe-
culiar, and resembles neither the vitreous nor the aqueous hu-
mour.  By maceration  it splits into lamella?, 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 its form, density, and central nucleus, it has great pow-
er 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 aranea improperly called,f which
membrane is continued  from,  or  connected  with,  the  mem-
branes of the  vitreous humour; but this is a subject which re-
quires a more particular investigation.
OF THE CAPSULE OF THE LENS AND VITREOUS HUMOUK.

                   Marginal Plate 13.

          Fig. 2.                        Fig. 3.
Petition Canal. —4r—^^mm^^^^mSmM  Vitreous humour.
  In fig. 1. we have the appearance of the Pelitian 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.
     f OphOutomographia. 
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 of
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 tuis 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 punc-
ture, 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 01 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 des-
cribed 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 tunica; retime
or membrana vasculosa  Ruyschii, which forms the vascular
capsule  of the lens in the fcetus, 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 ex-
pansion, splits  when  it approaches the margin of the lens.
One lamina  t;oes round behind the lens, and the other passes  a 
OF THE  CENTRAL  ARTERY.
m
 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 lami-
 nae of 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, beyond  which the
 medullary part is not  continued; but the membrana vasculosa
 passing onward, as I have described, embraces the lens, and the
 lamina, which passes behind  thejlens  and before  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 reflected  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 foetus, are supported,
 and that it shows throughout the same character for vascularity.
 Again, I think it probable that this membrane which passes be-
 fore  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 lehs 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.

 1 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.

  * In thefetus, 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 per-
fectly red with iujection, 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 com-
plete is the adhesion of the adventitious and vascular tunic of the lens to the membrana pf.
pillaris. 
<S2
OF THE  CENTRAL  ARTERV.
   The arteria  centralis retinae arises from the ophthalmic ai-
terv.*   Sometimes it is derived from  the ciliary arteries be-
fore 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 cribrosa
through the vitreous humour to the capsule of the lens.   This
vessel does not pass  exactly in the centre of the vitreous hu-
mour, 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 it.t
   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 foetus; 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 rami-
fy on the retina, to be arteries, when, in reality, they are veins;
he conceives, that the free return of the  injection from the ex-
tremities 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  accompanying  artery.   It is a supposition
contrary to the  general frame of the economy, and  I would op-
pose 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 tunica
vasculosa retinae.
   We frequently observe, that the .trunks of veins and arteries,

 * See Haller, Fascic. vii. tab. vi. fig. 2.4. 7.
 t Haller, F. vii. p. 42.
 \ Walter (de venis otuli)  says, the arteria centralis retina?, having perforated the mem-
hrana  hyoloidca, 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 forward, nor does it divide into a great number ol
branches in the posterior part of the capsule of the lens, like radii from a centre, as Zinn has
described.  He asserts that the lens receives its vessels from the investureof the membrana
hyoloidea, and that they run back from the edge of the lens towards the posterior convexity. 
OP  THE PELLUCID MEMBRANES          68
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 opbthalmica cerebralis, but often
it rises from  the carvernous sinus, amongst the origins of the
external and inferior recti musdes 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 retina?.  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 pro-
cessess.
   Whether a branch of the vena  centralis retinae 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.

     OF 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 re-
view 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 anvinclined
to think, that there is no such circulation through them ; and I
believe, that this would be much  more generally allowed  were
I here not something like a proof remaining in men's minds that 
64
OF  THB  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 fxtus.?  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 dif-
ferent destination ?
   I believe  this is a view  which has been little attended to;
but, upon the most minute enquiry,  and upon examining the
preparations of the vascularity of the eye of the foetus, I can
see no vessels passing into the humours and carrying red blood,
which are not finally distributed to the  membrana pupillaris.
When we lay open the eye of a foetus, after a very minute and
successful injection, we see vessels  which all  proceed  from the
centre of the optic  nerve, passing through  the vitreous hu-
mour to the back of the capsule of the lens, viz. the  branches
of the arteria centralis retina.  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- 
OF  THE PELLUCID MEMBRANES.
65
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 cap-
sule provided for the secretion of the lens, or were those ves-
sels the trunks of  lesser branches, which pierce into the sub-
stance of the lens, they would appear also on  the  forepart of
the capsule.
   If I am accurate in these observations, we are authorised 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  and 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 wars
   vol.  m.                  I 
66         OF THE PELLUCID MEMBRANES.

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 ANA-
                  TOMY OF  THE  HUMOURS.


JL HAVE already mentioned, as the principle of the operation
of extracting the lens, that the simple action of the muscles,
surrounding the tye-ball, 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 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 remov-
ed from the axis of the eye so far only that, in the case of the 
ANATOMY  OF  THE HUMOURS.           6tf
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, whije 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 pier-
cing the  cornea ; some directing us to pierce it at the distance
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 ad-
vancing 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 trans-
fix 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 respecting the
size of the posterior chamber of the aqueous humour and the

  * In our most modern system of surgery, we are directed to enter the needle one-tenth of
an inch.  To my certain  kuowledge, not only the ciliary body has been injured by this di-
rection, but even the root of the ins has been seen to be pushed forward on the point of the
needle. 
68           ANATOMt  OF TH"$  HUMULRb.
place of the lens, which have long been corrected. With this,
also, I think ougiit to have been forgotten, the idea of the ri-
sing 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 round  with the
vitreous  humour:  but as  the  lens only is opaque, as its  firm
connection with  the vitr.  ous humour, and even the rolling of
the  vitreous humour itself cannot be seen, this rolling  ol the
lens appears  to be the consequence merely of its own buoyan-
cy  in the aqueous  humour.  This adhesion of the lens to the
vitreous  humour, I have been sensible  of during its depression,
f.-om the elastic nature of the resistance which I felt.  \\ hen
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
n • one,  who 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
 mc.-t 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  effect 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-
* &e Mr. Benjamin Bell's System of Surgery. 
ANATOMY  OP  THE HUMOURS.
/2£k
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 the 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  oty*
"struct the light.
                       CHAP.  X.


 OP THE MANNER IN WHICH THE EYE ADAPTS ITSELF TO THl
                   DISTANCE OF OBJECTS.


 X  HIS 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 pencjls 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,
beinc 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 encrease its power
of concentrating  the rays and enable the eye to see near ob-
jects 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  muscu-
lar 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  ade-
"  quately accounted for,  but may be fairly made out by sup-
"  posing the  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
"  cornea, 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
"  on the other,  may be considered  as  two antagonists  in a
"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,  but, in  this action, to
alter the configuration of  the whole eye;   The eye-ball 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
eye-ball, 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 eye-lids, by
compressing the  eye-ball, 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 eye-lids; but I conceive  that he has  deceived himself,
in ascribing to the compression of the eye-lids 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 pu-
pil, from the degree  of opening of the eye-lids.  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, Keil. Monro 
72              DISTANCE OF OBJECTS.
the action of the orbicuUris muscle,geem to .him adapfecf.ta
the end proposed.  In the first, experiment,, when ]jie opened
his eye-lids wide, and endeavoured to read a book, the letters
on which  were so near the eye as  to be indistinct, be found
that  he could not do it.  In the second experiment, keeping
the head  in the  same relation i6 the book, ,he-brought the
edges of the eye-lids within a quittter 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 tliis experi-
ment I find the action of the,eyeTlids 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 eye-lids 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 eye-lids, 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 1 found to be  produced by the  marginal hairs of
two flat camel-hair brushes, although the eye-lids 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 orbicularis 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 eye-ball.  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 tp 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 was no perceptible change
* Philog. Trans, for IP, 10, 
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 accommo-
 dating itself to the distance of objects.  As to the fibrous struc-
 ture of the lens, there  can be no doubt: first, it is rent by fis-
 sure, then split into lamina, and can be finally teased  out into
 fibres.
   This structure was first observed by  Leuwenhoeck; he has
 these words :—"Porro vidi corpus cristallinurn ex tam tenui-
 " bus coacervatis constare squamis ut ubi  eas  oculo diimtior,
 " dicere  cogar,  pluris bis millenis  sibi invicem  incumbere;
 "ubienim  corpus cristallinurn ab ejus membranula seperas-
 ct sem, ejus  adhuc axis, ubi crassissimum  erat, (non enim est
 "perfecte rotundum, sed aliquo modo planum) duas tertias
 "pollicis partes retinebat;  ergo a centro ad circumferentiam
 " est tertia  pollicis pars atque quoniam, ex dimensione mea
 " 600 pili lati pollicis quadrati, longitudinem conficiunt 200 pili
 w lati pollicis tertiam partem adaequare debent.   Atque nunc
 " video ubi denae squamae sunt coacervatae, eas capilli nostri dia-
 " metrum nondum adaequare ; ergo his 10 cum 200 multipli-
 " catis,  sequetur, ut dictum, plures 2000  squamas in corpore
 " cristallino  esse coacervatas. Porro vidi singulas has squamas
 " ex filamentis, concinno ordine juxta se positis, constare adeo
 " ut  singulae squamulae unum filamentum sint crassae ; &;  ut
 " hanc substantiam fibros earn ex qua corpus cristallinurn con-
 stat ob oculos ponerem, earn, lineis in circulum ductis quan-
 " turn pote designavi."
  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 revi-
ved by the insertion of Mr. Young's Observations on Vision in
the Philosophical  Transactions.*  The  following  are  Mr.
Young's observations on  the appearance of the lens :—" The
" crystalline lens of the ox is an orbicular convex transparent
" body, composed of a considerable number of similar coats,
" of which the exterior closely adheres  to the interior.   Each

                      * See  vol. for 1793
VOL. III.
K 
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 semi-diameter of the coat;
" their arrangement is that of three equal and equidistant rays,
" meeting in the axis of the crystalline; one' of the anterior te
" 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
 *' 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 circumfe-
" rence 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,
" Between the mass and its capsule  is found a considerable
"' quantity of an aqueous fluid, the liquid of the crystalline.r
FIBROUS  STRUCTURE OF  THE LENS.
Fig. 14.                         Fig. 1„.
  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
leasli possible degree of power.  Again,  how are they relaxed r
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 dis-
tances 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  a 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 830th 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. Trims1.
f Ibid, 
76
DISTANCE  OF  OBJECT*.
of the tendons of tlm four straight .muscles, so  as  to know
whether their action could be extended to the cornea or not;
he found them to approach within f of,the,cornea before their
tendons became attached to the sqlerotic ,goat.  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 actipn of the re^ti, 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, theii; effect
would  be to flatten the cornea, by drawing out and extending
its margin.  This is a circumstance which Dr. Monro has re-
marked; and Dr. Monro  has also,  with more accuracy of ob-
servation, 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 conti-
nued 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, much at a loss to determine which 1 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 life-time, 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 ob-
ject distinctly at three inches distant from the eye ; at 12 feet,
less distinctly; and when  he looks upon the objeet 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
pbjects, those nearer become indistinct. Now this indistinctness
of the object,  seen  when he examines narrowly the  objects
beyond them,  would argue (did we admit thjs muscular power 
DISTANCE OF OBJECTS.              77
in the eye of adaptingitself 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,'or5 any other intermediate
distance, to be more distinctly seen  than the fixed and perma-
nent constitution of th^eye admits.
  L cannot help concluding, therefore, that the mechanism of
the eye has not so gre'it 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.
~-*9+B—
                       CHAP. XI.

                 OF  SEEING IN GENERAL.

 J. HE efe 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 njake dis-
coveries in the sphere of the fixed stars!  Agaip, 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 croeked in the mind as well a? 
78
OF  SEEING IN  GENERAL.
in the body ! Yet, notwithstanding the perfection of the sense
of seeing, much of this perfection is gained by the other sen-
ses  and  particularly  by that of touch.  If the  human body
were motionless and inert, the sensation conveyed by the eye
would1 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. solidi-
ty, convexity, and angularity, " the visible  idea exciting in us
"■ 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 whatis the act of the memory
and judgment.*
   We 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
the object and the sensation of it, but merely a connection es-

  * See Dr. Jwta on Mr. Molyneux's problem, Smitk's Append, p. 27.
  T Euclid, and others of the ancients contended that rision was occasioned by the emission
of rays from the eye to the object. He thought it more natural to suppose, ihat an animate
substance gave out an emanation, than that the inanimate body did.  In l.r>60, the opinion
was conflrmed that the ray? entered the eye.—The sensation was not always believed to be
in the. retina : it was by some believed that part of the ien(=alion was to be attributed to
ilie crystalline. Kepler, in 1600, shewed, geometrically, how the rays were refracted through
all the hnmours of the eye so as to forma distinct picture on the retina; and also be shewed
die effort of glasses on the eyes.  See further, regarding the opinions of the ancients, Boer
liaave Prelect. Acad. torn. iv. p. 2R2. 
OF  SEEING  IN GENERAL.
79
tablished by nature, as certain features are natural signs of an-
ger ; or1'by art, as articulate sounds are the signs of our thoughts
arid 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 of
the pupil and of the  crystalline  lens, and  which consequently
falls upon the middle of the  retina ; and the axis of both eyes
produced, are  called the optic axis.  But  the axis of the eyes,
it is evident, are not always parallel; for when both eyes are
directed  to a near object, the axis of the eyes meet in that ob-
ject ; but when we direct the eyes to the  objects in the heav-
ens, 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
axis of the  eyes may be much further altered from the natu-
ral 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 eye-ball 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
OF  SEEING  IN GENERAL.
 no longer painted on corresponding points of both. This simple
 experiment leads us to consider wha£ is the, qopstimlion and
 correspondence, of the eyes, that whe# each has thje picture
"of the object impressed upon it, we should only see it single if
 the eyes- are sound and perfect.
  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 eye 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 thpy
do not fall on  the centre of the retina, they  fall oil the same
side of the centre in both eyes.   But if the  eyes are made to
fix steadfastly on an object, and if another  object should be
placed before the eyes within the angle which the axis of the
two eVes make with the first object, it will be seen double/be-
cause 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  doub;e
somewhere near the outline d 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
  liearer the eyes, or much more distant from them than that to
  which the two'eye"!r are directed, appear double*  Thus, if a
  candle is placed at the distance of ten feet,  and I hold my
  finger at  arm's  lengrh 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 shew,  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 in 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 if 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 corres-
 ponding 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, (if 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 tenacnlae.   Very large  animals,  as  the whale,
elephant,  rhinoceros, hippopotamos, have,  in proportion to
fheir bodies,  very small eyes: so have  the animals which  live
   VOL. III.                    L
                                                     / 
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 ofrays 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
eye-ball 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 actifJn 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 refuted 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 ample 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.aensibility 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 principle.   Most people  who squint, have a defect in
 one  eye, and  this is the distorted eye, while the other is di-
 rected in the true axis to the object.  Now the mind does not
 at^nd 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 squint-
 ing, the impression on the weak eye in a short time ceases to
 be attended to,  the  strong  and vivid impression is  alone per-
 oeived, and single vision is  the  consequence.  It  is evident,
 then, that those  who squint must have a degree of imperfec-
 tion  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 eye-lid  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 per-
 ception 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
 eye-ball; 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
-»fn a manner to avoid all interference.   Blows  on  the head, 
84*
OF SEEING IN GENERAL.
drinking and smoaking, and a variety of irritations, occasion-
ing convulsions and distortion of the eyes, cause double vision.
As this is evidently produded by the affection of the* muscles
moving the  eye-ball,*  since any change upon the retina could
not give occasion to such distortions in a state of insensibility,
we may naturally  conclude,  that  squinting  is sometimes the
consequence of irregular action of the muscles ;  for if those
transient causes are apt to affect  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,J}y
any  means,  accomplish."];  This shows  the  strict  correspon-
dence betwixt the  moving muscles of the eye-balls.  By this
experiment, we shall find the difficulty of that method of cor-
recting the squint proposed  by Dr. 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
distorted eye, a weakness which they do  not observe, from

  * The  command of voluntary muscles is first lost in intoxication; and, therefore, it is
more likely that the muscles should lose their natural action and correspondence than  the
retina.               i _
  f In Smith's Optic's, there if a case of squinting and double vision occasioned by a blow.
In Buffon's Dissertation, m the Acad. Roy. des Sc. 1743, squinting after long continued
painof thehead.  In the Mem. Roy. de  l'Acad. des Sc.  1718, Hist, p, 29, there is a cu-
rious instance of false vision. I find also quoted several cases of strabismus from sudden
fright, in Ephem. Germ. cent. 3. it 4. obs. 152. p. 349.  Ib. dec. 3. an. 8. & 11. ob. 57. d.
114..  Ib. dec. 3. an9 & 10. obs. 67.  "  Novi Juvenem paralysi obnoxium, cuicum cjeteiis
oculi sinistri musculis relaxatis, addvcens fortius contraheretur propter oculuni ita distortum
obJEctum qnodcunque duplex apparebat, nee quod verum esset distinguere  potest."  Willis
de anima Brut. P. Physiol, p. 77.  An instance of the,kiss of corresponding motions of the
eyes, and strange illusions of sight  See in the Enquiry into the nature of mental derange-
ment by Dr. Crichton, vol. i. p. W7.
   X It is said that astronomers, who are much used to attend only to the impresesions of
one eye, are sometimes able to squint at pleasure. See Mr. Home,  Phil. Trans. 1797,
p. 17. 
OF  SEEING IN  GENERAL.
85
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, bf tying up the'sound
eye, the weak one becomes  gradually stronger, so'thai'the
person becomes able to read with it: mnch may 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 eye-balls.
  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 :—
" 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. Rei«|. 
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  thiqg ; 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 any 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, witlj 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 be 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 side-way before  my right eye,  the whole  letters of the
page seem to move, leaving  distipct  and  stationary a circular
spot containing a word or two.  Here, by  no effort,  while I 
OF  SEEING  IN GENERAL.
37
look 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 chuse  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 in-
stances 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 letters 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 eye, 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 it 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 eye-ball.   The double
vision is the effect of discordance in the  action of the muscles. 
( 88  )
CHAP. XII.
OP  THE EYE-LIDS, OP  THEIR GLANDS,  AND OF THE GOURSB
                      OF  THE  TEARS.


.HAVING completed the description of the eye, as the or-
gan of vision, we have now to attend to its connections, its ad-
ventitious membranes,  the glands of the eye-lids, 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 an-
terior surface 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   eye-lids.  It goes a little back into
the orbit,  and is  again reflected, so as to come forward and
cover the forepart of the eye-ball.  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 tbe 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.
  Eye-lids.—Birds which  mount into the higher  and clearer
regions of the atmosphere have a third eye-lid, 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 is
called membrana nictitan^. 
OF  THE EYE-LIDS.
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 enumer-
ation 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 sclero-
tic coat is seen  under it; and in consequence of  this, the
tunica conjunctiva is sometimes called albuginea.
  A very  materialpart of the  structure of the eye still remains
to be described f an apparatus  by which  the surface of the
eye is preserved from injury,  kept  moist and perfectly trans-
parent.
  The  eye-lids  are  composed of the common integuments,
with this difference only, that they have a cartilaginous margin
to give them shape, and muscular fibres, in tbe  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 eye-lid, 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  carti-
lage  of  the eye-lid is called tarsus.
  The upper eye-lid only, is  moved for the admission of light
to the eye ; it is raised by  the levator palpebral  muscle.   But
the  eye-lids  are  shut again  by the  orbicularis palpebrarum,
which acts on both eye-lids, and sometimes with such power, as
to squeeze the eye-ball even to a painful degree.
  The  meibomean glands.—These are very   elegant  little
glands which lie under the inner membrane of the eye-lids.
About twenty or thirty ducts of these glands*>pen upon the
tarsus of each eye-lid.   These ducts run up under the vascular
membrane of the inside of the eye-lids, and minute glandular
fblicules, to the amount of  about twenty, are,  as it were, attach-
ed to each of these ducts.   These glands exude a vhite  seba-
ceous matter, which defends  the edge of the eye-lid from the
acrid tears, and closes them more accurately by its unctuosity.
The vascularity of the inner  surface of  the  eye-lid 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 eye-lids, and tne
mouths of the ducts,  are  sometimes eroded with little ulcers.
These ducts are the seat of the stye.   This is an inflammation
  vol.  in.                  M 
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 eye-lid,
accompanied with  inflammation  of  its cyst or surrounding
membrane.

     OF THE  SECRETION AND COURSE OF  THE TEARS.

  The lachrymal gland is seated in the upper and outei*
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  eye-lid.  By the reflection of
the membrana conjunctiva from the eye-lid over the surface of
the eye-ball, dust and  motes are prevented from getting  be-
hind the eye-ball; and  when they have got under the eye-lids,
the extreme sensibility  of the tunica conjunctiva excites  the
lachrymal gland, and  the  orbicular muscle of the  eye-lids,
(which, by its pressure, accelerates the flow  of the tears,) and
the dust or motes are washed out.   The puncture for re-ab-
sorbing the tears and conveying them into the nose, being at the
inner angle  or canthlfs  of the eye-lids, we see the intention of
the ducts of the lachrymal gland opening on the  inside of  the
upper eye-lid towards the outer angle : for, by this means,  the
tears are spread over all the surface of the eye-ball, by  the
motion of the eye-lids, before they  decline into''the  puncta.
But the tears  do not  flow only  when the gland is excited by
motes ;  their secretion is perpetual, and, together with the mo-
tion of the eye-lids, they perpetually moisten the surface of the
eye-ball. 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 eye-lids 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 eye-lid: 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.
   The caritncula lachrymalis is that little granulating-like
 body Which lies in the  inner angle formed by the two eye-lids; 
OF  THE SECRETION  OF TEARS.          91*
 VeTy small hairs are seen to sprout from it, and some small sa-
 baceous  folicles open upon its surface.  Connected with the
 caruncula lachrymalis is the membrana or valvula semiluna-
 ris.  This is a vascular  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
 eye 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 lach-
 rymalia,  but for  accumulating  and throwing  out  the  motes
 and dust from the eye, and for guarding the puncta from the ab-
 sorption  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 eye-lid; it is in them called membrana nictitans.
   The lachrymal sac  and duct lie in the os  unguis or lach-
 rymale.   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  maxillary 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  a vascular, 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 evaporation
 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 SECRETION  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  teases,  mixed  with mucus, are forced
back through the puncta; by and bye the  sac  inflames  and
suppurates; matter is discharged by pressure of  the sac : and,
lastly, it is eroded and burst out, discharging the tears and mat-
ter on the cheek.  This is the complete character of the fis-
tula  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 proceeding  from the
caries of the os u nguis,  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 obstruction 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
 he surgeon. 
BOOK  II.
OF  THE  EAR.
>?£'
CHAP. I.
      OF THE SOUND,  AND OF THE EAR IN GENERAL.


 _L HE 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, D3
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 vibratidn, 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 sounds
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. 
94
OF SOUND.
   That  water conveys the vibrations  producing  sound, has
been proved by experiment.  It was once the saying of natu-
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 Bri-
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  Nollettook 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  body.J  He observed in other expe-
riments, that the  more sonorous the bodies struck were, the
less  vivid was the impression ; by which 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 incredulous of the
effect said to be produced  by music on lobsters.  Some may he so still;  but we may trust
tlie following observation of Minasiu?, in his Dissertation. " Su de timpanetli dell udito
"■ scoperti nel Granckio Paguro."  " Propriis observalionibus certior factus asserit obscura
'"• nocle, placidoque mari quoties piscatores ardentibus saculis paguri in littore haerentis oculos
" lucis fulgore perstringunt, ut stupido, etpene prastigiato animale potiantur, fl forte rumor
" aliquis ingniit.  Cancrum illico se e  littore  subducerc recipereque intra undas." Set
Scarpa Disquisiliones Anatomica; de Auditu in Insectis, &c.
 X These experiments were repeated by Dr. Monro. See his Book of Fishes. 
OF  S0DN6.
95
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, 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 partly in this way
that we are to judge whether deafness may be cured  by oper-
ation, 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 enquiring 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 THE EARS OF ANIMALS.'f


 JL HERE 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  communica-
ting 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.
  t In the following short account of the comparative anatomy of the ear, although I have
taken every  assistance in ray power from books, 1 have described the structure, in all the
examples, from my own dissections and observation. 
9b'
OF  THE EARS OF 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 by 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 amphibiae ; in  the more complicated
structure of the lungs of birds; we observe one essential requir
site through the whole gradation, viz. the  exposure of the cir-
culating fluids to the action of the air.  And in this variety of
conformation, we  see the same effect so modified as to corres-
pond with the 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 he,art in
the human body, by tracing the variety of structure through the
the several classes of animals ; from the simple tube circula-
ting the fluids of insects, the single 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 fcetus in  utero,
is, in the same degree, capable of illustration from comparative
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 com-
plex structure.
  The simplest form of the organ of heaving  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  ?uch  an  orean, 
OF THE EARS  OF  ANIMALS.
97
 breathe the air, a membrane closes this sacculus on the forepart;
 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 Ihe 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 canal 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 as in 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 integumt nts 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
easily, and which is destined to  agitate the fluid in which it is

  * It is conceived by some that the antennae of insects conveys to them the vibration (S
bodies, and that they may be considered as an imperfect variety of this organ.
   VOL. III.                  N 
98
OF  THE EARS OF ANIMALS.
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 con-
tained 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 tkin,  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 enquire a  little 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
under water. It appears opposite to the general law of nature,
to suppose any species of fish having that simple and more de-
licate  membrane which is  evidently intended to convey  at-
mospheric 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 atmos-
phere.
  When  we  come to examine  the ear of the skate, we find,
shat 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 trutb.f   To me it
 appears,  that this narrow duct cannot be considered as the ex-
 ternal 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 any
 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 fenestra? 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
 intended for propagating the motion  communicated through
 the water.

  * " In the upper and back part of the head of a skate and in a large 6sh weighing 150
 " pounds, at the distance nearly of one inch from the articulation of the  head  with the
 ■' first vertebra of tlie 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 Audi-
 " torii Extern!."   Treatise on the Ear, p. 208.
  f ' 'ft Scarpa, speaking of this opinion of Dr. Monro, says, " qua in re vehementer sibi
 " hallucinatus est, ostra nimirum ductuuni inucosorum, ut manifestum est, pro auris meatu-
 " bus accipiens.  Etenim omnino nullum est in cartilagineis pitcibus ostium auditus eKtus
 " adapertum, membranaque fenestrce ovalis sub communi integumento recondita jacet et
" cooperta."
  X " Quod et absurdum est et a rei  veritate quam onaxime alienum."  Vii. Anatomical
 " Disquisiivmes de audilu et olfactu, auctore A. Scarpa. 
100
OF  THE EARS  OF ANIMALS.
  In serpents, birds,  and quadrupeds, we shall hereafter trace
the various gradations 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 lubes
and sphericles of the  internaJ 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 unision 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 lapillje  lying in their
sac. 
(101 )
CHAP.  III.
■description op 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 lobsters, 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 au-
ditory  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 ex-
ceedingly 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 vi-
bration 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 this0
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 fe difficult to ascer-
tain 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  fishes,  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 acaus-
tic 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  membranous canals.
These membranous tubes contain a fluid distinct from that con-
tained 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 ©artilaginous
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 fishesIT is first divided into
two  fasciculi, which  are again subdivided into lesser nerves.
These go to the three sacculi lapillorum, and to the ampullula-
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.
  t 1" many of the spinous and squamous fishes there is only one. In cartilaginous fishes.
these bodies are not hke bone, but like soft chalk.  In the spinous fishes,  on theother hand
  7£F     shape rf *•* head rf a sPear'md ,,ard like f*t°*""e
  X The gelatinous matter is rather before the bones, and distending the little sacculi.
  i See plate7. fig. 3. and fig. 4  d d d.
  |J_ So Professor Scarpa asserts, in contradiction to others.
  t The fifth pair of nerves in fish answers to the seventh in man: has the same  division into
the portio 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 semi-
circular canal is distinct 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 of 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       Cf
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 ; while, 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 ampullulae, and a common

 * This is the appropriated appellation of the opening which lends 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 stretch-
         ed over the little cavity.   This first bone is placed at a right an-
         gle with a second bone, and both are lodged in a proper tym-
         panum.f   This second  bone swells out towards its  inner ex-
         tremity, and is accurately applied to the  foramen ovale.   The
         foramen ovale opens into a cavity which we  must call the  vesti-
         bule, and which, in this creature, is peculiarly large in propor-
         tion 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 beautiful whiteness, and of  a regular figure  when
         first seen, but has no solidity.^  The  vestibule  here, as  in all
         other animals, being the immediate seat of  the sense, is filled
'l        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  for-
         ward.  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 substitute as the frog :  the outer extremity of the bone seems
         rather attached to the lower jaw by a cartilaginous appendage
         and small ligament.1T 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 m general coupled with deafness, it is natural to suppose it has no ears.  This
         is to consider the organ as subservient to conversation !
          t See plate, fig. 5 and 6.
          X This tympanum being a cavity containing air, has communication with the mouth by a
         tube, which we shall afterwards find called eustachian tube. Several have erroneously des-
         cribed this animal as receiving sounds through the mouth.
          ||  See fig. 6. d.                               <-
          J Plate, fig. 7. b.
          IT See Scarpa, tab. v. fig. ix.
          ** Serpents are affected by music; and they will raise and twist themselves with ever?
         variety of lively motion to the pipe  and tabor. 
OF  THE ORGAN OF HEARING.
105
Through this  cavitv 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 into the vestibule ;
and a passage also opens from the cavity of the tympanum in-
to 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 with 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 of 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 ajskin 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.
                  OF THE EAR IN RIRDS.

   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
   vol.  m.                 0 
106
OF THE  ORGAN OF HEARING.
into these three cavities, there are two foramina;  the eenes
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 ossiculus
connects the membrana tympani (which  is  here of a regular
form) with the vestibule, and conveys the vibration of the at'
mosphere 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 zonuljf.
nekvosj<e.   But these are the membranous  canals, which are
contained within the bony ones, dried and shrunk up.   Within
the bony cavities of the  labyrinth, 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
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, (vid Phil
lraiis. A.  1800.) says, m birds this membrane has no tensor muscle to vary its adjustment*
but is always kept tense by the pressure of the end of the slender bone. This is a very im-
perfect account of the mechanism of the tympanum in birds. There are two bones, or one
small bone with a cartilage, which lies along the membrana tympani.   This elastic cartilaze
has two little teudons attached to it.  Even the slender bone which stretches from the carti-
age 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 con-
nection, I am unable at present to say.
 11 lately by accident, drew out the sacculus vestibuli and semicircular canals from the
™~n«-w^  rar «  $'iaD^1 f0"nd tb? Lme",hranous "wnicirailar canal to consist ap-
parently of the same pellucid elastic matter with those of frhes                  l 
OF  THE  HUMAN EAR.
107
the vestibule, the other opens outward into the  cavity of the
tympanum.*
  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.


 A HE anatomy of the human ear will naturally be consider-
ed 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 termihate in the concha or immediate opening of

  * We find Mr. Home saying that the cochlea is neither absolutely necessary to fit the or-
gan 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 by that part being wanting in birds, whose
organ is particularly adapted to inarticulate sounds.  That the cochlea is not necessary to
the communication of sound through the atmosphere, we have seen from the examination oi
the ear of the reptiles.  But since we see that it forms part of the labyrinth in binds, we
 miv be lsd 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 Europe-
ans, 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,  tb,e edge of which
is turned over, and forms the cavitas innominata.
  bcd. The antihelix.  It is very prominent; of a triangu-
lar 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 ANT1TRAGUS. 
OF  THE HUMAN EAR.
109
   fe. The tragus.   These are the two prominent points which
 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 recognized 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 fis-
 sures.  The internal part of the tubers formed in the bone, as
 we 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 glandulje CEROMENOSJE.f  These glands, se-
 creting the  wax of the ear, have their  little ducts opening be-
 twixt 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-

  * See Valsalva & Santorini.
  + " Has figuram obtint-nt variam; major tamen harum pars vel ad ovalem, vel ad sphaeri-
"cam accedit colore tinguntur flavo abhumore in earum folliculis contento qui ob assiduam
44 fibrarum carnearum reticularium pressionem, per cutis correspondentia fiaramina in meatus
" auditorii cavitatem transmittitur."  Valsalva de aure humana, p. 10. 
110
OF THE  HUMAN  EAR,
quence of  the  brain partaking of the  inflammation.   Such
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 se-
cretion from the glands of the tube will cause a degree of deaf-
ness :  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 birtb, 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, hav-
ing 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 affligentis  curatio." The
older writers treat of the " Auditus lffisio a sordibus aurium lapidescentibus."  See Bondus
& Jul. Casserius Placantinus, " De auditus organo," Hb. 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 stuffi
up the passage in the fcetus. See Fabbicils de Chirurg. operat. cap. de aur. Chirurg.
Vesmkcius Anat. cap. 16.  See Experiments on the Solvents of the Ear-wax by Dr. Hay-
garth, Med. Obs. and Inquiries, vol. ir.  p. 198.  He gives the preference to warm wa-
«-r over every other solvent.
  f Bee plate 3.  fig. 3. 
OF  THE HUMAN  EAR.
Ill
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 of 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 ex-
ceedingly small spiculaj 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 ova let 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 forward, like it, but enters on
the side of  an  irregular projection : it does not lead into the
vestibule, but into one of the seals 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 irregulari-
ty.   Where the tympanum leads backward into the cellule
mastoidea, this periosteum is also continued.
  The Eustachian tubeJ 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  approaches 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
cavity.
  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-

  * 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.
  + Fenestra ovalis.
  t Iter a palato adaurem.
  I By some older writers, the Eustachian tube is called aqueduct, because they conceived
that humours were evacuated from the tympanum by this passage. 
112
OF  THE  HUMAN  EAR.
mosphere and the air contained within the ear, the motion of
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.   I
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 this membrane be tense, it is not stretch-
ed uniformly like the parchment of a drum,  but  is drawn into
a funnel like shape by the adhesion of 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 verv 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.f   This is carrying  the conceit of their analogy too far.

 * The following case is from VaLsalva:—" Quidam pfebeius ulcus gerebat supra uvulam in
" sinistra parte, quod quidam earn, quam invaserat, partem exefent atque abstuleret sic, ut
" ulceris cavitas cum extr«mo sinistra? tubai oriGcio communion et.  lgitur quolies homo
" mollem turundam reinediis iinbutam in ulcer's cavitatern iittnuiehat: toties illico sinistra
t aureevadebatsurdus.talisqne permancbat toto ex tempore quo turunda in ulcere relinaue-
" hatur," p. 90.                                             M
 t bet Mr. Home's lecture on the structure and u«e r,f the membrana tynirani  Pli"
7';.in..!.-'  Pirtl. 1800                                  ' '  '" 
OF  THE HUMAN EAR.
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 organdie 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 m vlleus* receives its  name from  a resemblance to a
ha inner or mallet;  it is, in  some degree, like a bludgeon ;
the great head stands obliquely off from the body of the bone
                  * See plate 9. fig. 1. a.
VOL. III.                  P 
114
OF  THE HUMAN EAR.
(if such  it may be called) like  the head of the thigh-bone.
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 clown  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, qs  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 stapksJ 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

  * See plate 9. fig. i. b.        + See plate4. fig. i. o.     X See plate 9. fig. i. c. 
OF  THE HUMAN  EAR.               115
neck of the bone, has the long handle  or body of the bone
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.*
  * Valsalva has the following  observation, see page 24. "Olim namque incujusdam surd'
" cadavere surditatis causam in eo sitam inveui nempe quod indicata membrana in -oibstanliam
" osseam indurata, unum continuatum os constituebat cum basi stapedis et margine fenestras
'* ovalis." 
116
OF  THE HUMAN EAR.
The stapes,  then, acts like a piston on  a membrane of much
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 tbe Eustachian tube, called the  spoon-like
cavity, and is inserted into  the long process of the malleus.
The tensor TYMPAMf runs  also by the bide of the Eusta-
chian tube ; it is inserted into the body  of the malleus ; it is a
long and slender muscle.  Tbe external or superiorj muscle of
the malleus, which is denied by some anatomists to be of the
nalure 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 stapedius^ is the smallest muscle, and is attached to
the smallest bone.  It has  a  small round  fle hy 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 insetted either into the  malleus or
stapes, and not into the middle bone, it would appear that their
operation  is chiefly upon the membranes of the  tympanum,
and of the foramen ovale, through the medium of the bone im-
mediately 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

  * Musculus processus minimi mallei.  Valsalva.
  T Musn.lns processu majoris mallei.
  X Muscuiu  ;>. oces.--tis minoris.  Valsalva
  | Thio mu.ck- i- particularly strong in the horse, where it was first discovered by Casserius. 
OF  THE HUMAN EAR,
117
 "•* inward and tightening the membrane of the tympanum ; tbe
 " other two act in an  opposite direction,  and  relax the rnem-
 " hrane."*-  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 bone 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 worthy 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 mu-
 sic.  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
* Mr. Home's Lecture. 
118
OF THE HUMAN EAR.
 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
 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  phrenzy  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  symptons 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 he affected.
   We now proceed to put the incorrectness of this reasoning,
 concerning the muscular power of  the  membrane of the tym-
 Eanum, in a  more particular point  of view, leaving to Mr,
 tome'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
membrane ;  but his ear remained nicely susceptible of musical

 * Case.   This gentleman had been attacked, at  the age of ten years, witfe an inflamma-
tion and suppurat'on in bis 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, wer*-. observable.  The Immediate consequence of these attacks was a total
deafness, which continued for three  months; the  hearing then began to return; and, in
about ten month' from the last attack, was restored to the state in which it at present re-
mains. Having filled his mouth with air, he closed the nostrils, and contracted the cheeks:
the air thus compressed  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 is-
sued 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 membrane on the left
side was entirely destroyed, since the probe struck against the petrous portion of the tempo-
ral bone.  The space usually occupied by the membrana tympani was found to bean aper-
ture without one trace of membrane remaining.  On the  right side, also, a probe could be
passed into the cavity of the tympanum 5  but here, by productint; it along the sides of Uie
meatus some remains of the circumference of the membrane could be discovered, with a cir-
cular opening in the centre, about the fourth of an inch in diameter. See Trans. Rov Soc
"or  1800. Part. I. p. 131. 
OF  THE HUMAN EAR.
119
tones, " 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 conformationis vitio inter tan-
 " dum  istud  experimentum, (viz. an  ossiculi et membrana
 " tympani aliquis sit usus auditum,) quod inopinato et feliciter
 " successit cuidara, 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 Valsalva's experi-
 ments they healed up very soon.  But,  when there is no other ingresS  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, F.pist. \n. XII.  The membrana tympani is very vascular, I
 have it red with injection. See Ruysch. fig. 9. tab. 9. Epist. An. VIII-
  + Biolnnus Bncherid. Anat. lib. 4. c.  4.  Sc? also Bonetus de Anrium Affect.  Obsorv
 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 Anima
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 bad 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 fine 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 tbe
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. J
  Induration of the membrane is less of an imaginary disease,

 * Sec Ruysch. Epist. Anat. VIII. tab. 9.
 + See Du Verney de Organo Auditus p. 41.
 X " Relaxatio fit ab humore superfluo qui membranam  hanc humectat et symptoma hoc
" coramuniter cum obstnictione meatus ex tumore glandularum conjunctum est. d." qui jam
" supra dictum est: muituin autem tacit ad difficnltatem audiendi in personis qu„ 1, r'uxoni-
" bus catarrhosis obnoxiy sunt et per eandem  rationem austri nebula? et aer pluvius auditum
" minurut ut experiri quotidie possumus."  Du Verwy 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 bones, is  prevented,  and a degree of deaf-
ness 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 it-
self.  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,
J have seen, to be nearly tbe 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 filled with matter, and  a thin greenish fluid lay
betwixt  the  temporal bone and dura mater.  I  have since
found the caries of the  petrous bone from this cause fatal.

  * See the London Philosophical Transactions for 1800, Part I. p. 5.
  ■J- 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
 •■rtain foramina which he discovered.  See p. '10.
  ; See Valsalva. P  If.
  VOL.  1W.                   Q 
122
OF  THE HUMAN  EAR
  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
sometimes from suppurations beginning in the outward ear;
and  we may suppose that the apparatus within the  tympa-
num  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  were 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 neg-
lect  the duller sensation.   The consequence of this, is, that
the bad ear becomes worse.  It is much like that effect which
takes place in eyes by squinting.

 •Valsalva,  p. 83.  See also a case in Bonetus de Aurium Affect. Observ.I., andOul.
Ballonius Epid. et Ephem. lib. 2. p. 270. When the matter wap miP iressed,  there came
pain of the head, and weight, which yielded to no remedy: on direction, there was found
an abscess withm the, skull.  In Bonetus loc. cit., a case i~ 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 incus was wanting. See Bonetus de Aur. Affect. Observ IV 
OF  THE HUMAN  EAR
123
                    SECTION III.

                   Of  THE  LABYRINTH.

  The labyrinth  is the internal  ear: the proper seat of the
dense 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 foveae, 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 academica 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 formina 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 Vemey (Euvres Anatomiques. 
124
OF  THE HUMAN EAR.
ovale, transmits the vibration intp 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, we 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.   Valsalva 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.
  Tbe 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-
•vard= the apex.  Tt is formed in the most anterior part of the 
OF
THE HUMAN  EAR.
125
petrous bone, and has its apex turned  a  little downward 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 tbe 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 oi
the tube lead from the one into the other.

                          Fig. 19.
A. Scala.  B. Lamina Spiralis.
C. C. Modiolus.  D. 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 scalje cochleje : 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 scalae.   It is called 
m
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.                                            «H
  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 communica-
ted through the cochlea, must pass either from the tympanum
into the foramen rotundum, circulate round the  modiolus 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 circulate round
both the semicircular canals and cochlea.
  In the dry  bones, when  we cut into the cochlea, 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 tbe  cochlea,  has shrunk
and fallen away in the dry state of the parts, the lamina spiralis
is like a hanging stair, and  the scalae are not divided into dis-
tinct passages.  In this bare state of the shell of the cochlea,
when we cutaway 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 supposing the cochlea to rest on its base. 
                   OF  THE HUMAN  EAR.               127

 the modiolus is a nucleus, axis, or central pillar, is a contradic-
 tion 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 di-
 minishing 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 of 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 £:Minct branches of
 vessels 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 auoitorius 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 tbe three
divisions of the labyrinth, whilst a larger one conveys a portion

  * In a preparation before me, I see a considerable artery derived from the basilar artery,
enteriii" the meatus auditorius internus.  From tbis.trunk, I conceive that most of these ar-
11 lies which I have described are derived. 
128
OF  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.J  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 which these fo-
ramina take,  this is named the tractus spiralis foramino-
losus.   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 spicule of bone stand across some of
them. There is a range of these  foramina which stretche?
from  the  tractus spiralis.  This  may properly be  called the
tractus calthratus rectus;^  they do not lead into the ves-
tibule, but into the beginning of"  the lamina spiralis, where it
divides the two scalae 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 fovea 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 fetus, it becomes here superficial.
  t This is the aqueduct of Fallopius.
  X See Scarpa, Plate VII.,fiir. i. m.
  i Trcetus spiralis for:iniiiuIo«i initium. Scarpa 
OF  THE HUMAN  EAR.
129
"Oule is rough and spongy : it transmits a portion of the nerve
to the sacculus in the hemispherical sinus of the vestibule.*
    or 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 theVx-
treme branches of the  portio mollis distributed among them.
Betwixt the soft and organized sacculi and tubes and the peri-
osteum of the osseus labyrinth, a watery fluid is exuded.
   Sacculus vestibuli.  The hemispherical and semi-eliptical
foveae 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 sac-
culus lies in the semi-eliptical fovea  of the vestibule, or like the
other sacculus, is  in part received into it.  This sacculus re-
ceives 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 difficulty .f
Upon pressing the common sac,  or the ampullulae of the semi-
circular canals, tbe fluids are seen to circulate along the mem-
branous tubes of the canals.  These two sacculi in the vesti-
bule lie together, and firmly adhere, but do not communicate ;
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.
   + Proprio humore turgidusadeo translucetut ablongura bullnlam scream mentiatiir. S^"
 ya, p. 47.
   VOL. III.                     R 
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 ampullre 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 say nothing from my
own dissection.
SECTION IV.
                      Or 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 cy-
lindrical form adapted to  the  foramen  auditorium.   While
these fasciculi are wrapped in one common coat, they are mat-
ted 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

  * "  Caeterum universum hoc canaliculorum membraneoruin alveique communis roachinn
" mentum saneuil'eris vasis instruitur, quorum crassiora, circum alveum communem, serpen-
" tino incessu ludunt: crebra et conferta alia ampulla imprimis recipiunt ob quam causair
" rubellar plerumque sunt et cruore veluti suffusa?."  Scarpa, p. 47.
  i 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 tbe
outer surface of the  sac, and has a beautiful  fibrous texture ;
but upon the inside of the sac upon which it is finally distribu-
ted 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 under-
stood that an unorganized matter is meant.
  That part of the nerve which stretches to the ampulla?, 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 of 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, pas-
sing  along the modiolus and scalae cochleae are in their course
subdivided to great minuteness.  Part  of them perforate 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. 
C 132 )
CHAP. V.
                 OF  HEARING  IN  GENERAL-


     HEN 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, would rest satisfied with  the
 fact that sound was received upon the drum of the  ear.  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 tbe  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 of 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 tbe  air  is  diminished, and the membrane  prevented from
vibrating.*

  * See Retkerches, &c. relatives a I'orgnw de Vouv. 'ta lit propagation dcssov*, par M
 Pernlte, Societ. R. de Medecine. lr>jo. iii.
w 
OF  HEARING  IN GENERAL. ,          133
   In the tympanum, we have seen that the operation  of the
 chain of bones is to encrease 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
OF  HEARING  IN GENERAL.
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, tbe vibration must have been re-
ceived 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 scalae 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-
'' tundce advectis utraque  in facie percellitur et una cum pen-
" cillis acaustici nervi.per earn  distributis contremiscit: quibus
-' porro omnibus, in ampullis videlicet caniliculorum semicir-
" cularium, alveo eorum communi, sacculo vestibuli spherico
" et lamina oochleae spirali acaustici nervi affectionibus audi-
" turn contineri nemo non intelligit."*
   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
* 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-
 tions 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 enquire 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 pos-
 sesses 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 impressions
 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 si-
 milarity of figure and place in these canals through all the va-
 rieties  of animals, from fishes to man.   It would seem to  indi-
 cate, that there is in their form and position  a.peculiar provi-
 sion 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 those 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 foufid in the  sensation ; for example:—" The ear
" 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-
" 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
" elastic  air are required, which must all be of equal duration
" and extent, and follow  one another with  perfect regularity;
" and each undulation must be made up of the advance and
" recoil of innumerable particles of elastic  air, whose motions
" are  all uniform  in direction, force, and  time.  Hence we
" may  easily  conceive a prodigious  variety  in the same tone,
" 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
" ear itself upon which  the impression is  made.   A flute, a
" violin,  a hautboy,  a  French horn, may all sound  the same
" tbne,  and be easily distinguishable.  Nay, if twenty human
•' voices  sound the same  note, and  with  equal  strength, there
" 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
i{ natives, nay by different provinces of  "the same nation, may
" 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.
s See Reid's Enquiry        i Reid's Enquiry, p. f>8 
DISEASES  OF THE  INTERNAL EAR.        137
CHAP. VI.
          OF THE DISEASES  OF THE  INTERNAL EAR.


 v-JF 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 faultering 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 tbe 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 faultering 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 pugnique magni-
 tudine, cerebrum et cerebellum inter, eo precise loco ubi conariura utrique suhsteritur cho-
 roidis plexus alae, spatio semestri a sensibili laesione, caecitatem  primo, surditatem subinde,
 omnium denique seusuum et functionum animalium abolitionem et  necem ipsam intulisse."
 Bonet. vol.  i. p. 123. ob. 53. In Sandifort Obs. Anatom. Path. torn. i. p. 116. there is an in-
stance in which the auditory nerve had a cartilaginous tumour adhering to it.
  t F. Hoffmann. Consult, et Respons. Cas. xxxix. We must  not, however, take his rea-
soning after what we have seen of the structure of the ear, that the viscid petuita, separated
in the concha, cochlea, and labyrinth, resolved intohalitus endeavouring to escape, produces
the susurrus et tinnitus aurium.
     VOL. III.                  S 
138       DISEASES  OF  THE INTERNAL  EAR.
nicans faciei.   From observing the course of the nervus 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 ieason 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 brain.J   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 haermorrhoids, in surfeit, &c. in which cases it is
often preceded by vertigo and head-ach.
   There occurs a very curious instance of analogy betwixt the
ears and eyes  in  the following cases:—" 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 ryhme or measure  but of  a different tone.   His hearing

 * Hoffm"inD- Med. Consult.  Boorhaave.  The sympathy is sometimes exerted in another
way:—  Ex musices tonitru aut sola meatus auditorii externi contrectatione, vomitus urinae
" Incontinentia ". Sauv.
  t pysecoea (atonica) sine organorum sonos transmittentium vitio evidente.  Cullen. Co-
 P <°d\^"v-.£°PAos" a Paracusi distinguitur ut amaurosis ab amblyopia respectiva. Sauv.
  X But the difficulty of knowing when the deafness is the result of disease, or malconforma-
Uon in the part- transmitting the sound to the nerve, and w lia in the brain and nerve has
led to more uncertainty and contusion with regard to th*> -.. tit- and vaiieties  of the dUor
ders of the ear than in the eye; where the transparency of the humours a«sist in the de
Drtition. 
           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 impru-
 dently 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 si-
 tuation.  He complained that when any person spoke to him,
 he beard 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 re-
 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.  iii. p. 352. 
BOOK  1H.
OF  THE  NOSE AND THE  ORGAN  OF
                 SMELLING.
               OF  THE  SENSE OF SMELLING.


OMELLING 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 would 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 tbe sensaton of smell.   Even in the
outward form and  structure of the nose, there is a relation to
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 the  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 ath-
moid bone; these cartilages perform another office in giving
that  flexibility  to this prominent feature, which enables it to
elude injuries and at tbe 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 cir-
culate about the cells of the aethmoid bone,  where  the ol-
factory nerve is expanded.
   Immediately within  the nostrils,  there are two cavities se-
parated by the  bony partition,  which has been already des-
cribed in treating  of the bones.  These cavities  enlarge as
they proceed inward,  and open backward into the throat, and
consequently, 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 sufficient-
ly 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 asth-
moid 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 schneioekiana, 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 penetrate
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 tbe 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 sensibility. 
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 tbe frontal bone, and no sense
of odours was  experienced ; but when  they  were  admitted
downwards to the aethmoid bone, the first nerve was affected,
and tbe 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 ad-
monishes  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 al-
teration of its natural  properties;  by the infarction and thick-
ening of the membrane, as in ozfitna;  by obstructions  pre-
venting  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
tbe approximation of  some tribes to the brute,  dwell much 
OF  THE SENSE  OF  SMELLING.           143
on the acuteness of sensation enjoyed by negroes, and their
wider nostrils.*
  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 fire 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  irri-
tation upon it.
   There has been a most interesting communication made to
me by Mr. Thomas, 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.


  * Pallas says, the Calmuck by applying his nose to the hole of a fox, or any other beat'.
^an tell whether he be at home or not.—See While of Manchester 
BOOK IV
 OF THE  MOUTH, SALIVARY  GLANDS, AND  OR*
                   GAN OF  TASTE.



                        CHAP. I.

                OF THE MOUTH AND TONGUE.


  J. HE 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  tbe nostrils into the trachea.
   Tbe lips and cheeks are formed of the skin and reflected mu-
 cous 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 glandulce labiales and are
 very numerous, those of the cheeks are called  the glandules
 buccales.

                     OF THE  TONGUE.

   The body of the tongue consists of muscular fibres, with in-
 termingled fat and cellular membrane ; and the muscles which
 chiefly compose it, are the  linguales, styloglossi, and genio-
 glossi 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 dor-
 sum ; 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 maximae
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. XCNF 
OF  THE MOUTH  AND TONGUE.         145
with the bottom of the fossula? 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 rSany
which he examined.  In Holler's opuscula there is a disserta-
tion on the Duct of Cosckmzianus, 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 discov-
ered 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  oeso-
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  papillje 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 papillas  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 papilla?, 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 LiNGuae.
This ligament seems evidently intended  to  limit the motion
of the 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 theos hyoides;
and his opinion was, that they had even a connection with the thyroid gland. Heister was
of the same opinion.
  VOL. HI.                   T 
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 m >uth. ' But, observe the
bad consequences which may arise from  cutting this frenulum,
and yielding to the obstinate impertunity -i  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 linguae. 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  \he 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 trie 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 ; 1  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 tbe 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
daring the night.



                       CHAP. II.

                OF  THE  SALIVARY  GLANDS-


 I HE sources of the saliva are very numerous; the parotid
glands or superior maxillary gland, and socia parotidis, the in- 
OF  THE SALIVARY GLANDS.
147
ferior 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 dilatable
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 of
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 frenuni 
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 molaris
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 tiie mouth so as to salivate.
CHAP. III.
   velum palatinum;  uvula; arches of the palate;
                     and amygdalje.

 T
  A HE  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 velpm palati is not  square, but turned into
 elegant arches; and, fyom 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 distance from each other, so  that the isthmus of the
fauces resembles the double-arched gateway of a citadel, or the
arched roof of a cathedral, with the uvuja banging as from the
central union of four semicircular arches.
Fig. 20.
t7vula......-4'i
Amygdala.
The Toiijiic.
ti»... Anterior Arch.
Posterior Arch

of the Palate
  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 nnse ;  and there being, at the same time, an
action of  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 Vol. I. Constrictor Istlimi faucium and Palato-pharyngeus. 
150                   amygdalje.
stomach.  The velum also is a principal part of the  organ of
the voice.
   amygdalae.  Betwixt the arches of the palate on each side,
lies a large oval gland of the size 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, 1 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 tbe
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 gland 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 irre-
gular,  that they may  retain  the  mucus  until ejected by the
action of deglutition.  In  this operation, the  amygdalaj 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 ac-
count of the structure of the oesophagus and stemach, in the
succeeding part of the work. 
151  >
CHAP. IV.
                of the sense of tasting.


KJN the surface of the tongue are  to be observed many pa-
pillae,* 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 we 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 felt: 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 tbe 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  tbe  tongue.   Before we taste,  the  substance
dissolved in the saliva flows over the edges and point of the
tongue, and  then only cdmes 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-
* AlbiMfl Arm. Acad. lib. i. cap. xr 
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 un-
necessary 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 fullness 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 tlmrt  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.


  1 IJE 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 corking 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 pe-
 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 futus 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 workmen, and in a remark-
 able mu.-iei' in  the feet of those who have been accustomed
 to walk jare-foot on the burning sands.   It  is thus a protec-
tion  to the foot in a state of nature.   But if the skin be too
 much or too quickly exerted, instead of forming additional lay-

  * 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 stin.  Adversar. Vru'om. III. 3.
  f Albini, Annot. Acad.
  VOL. III.                   TT 
154
OF  TOUCH AND OF THE  SKIN.
ers of cuticle, a serous fluid is thrown out from the true skin,-
which separates the cuticle in blisters; and this over-action of the
skin will throw off the cuticle, as we see to be the consequence
of the irritation of plasters or cataplasms, scalding water, exan-
thematous diseases, erysipelas and mortifications, &c.   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 ex-
cites 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, tbe  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.J  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 tbe 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. vL cap. vi. et vide tab. ii. fig. 1.
  f Santorini Observ. Anat. cap. i. ii.            } De hum. C. fabrics, lib. ii. c, v. 
OE  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
 ?rogress is stopt until the cuticle is burst  by the distention.
 'his 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 by the
 extremities  of tbe tendons,  which extending beyond the flesh
 were dried  and hardened ;f and the celebrated Albinus des-
cribes  the nail as formed by the conversion  of the papilla?
which lie under irj : 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 tbe 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 corres-
ponding surface with them.
* See Hunter on Blood and Inflam. p. 469.
\ Annot. Acad. vol. i. lib, ii, cap. iv.
f Riolanus.
 { Winslow. 
J56         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.   Within 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
(he American, and lastly 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 tbe hair falls off gradually,  and tbe  young and the old
hairs are together growing at the same time.  Hair is of uni-
form  thickness in its whole length; whereas wool is variable in

  * Vide qua de hoc Albinus Aniraadvertit. Acad. Annot. 1. vi. cap. ix. and Mor«aeni
Adversar. et Epist. An. iii.  $ 4.
  t Mr. White of Manchester tells he has seen a lady with hair six feet in length:—a Prus-
sian soldier whose hair trailed on the ground. 
OF TOUCH AND  OF THE SKIN.
157
the thickness of its filament;—further it has been found, that
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. 1 his shows  us how the fleece becomes coarse and hairy
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 fibrillae  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.   Mickel be-
lieved  it to be only a mucous fluid, inspissated into the form
of a membrane;  and that it  was dissolved by  putrefactioh,
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 \u
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 that the 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 tbe 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.f  When

  ■*■■ Malpighi de sede negridinis in Ethiope.   It has appeared to me that there was a greai
deal of colour in the cuticle of the negro, and so Morgagni, " negricante et fusco colore in
lectas."  Adversar. II. Animad. IV.  See also Blumennach 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 tlie inhabitants of the plains. Humboldt also asserts (con-
trary to Volney) that, in the yn-ovinces of Spanish America the children of Indians are cop.
per coloured from the moment of their birth.
  t Priestley's Experiments.
  t The Gradation in Man, by Charles White, of Manchester.—Some have said that ex-
treme cold also tans the skin, at the Laplanders, the Esquimaux Indians, and Greenlauders,
are dark: opposed to this, we find the Finlanders and Norwegians f;iir beyond other Euro-
peans. There is much in the habits of life; a painter will not find his carnation  tints amongst
' he poor—nor in the skin of a Highlander; yet where so pure as in a Highland lady ? 
158         OF 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 excitment of the living
vascular surface in the formation of new  matter, or the  dis-
cbarge of colouring matter into  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 mu-
cosum is softer  and more pulpy, the  outward surface  more al-
lied 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.f  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 platefrom a preparation of
Mr. Cruickshanks. For opinions regarding the cause of colour in tlie skin, see Albinus de
seek et causa Colons jEtkfopium, Sugd. Batav. 1737.  Haller Element. Phytiolog. vid.pag
•JO.—Blumenbach de generis humani varietatenaiiva Gottingee, 1795, page 122, and noteT^ "■'
  + Mr. Baynham, who discovered this vascular surface, conceived that he had injected the
rete mucosum.  Ruysch and others mentioned by Albinus, supposed they had injected the
cuticle when roost probably they had torn off the vascular membrane, or as Albinus al-
leges, Acad. Annot lib. vii. c. ni. in taking off the cuticle they had torn up the vascular
papilla? 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 of 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 lamina,  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 neUwork 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 firmness, 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 vermillion, 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 irregular-
ly 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 tlie Rev. S. S. Smith, of tlie American Plulosoph. vSo-
 ety, 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 handst 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 ;f 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,
a,nd that which ministers to the other senses and to our neces-
sities most of all;—it is the sense necessarv to the existence of
every living creature.

  * Albinus Dissertatio de Sede et Caus. Color. iEthiop. Malpighi, et I'.xercit «!e Tact ■
Organ.
  * Videde Panillis Ctitb. Albini, Ac.  Annot. lib. \1. c. x. and Riivsch- 
OF  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 ari-
sing'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 bad 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 proted4|on 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 the 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.  Lavisier 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 Philadelphia,
who proved that the air so collected upon the surface was at-
tracted from the water not exhaled by the surface.
  Vol. hi.                   X 
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 1 have said,
the attraction of the oxygen of,the atmosphere forms the car-
bonic acid.  Thus the  function of the skin  is brought to re-
semble, 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 independ-
ent of perspiration, still undoubtedly,  the free or checked per-
spiration of the surface  is a means of equalizing the tempera-
ture 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 tbe 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 absorp-
tion  by the surface, unaided by friction,  abrasion, or ulcera-
tion.*
   The  more important function  of the surface  is to be con-
templated in its effect  on  the general activity of the vascular
system,  and in the vicareous 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 ib

         ■' Rolloon Duh»ff»  r>  Curric, Abfje Fontana, Dr. Watson. 
OF  TOUCH  AND OF THE SKIN.
165
which we see the disorders of the viscera affecting 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-
sease on the skin, but to take the means of exciting the latter
as a remedy for the former.  In  the same manner will the  se-
cretion  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 shewing that health
is enjoyed when the various functions, which 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
THE  PLATES
                  Explanation of Plate  V.


                         Fig. 1.

 V
 ± HE eye with the cornea cut away, and  the sclerotic coal
dissected back.*
a.  Tbe optic nerve.
b.  The sclerotic coat dissected back, so as to show the
       vessels and nerves of the choroid coat.
cc. The ciliary nervks 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, but appearing to give off no branches.
ee.  Two of the venje 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.
1.  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. 
 
/-
r
I'r! . m
Fie.. /.
 
 
r.i.ni
■*},,
i~U
r. j-o.
-g.-i.     /'
Pig. 4
,-<«7r -"
I
l  <.
'•    t-ta?  M'
Fig. 5. 
 
I W.J//.

met  10/
r 3#iJ
Fig-.l.
K;.\
>icr. 3.
lg. 4-
'"iy. 5.
J.tntv if' 
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.
n.  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 VI.
                         Fig. 1.
  The lens covered with its capsule, and minutely injected
in the foetus calf.
A.  The ARTERIA CENTRALIS RETINJE.
b.  The fringe remaining  with the margin of the  lens from
       the attachment of the vessels of the ciliary body.
                         Fig. 2.
  This figure shews 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.
g.  The membrana pupillaris, very minutely injected.
d.  The iris,  to the circle of which, the membrana pupilla-
       ris 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 foetus of the seventh
month.
                         Fig. 4.
  The appearance of a vessel which took its course across the
pupil in the full grown foetus,  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 VII.
                         Fig. 1.
  The representation of an eye with a cataract, dissected. 
 166        EXPLANATION OF 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 formed
       an adhesion with the  iris.
                         Fig. 2.
   This figure represents the effect of  couching a soft cataract.
 Tbe needle, instead of depressing the cataract, cut it into
 three  pieces.
 aa.  The cut edge of the sclerotic coat.
 b.   Tlie choroid goat, and ciliary  processes.
 c.   The cataract adhering to the ciliary processes in three dis-
       tinct 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 Jens 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 humour.
 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 VIII.
  Showing  some varieties  in the structure of the ear in the
lower animals.
                         Fig,  !,
  The  ear of the lobster. 
IW III.
P.302.
Lenty tc*. 
 
EXPLANATION OF THE PLATES.
16?
a. The membrane which covers the projecting mouth 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 three 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 enlarged so
    as to fill up the foramen ovale, which leads into  the inner
    cavity of the ear.
i  , 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 openinginto tbe 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 tov  isr.
a. A large scale which serves  the use  of  the  membrana
    tympani.
b. A single bone which is sf en 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 IX.
  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.
e. 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 bone 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.
f. The malleus, the long handle of which is seen to be at-
    tached to the membrane of the tympanum e.
a, The incus, united to the great head of the malleus f. 
Voim.
f&tL/A-
Fig. 2.
F504..
liff.i.























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&H-4-
Fia 3.
JjM <M'. 
 
 
Vol. in.
&& X
/' 300\
Fro.
Fio. 2.
BeU Jtl?
Ceney n- f 
            EXPLANATION OP  THE PLATES.        169

 H. The stapes, which is seen to be articulated with the long
     extremity of the incus through the intervention of the qs
     orbiculare.
                         Fig. 3.
   Shows the division of the temporal bone into the squamous
 and petrous portions.
                         Fig. 4.
 a.  The squamous part of the temporal bone.
 b.  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. 5.
   The petrous portion of the bone, with a view of the tympa-
 num.
 a. 9 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.  6.
   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.
                        Fie.  7.
  Explains the manner in which the lamina spiralis divides the
 cochlea into two scalae, 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.
q.  Cellular structure of the bone.
D.  The FORAMEN ROTUNDUM.
e.  One of the scal« of the cochlea which is seen to termi-
      nate in  the foramen rotundum.
 v.  The other scala, which is seen to communicate with  the
      vestibule.

                Explanation of Plate X.
  These two figures  are taken from the beautiful plates of the
  VOI,. ni.                    Y 
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.
1.   A filament of the nerve  to the sacculus vestibuli.
m.  The lesser branch of the acaustic 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.
p.  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 internus.
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.
c.  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 gangliform swelling of the nerve.
i.   The greater branch of the anterior fasciculus.
k.  The lesser branch.
I.   A filament of the  anterior fasciculus to the hemispherical
      vesicle of the vestibule. 
            EXPLANATION  OF THE  PLATES.        171

m.   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.
11.  u u. Their further distribution on the lamina spiralis.
V V. The  INFUNDIBULUM.
x y. The  last turn and termination of the lamina spiralis in the
      infundibulum. 
 
THE
AN A  TOM 3
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,
but 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 ne-
cessary to accuracy and minuteness, from leading us to consi-
der 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 gra-
dations 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 body 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 ex-
ercise, and  renovated  through the influence of the circulation.
The continued action of a muscle is followed  by feebleness,
and the continued impression of tbe 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
tlie first passages, there is thrown  out from the stomach a fluid 
SYSTEM OF 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-
propiate 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 duct, the 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 of
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 
17b
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 circulation,
bone to support the incumbent weight of the body; muscular
fibre, to  give  it  motion ; as well as all the other variety of
solids and fluids.   The only difference betwixt these solid de-
positions 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 class-
es; 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 arraugement.  The first division comprehends the fat, the 
SYSTEM OF THE  VISCERA.
177
marrow, 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 ser-
ving 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 shew a uniform result.*
  Perhaps all the correctness to which we  can an at present
pretend 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 of 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.
   Vol. hi.                  Z 
178                  INTRODUCTION.
powerfully change  the  nature of the secretion ;  the active
power of  the solids appearing to be an agent which controuls
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.
We  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 with 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 different so are 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 structure  of glands, we
find in the first instance that the old physicians contented them-
selves with saying that the glands or viscera  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
 »hese pores allowed only particles of a particular size or figure
* Van ITelmont.  Vi<»ti««en?. .v. 
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,f  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  a 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 surely 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.J
  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
witfi 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

  • Cliurlcton, Descartes, Borelli, Verhevn,&c. &c.          + Window. Helvetia.
  X Conor, Tentamen epistolare de Secretione.            "; Boerhaave. Pit'■whip. &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, yet 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 second professorship did he learn to  des-
pise 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;
the> 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 they 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 sometime 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 for 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 inves-
tigation.  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
folicules 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 efferentia, 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 distinct;
but  it is not a test of the  natural  structure, or implicitly to be
trusted to.
** Much coagulated blood was found in the ventricles of his brain by Baglivi, 
182
INTRODUCTION.
Scheme of MalpighVs opinion.
  Fig. 1.  Boerhaave's plan of  Malpighi's  doctrine,  a a a
folliculos glandularum simplicissimarum denotat.   bbb singu-
laria emissaria cuique utriculo a,  propri atque  in communem
canalem excretorium d, 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 foli-
cule or little glandular bag, E.  F, the ducts which receive the
secreted fluid from the folicules.
  Ruysch studied at Leyden, under Van Home, 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 tbe human body in the soft-
ness anil 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 be-
lieve to be  one  reason  of the  rapid  progress of Ruysch's-
opinion.

                    Scheme of Ruysch's opinion.

                          1 1
  1 1 The  smaller arteries  which do not enter into foli-
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 formed 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.   Tliere follows these a crowd of
French academicians, who, with Boerhaave,  may be consider-
ed 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 fo-
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 by  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
where 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 tbe  newer
school of chemical physiologists, but in truth gives origin to a
new school, de Part du cuisinier.   He  cooks it;  he  boils the
liver and the kidney, fkc. 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

  * Ruysch's doctrine again was thus opposed; " Ruyschius auget arte sua replendi exten-
sionem vasorum ultra naturalem raagnitudioem. Ruyschius arte .sua destruit glandulas ■
dein negat.  Ruyschius negat omnes glandulas. Melius est &  tutius omnia baec demon-
strare in cadavere recenti."  F. Ruysch Epist. ad Vir. Clar. Her. Boerhaave, p. 56.
  It may be further observed, that it was not in .the mere fact of there being folicules, in
wluch Malpighi and Ruysch differed; for the latter conceded that there were hollow mem-
branes, but contended that these were not glands.  Their difference of opinion is expressed
in the following words of Ruysch; " Adeoque discrepantia inter magnum ilium virum et
inter me est, quod ille putat humores delabi in glandulas dictas siuiplicissiuias,—ibi foveri
mutari: Ego puto, qaod arteria? ultima? succoslaciant, &factos ibi deponant." 
SYSTEM OF THE VISCERA.            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 entertain-
ed, that the blood issuing from  the heart immediately com-
mences a separation of its parts for the several  secretions, is
quite unsustained; 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 artery
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 cord 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 properties  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 resting 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 by cutting through the nerve I
This is still proceeding upon  an  old-fashioned  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, he.   This, while it explains the peculiarity of

 * Haller, by experiments, proved that several kinds of foreign matter may be conveyed
into the circulating blood; and Bichat has made the experiment of injecting all the animal
secretions into the veins of brutes.
  t Bichat has also taken the trouble of examining the blood of tbe carotid srtwy, smd
of  tbe spermatic artery, without being able to observe anv difference.
   vol.  in.                 A a 
186                  INTRODUCTION.
glands, admits  also of a vicarious secretion, that is, the pos-
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 im-
plies a secreting body, yet this does not follow from the defini-
tion 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 au-
thors who have  taught their peculiar  opinions regarding their
structure, we have a  still less  admissible description.   Thus
Malpighi defined a simple gland  to  be " Membrana cava cum
emissario ;" and Ruysch says, " Glandule non  nulla compo-
nuntur ex sola membrana cava cum emissario sed pra?cipue 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 tliere is a  division of glands
still  in use  into conglobate  and congLint rate.   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 Iefi 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. J
   ( ri/iAtz (implies cells or cavities) are numerous in the body.
We  have an example of them in the great intestines.^ Crypta

  * The terms acini, cotulae, crypta?, folliculi, glandula?, lacana?, loculi, utriculi have been
almost promiscuously used; being so many  names  for bundles,  bags,  bottles, holes, and
partitions.
  t 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
terra conglomerate, consisting of many little cavities  Tln?e lymphatic glands, belonging to
a distinct system, require no farther particular definition to distingkh them.
  \ See farther of the acini of the liver for example.
  5 Ruysch ad Virum Clar. H. Boerhaave, p. 53. 
OF  THE ABDOMEN IN  GENERAL.        187
is a soft body, consisting of vessels not completely surrounded
with a membrane, and resolvable by boiling or maceration.^
  Folicules  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.
  Lacunae 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  se-
cretes ;  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 sys-
tem.  This fact corrects the  notions which we should other-
wise be apt to receive of the action of secretion from  contem-
plating  the more complicated glandular organs.
*
»CHAP. I.
   OF THE ABDOMEN IN GENERAL, AND OF THE PERITONEUM.


 1 HE 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 alae  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 the 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 possitdistingui: "
fantura cjrcum afiusa rabedo per repletionem videtur." Ruysch ad Her. Boerhaave, p. f 7." 
188
OF  THE ABDOMEN  IN GENERAL.
   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 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 di-
   visions on its surface, which are  called regions*
   *- The epigastric region is the upper part of the belly, un-
   der the point of the sternum, and in the angle made by the car-
   tilages of the ribs.  Upon the sides covered by the cartilages
 - of the ribs are the hypochondriac  regions, orthe right and
   left  hypochondrium.   These three regions make  the  upper
   division of the abdomen, in which are seated the stomach, li-
   ver, 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
P  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
p  ilii, and behind the line perpendicular 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 fore part 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,
   consists4of 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-
*!!?eV£!&flf E°me an3t0n,istC'Saying' that the P^toneumU a double membrane, 
                 OF  THE PERITONEUM.              1£0

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/nuscles and ten-
dons of the abdomen.
  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.  From
the diaphragm it is also sent off upon the cesophagus 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 down 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 duplicature,
and forms the mesentery.
   The peritoneum also lines the abdominal muscles;  it  is re-
flected from the Diaphragm upon the surface of the transvei>
 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. 
190
OF THE  PERITONEUM.
    From this detailed description we see that the peritoneum
 has no termination; that it is continued from the surface ofthe
 diaphragm to that of the  abdominal muscles;  from that over
 the bladder and rectum ; from the rectum in the whole length
 ofthe 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 ofthe 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  VESSELS OF THE PERITONEUM.

    As the peritoneum is a membrane of great extent, and in-
 vesting a \ariety 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 intercos-
 tal, 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 be*
 dies in the peritoneum.

             OF  THE  USE OF THE PERITONEUM.

   The peritoneum serves as a dense and  outer coat to  the ab-
 dominal viscera; conveys the vessels to them, as in the exam-
 ple ofthe mesentery ; and,  having its inner surface smooth and
 lubricated by a  watery secretion, it allows the parts to lie  ia
 contact, (they being strongly compressed by the surrounding
 abdominal muscles and diaphragm,)  and at the same time al-
 lows in the intestinal  canal a capacity of motion without fric-
 tion.

 * We not unfrequently find an accurate general description in authors, but some incor-
 rrrlnesi in the subordinate detail; which throws back the ideas of theTeadeTinto corfurion
 Such » the enumeration of the holes or perforations of the peritoneun?' Z? dtSr ™-
 iaSe k l'oeeophage, k la ve.r^cave," &c.  See Anatom cfinnjTperM. ffi  lYe «
 that there are no such perforations, that the oesophagus never enterTinto the cavity of the
 peritoneum, nor does the rectum.pass out from its cavity. This was indeed Opined  b£
 Fernebus in oppowhon to Galen. See  a description of the inflections of the peritoneS  bV
.HarthoH ->;-earaen HistorBR Anatomicse Analect. Ob. J.           l^uoneum  oj 
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 absorbe >t 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 them.J  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 protusion, and forms a sac involving; this herniar.
   Nor do the processes of the peritoneum,  which have re-
 ceived the name  of ligaments, nor the mesentery, nor meso-
 colon, sucifliently 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 haturam secernatur dictu difficile est: ad uncias certe collect*
 aquula in sani hominis abdomine reperitur.  (Kaawn, 543.)  In nomine, cui sponte abdo-
 men sub umbilico ruptum erat ad quinquc & sex libras de die effluebat.  (Journ. de Med.
 1757. M. Aug. ut denique 800 libr. effluxerent.*) This, however, proves nothing of the na
 ture or quantity of the secretion: this has probably been an inflammatidn and abscess of thf
 peritoneum, which, we have seen, pours out such a quantity of fluid, thin and serous, as quick
 ly to drop through the bed-clothes upon the floor.
  t This vapour 1 have seen arising from the intestines of the human body during the ope
.ration for hernia; and also when the omentum and intestines have escaped in con*eqii<w <•><
 a wound of tlie belly.
  X Element. Physiol, torn. ii. p. 380. 
192
WF  lilt PERITONEUM.
part of the membrane which invests the stomach and intes-
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 ofthe surrounding muscles;
and the great  venous trunks which take their course through
the abdomen are in  a particular manner indebted to the pres-
sure ofthe 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 sometimes
produced, apparently by the balance ofthe vascular system be-
ing 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 ofthe cellular membrane,  which accompanies
the vessels passing out from the abdomen, productions of the
peritoneum.  The vaginal productions of tbe peritoneum are
the sheaths of the common cellular substance which accom-

  * Sec Anat. Chirurg. par M. PalGn. tonj. ii. p.  35. and note. a. 
                 OF THE PERITONEUM.              193

pany the aorta and oesophagus into the posterior mediastinum j
or which give a bed to the spermatic vessels, or passing under
Poupart's ligament accompany tbe 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 plica?,
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 carrygus again over all the ex-
tent of its surface.  When this membrane is reflected off to the
oesophagus from the diaphragm,  it forms 1.  the  ligamentum
dextrum ventriculi ; and 2. the vinculum oesophagi.   In  the
same manner is formed, 3.  the ligamentum inter ocsophagum et
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 capsularis :  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-renaie 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 peritoneum, 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 tlie
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*
  vol. m.                B b 
194
OF  THE PERITONLL'H-
turn minus, or hepatico-gastricum ;  omentum coiicum, dextrum
&c sinistrum ;  and, lastly, tbe 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 tbe viscera.
   The  omentum  majvr** 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 ofthe 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 ofthe 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 wasted and shrunk; sometimes collected info masses
 leaving the surface  of the intestines.
    My reader must  now find  his way into the marsupium, or

   * Praeterea tenerrimas esse ut nulla membianarum humanarum, retina oculi excepta
  scque sit tenera.  Haller, vol. vi  lib. 20.  "> 1. par.  12.
   While its delicacy is remarkable in the young subject, the retiform vessels (vid. Ruvsch
  Ther. 11. Q. V. SpegsL LV III. &c.) have the fat accumulated  iu their tract as ifit'were
  thrown up by them to a side; but often the fat increasing obscures the vessels.
   f Marsupium tbe common term.—Sec Window. IV. § &52. 
OF  THE PERITONEUM.              195
purse of the omentum,  viz. the porta omenti, 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 blowing into
this opening, in a young subject, three omenta are  distended
viz. the omentum hepatico gastricum, the colico-gaitricum, and
the coiicum.
  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 diseas-
ed in this  case,)  by operating on the  left side he  thinks the
water will  not  be allowed to flow from the sac of the omen-
tum.   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 ofthe liver at the  transverse fossa; from the fos-
sa 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  duode-
num.f

                    OMENTUM COLICUM.

  This is  a continuation ofthe  great omentum upon the right
side  of the great arch of the colon, where it rises from the ca-
put coli; but it  seldom extends its origin from the colon  the
length of the caput coli.   It is inflated with the great omen-
tum.

 APPENDICES EPIPLOICJE, OR OMENTULA 1NTESTINI CRASSI.

  These  are  little fatty and membranous  processes which
hang pendulous from the surface of the colon: they  are of the

 * Winslow, Duvemey, and Haller.
 + " Macilentius est, et vasa habet minora."  Winslow.  Haller. Indeed it seems rather
to answer tlie general purpose of a cellular membrane conveying vessels, than the purpof**
ofthe omentum majti--. 
196
OF THE  ABDOMEN.
tome texture and use with the greater omentum and right co-
lic 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 ofthe  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.J
   The use assigned to the omentum of  being subservient to
the function of the  liver is  deservedly neglected.^
                       CHAP.  II.
                             4

            OF  THE VISCERA  OF THE  ABDOMEN.


JH.AVING 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 sui-vey ofthe 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 works on anatomy.
   1. The membranous viscera, viz. the stomach, the  small
and great intestines, the gall-bladder, mesentery, the  mesoco-
lon, and  ligamentous processes, and the omenta.

  * Haller Element Physiol, torn. vi. lib. xx. $ 2 and 3.
  +Yf mU8t not suPPose hecause a madman stabs himself in the belly, and there is after
wards found coalition of the intestines to the wounds, the omentum has not done its office,
(see Boerhaavii Prelectiones, vol. i. $ 45.) no more can we give credit to the tale told by Ga-
len (De Usu Partium, 1. iv. c. 9.) of the gladiator who lost part of the omentum, and eve,
after had a coldness in his guts.' at least we cut out n great part ofthe 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, &r.      •
Moreagm Adversar. 111. Animad. VI.
  j Viz. by supplying a gross oily matter to the venae porta. 
OF  THE ABDOMEN.
197
  2. The solid  viscera, viz.   %he liver, spleen, pancreas,
the kidneys, and renal capsules,  the  mesenteric glands; but a
natural order in the arrangement of these viscera is to be pre-
ferred.
  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 cavaties; while
the liver, spleen, pancreas,  arid 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 sto-
mach, the small intestines, the great intestines.  The small  in-
testines are subdivided into the duodenum, jejunum, and ileon.
The great intestines are subdivided into the caecum, colon,
and rectum.   The stomach is the seat of the digestive pro-
cess :  in the duodenum the food receives the addition of the
secretions from  the  liver  and  pancreas, and is still further
changed ; in the  long tract of the jejunum and ileon the nutri-
tious part is absorbed;  and in the great intestines the foul  se-
diment becoming faeces is carried slowly forward, suffers a fur-
ther absorption of fluid, lodges in the lower part ofthe 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 
lyy
Oi  THE U2SOPHAGU3.
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 (ESOPHAGUS,

   I he 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 ofthe thorax, it perforates the diaphragm, and expands
into the upper orifice ofthe 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 tbe tongue  behind the isthmus fau-
cium.  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 ofthe oesophagus; its muscular and internal
coat: for  that  which is  sometimes considered as the  outer
coat, is only the adventitious cellular membrane, and the ner-
vous coat is merely cellular tissue connecting the muscular and
inner coat.
  The muscular coat ofthe 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 
OF THE  OESOPHAGUS.
I'M*
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. de-
glutition.f
  What is called the  tunica  nervea is  the cellular connec-
tion betwixt the muscular and inner coat, and  is very lax, in-
somuch 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  particularly
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 res-
pect resembles the lining membrane ofthe mouth.  The power,
however, which the oesophagus  seems to possess of resisting
heat depends not on tbe insensibility bestowed by the cuticle,
but is owing to tbe 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 vetebra?
and the trachea, but is at the  same time in  a small degree to-
wards 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 ofthe  relation  ofthe 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 bi-
furcation ofthe trachea and the arch ofthe  aorta, when it de-

  • It appears that the oesophagus can be ruptured  in two ways : across, by the tearing of
tlie longitudinal  fibres; and longitudinally, by the separation of the longitudinal fibres.
This, though a rare accident, takes place in violent vomiting or  straining to vomit; and, in
the first instance, the tearing across of the (Esophagus seems to be the effect of the action of
the diaphragm on the (Esophagus. By this accident the fluids of the stomach are poured into
the cavity ofthe thorax.
  + See farther ofthe muscular coat ofthe intestines.  " It was at one time suppow J mat
the muscular fibres of tbe oesophagus had a spiral direction."  See Verheyn, and M<vgan.
Adverear. iii. 
200
OF  THE STOMACH.
scends farther upon the dorsal vertebrae, 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 Vesalius to be-
long to the oesophagus. 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 ofthe glands going to open into the oesopha-
gus.  These  glands in the posterior  mediastinum are some'
times 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 mark-
ed by so very abrupt a line, as sufficiently to indicate that the
fluids poured  out  from  the  oesophagus are very distinct from
those ofthe stomach, and have probably no digestive property.


                     SECTION II.
                     OF THE STOMACH.

   The stomach is  that capacious  membranous  bag into
«vhich the oesophagus delivers the food, and m it is performed
the process  of digestion.  The food of animals is of various
kinds, and the form and structure ofthe 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  muscular
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 opera-
tion of the digesting stomach or true stomach.   The human
stomach is simple compared with the stomach ofthe herbivo* 
OF  THE STOMACH.
,201
rous animals, but more curiously guarded to retain and fully to
operate u. on the food than tbe 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
ofthe liver is betwixt it and the diaphragm.   On the lower
part it is, by the mesocolon and arch of the colon, divided-
irom 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 oesophagus ex-
pands; the lower or pyloric orifice, which leads into  the
duodenum; the lesser  and  greater curvatures  ofthe
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 tbe small central lobe of  the liver,  while there is attach-
ed  to it  the lesser omentum.  The greater curvature of the
stomach  is the outline of its distended belly, which rises above
the arch  of the  colon, and is marked by  the course  of the
gastro-epiploic vessels.
   In  the foetus,  the stomach lies  more perpendicular than
transverse.  In the adult,  when tbe stomach is distended, the
lower orifice is nearly on a level with 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
tendjng  obliquely downwards.  The ensiform cartilage will be
   vol. hi.                  C c 
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
 utnbilicalis of the liver:  the upper orifice is kept constantly in
 one place from the stricter connection of tbe 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 tbe  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 discharg-
 ing its contents  when  greatly  distended, the orifices being
 in  a great* measure  turned  from  the  oesophagus and  duo-
 denum.
   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 from 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 will 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 we  shall commonly observe in the  dead body.
 But sometimes I have found the stomach divided into two sacs,
 and more frequently  have 1 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.

   * Thus the gastroepiploic artery presents directly forward.  It has been wounded, and
 bled iioth into the stomach and outwardly. I should conceive it possible in such a case to
 to tie the artery.
  + "Wiuslow. 
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 musculur
contraction.  He is of opinion that the cardiac and pyloric por-
tions, thus divided, perform distinct offices.
             OF  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, how-
ever, L see no use, nor are they  authorised by the natural ap-
pearance of the coats of the stomach.  When there is a dis-
tinction 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 ofthe stomach do  not  run in an unin-
terrupted course,  but split, rejoin, and form a kind of retifortn
texture, through which the coats  beneath are at intervals dis-
cernible.  This structure  would  appear to bestow a  greatev
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 cir-

  * The most general opinion is, that tliere are three layers of fibres in the stomach. Some
describe an external longitudinal series; a middle transverse stratum: and again the inter
nal fibres running longitudinally.  See Galeati Acad, de Bologne.
1 
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 tbe cardiac
orifice, and may be 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-
cature 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  notion to its
contents.   But regarding the extreme sensibility of the sto-
mach, and the gradual and regular succession of action, much
will he found  that is  worthy  of attention!.   ^ 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, tbe mus-
cular fibres  of the upper part ofthe 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.
  t See Haller's Experiments.  Opera Minora, Ventrictilus Motets peristalticus. 
OF THE STOMACH.
205
set of 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 tbe 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 ofthe stomach hurting the coat; if there
be pain when the stomach  is full,  or at regular period   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 ofthe 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 ofthe stomach has a power of contraction on un
usual stimulus applied.  Haller loc. cit. Exp. ccciii. 
206                OF THE STOMACH.
 and nature has secured the end by combining tbe 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 i i>kj common disorders ofthe sto-
 mach.  We  shall find the  meteorismus ventriculi  (the great
 distention ofthe 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
 the stomach  and oppressing its functions lor days, while food
 more  recently  received  may have  undergone  the  actual
 changes, and have passed through the pylorus into tbe duode-
 num
   Owing  to the same slow and  successive action of the sto-
 mach, it often happens that ulceration and scirrhous pylonn, or
 other obstruction of tbe  lower orifice of the stomach, is atten-
 ded with pain, nausea and vomiting, only  at stated intervals
 after taking food ; i.  e. at the lime in which the food should be
 sent into the intestines in the natural course of action.
   1 he  muscular fibres of the stomach are excited by stimuli,
 applied, not  to their substance, but to tbe contiguous coats;
 and betwixt the delicate surface of the inner coat and tbe mus-
 cular fibres there is the strictest sympathy and connection.  ' he
 same connection holds in  a lets intimate degree betwi.t the
 outer coat and tbe muscular fibres; for when a part on tbe sur-
 face ofthe 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 ofthe 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 easede qua tangitur, contrahitur, sulcusque profundus nascitur, et rugae; cibusque
aliquando propellitur ut a stde-. contracta fugiat.  Mmus tameo quam inte3tina ventriculus
"tritabilis est: nine emetica fortiora necesse est purgantibos."—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 ofthe pyloric orifices in retain-
ing the contents of the stomach after the  oesophagus  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 lowerorifice
of the stomach of an animal yet warm, the fibres of the pylorus
were found to contract strongly upon it.  Upon forcibly com-
pressing 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 in tions, 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 the feelings of such men as chew the cud ; but it
happens that the best  recorded instance occurred in one,  a
mere  brute in intellect.f   Here the morsel was brought up
from  the stomach by  a very 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, Thes.
  An excellent plate ofthe Pylorus given with this Dissertation.—Mr>r%agni Adfrersar. III.
IV. do Ventricuh Struct.
  ■fc By .Sir Everard Homft. 
208               OP THE STOMACH.
         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 contend ofthe 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 unbj-Mhe  stomach from the
         upper portion of the canal: e£jj$0nhhe\.\es 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 of
         the abdominal muscles  and  diaphragm.  Such, for example,
         has been tbe opinion not only of J. Hunter, but of Duverney,
.        and of M. Chirac in Hist, de l'Acad. de Sciences,  1700.   M.
foys^iflJiWve 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

           * See Wepferde Cicuta Aquatica, p. 68.—Sauvage'g Vomitos. 
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 ofthe 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 by 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 resiting 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 ofthe sympathy betwixt
the upper orifice of the stomach and the diaphragm, by which.
a kind of weak spasmodic action is excited  in it, but without
a concomitant inverted action in the stomach and oesophagus. ■ »• •-*;• >\
It is a convulsive  aud sonorous inspiration, owing to an irrita-    *"  **
tion of  the upper orifice of the stomach and oesophagus, hut
not exactly of that kind which  causes inversion of the natural
actions  of tbe  stomach.  Thus we have  the singultus from
gluttonous distention of the  stomach, from some medicines
   vol.  iin                    D  d 
210               OF  THE STOMACH.
and poisons, from some crude aliment, or even from some fo-
reign b>»dy sticking low in the oesophagus, or  from inflamma-
tion.  The bourborigmi and rumination seem  to be gentler in-
verted actions of the upper orifice of the stomach and oesopha-
gus, unassited by any  great degree of compression of the sto-
mach by the abdominal muscles and diaphragm.
  The full action of vomiting is preceded by inspiration, which
seems a provision against the violent excitement ofthe glottis,
and the danger  of suffocation from the acrid matter of the sto-
mach entering  the  wind-pipe ;  for by this means the expira-
tion and  convulsive cough accompanying  or  immediately fol-
lowing the action of vomiting, frees the larynx from the eject-
ed matter of the stomach.  But the action of the diaphragm
is farther useful by acting upon the mediastinum, which em-
braces the oesophagus, and no doubt supports  it in this violent
action.
  The subject is Very interesting, but I must enlarge no morr
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 third 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 cellu-
lar 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 demonstrote  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 tbe 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 are

  * To call it cellular coat, however, would be to confound it with the  three cellular coati
 generally enumerated by authors.
  t Winstow, sect. viii. p. 04. 
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 ofthe pylorus,  which, however, has no resemblance to a
valve in its  form or  action.  This ring  is not formed by 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, plica 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 ofthe human  stomach are very small, but in
great numbers around tbe  termination ofthe  oesophagus.   In
this description I am looking to the plate of SirEverard Home.
Brunner described the glands ofthe 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, (Hal-
ler.)  But it is to Sir Everard  Home that we owe  the  most
careful observations on this subject.   His lectures on this sub-
ject delivered in the College  of Surgeons had that grave cha-
racter of investigation befitting the place, while they possessed
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-
larding putrefaction and dissolving the food.   It acts on those
substances which are nutritious to the animal, and which are
peculiarly adapted to its habits.
f These lectures are now publisher"; 
212               OF THE  STOMACH.
  It seems to be a peculiarity in the human stomach, that it
has a greater  capacity for 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  secundinesf   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 ofthe nature ofthe 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 enquiries, and brought  back to the consideration of this
living property, which can so accommodate itself to the nature
ofthe 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 ofthe stomach are then poured
out unmixed  with food.f   Although by these means a fluid
may be obtained which may properly be called the succus gas-
tricus, yet it must contain a mixture ofthe saliva, and secretions
from the  glands of the oesophagus  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 sufficieritlv
proved his minuteness and accuracy  of observation, lately told me that on tlie principle here
expressed he has been very successful in humouring the delicate stomachs of his patients: he
has  found that two  kinds of food received at once into the stomach will be reeded : when
separately, they will not disorder the stomach,
  f  See Observations on Digestion.
  | By Spallanzani. 
OF THE STOMACH.
213
a successful or uniform result.   And, indeed, chemistry seem?
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 it acts by corroding and  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 resistance
to its action inherent in a living part.J
   Mr. Hunter supposed it necessary that the animal should be
in health, immediately preceding death,  in  order that the se-
cretion  ofthe 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.
   Of digestion.—By  trituration  and  mastication,  and the
union of tbe saliva with  food in the  moulh, it is prepared for
the more ready action of the stomach  upon it.  No farther
change  is induced upon it than  the division  of its parts.   But
in the  stomach, the first  of those changes (probably the most
material one) is performed,  which by a succession of actions

  '" The mos:t curious fact is that property of the coats of the stomach, or of the fluids lodg
ing in the coats of the stomach, by which miik and the serum ofthe blood are coagulated
It has been found that a piece of the stomach will coagulate six or seven thousand times its
own weight of milk.  Thi* action seems a necessary preparation for digestion, which shews
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 tlie white of eggs
are first coagulated, and then pass through the process of digestion.  See J. Hunter, Animal
Economy, Observations on Digestion.
   + 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.
  X 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'.", of Glasgow, paper.  Ed'/
Journal, Ap. 1810-  Amonest other curious facts stated by Mr. Burns is this, that he h:<-
found all the length of the alimentary canal dissolved into a pulpy glutinous mass.  I mn;
say that, connected with the discussion, there  may enter a question as to what is the caus<
of a tenderness sometimes to be observed in all the membranes of the body.  I have to-da.T
examined the viscera of a negro, where the intestines were particularly tender, but the pen
• ardium and valves ofthe heart more remarkably so still. 
214               OF  THE STOMACH.
fits the nutritious matter for being received into the circulation
of the fluids ofthe living body, and for becoming a component
part ofthe 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 ofthe 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 tbe 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 ofthe 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 vermillion colour, and covered with
mucus and having certain plica.
   The vermicular undulations of these rugfe ofthe inner coat
ofthe stomach could be  observed.   Three or four hours after
this woman  took food, she fell an irresistible desire to raise
the dressings from the fistula.  Then flatus  was 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
of infusion of camomile,  she found perfect ease.  In the morn-
ing a small quantity of fluid  like saliva, ropy and clear, war 
OF  THE STOMACH.
215
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 breadth from the left extremity, or one third ofthe whole
length ofthe stomach distant from tbe 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 ofthe 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 ofthe 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 ofthe 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 ofthe 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
body and by perspiration, or when the  contents of the stomach 
21G
OF  THE STOMACH.
require to  be made more fluid—the more easily to suffer the
necessary changes of digestion.
   The change on the secretion ofthe tongue and fauces from
disorder ofthe 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 ofthe 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 disordered, 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 ofthe nerves; for we shall
find that this upper part of the stomach is provided in a pecu-
liar manner with nerves,  the branches ofthe 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, he.—and
again, the connection ofthe stomach with the animal economy,
as a whole,—must not escape  the attention of the student of
medicine.
SECTION III.
                   OF THE INTESTINES.

  That portion ofthe alimentary canal which extends from the
lower orifice ofthe stomach to the anus is called the intestines.
It is divided into the small intestines,and the great intestines;
the small intestines are divided into the duodenum, jejunum, and
ileon.   The great intestines are divided into aecum, colon, and
rectum.       g
  The marked difference of function is betwixt the small in-
testines and the great intestines.   But betwixt  the form and
capacity of the stoma'ch, 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 ofthe 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
ofthe 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 ofthe 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
©f the body while growing.
  In the carnivorous animal the whole of the canal is  shorter,
being about five times the length ofthe animal, for example in
the lion.  In the herbivorous animals the 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 the division ex-
tending from the orifice of the stomach till it is encumbered
in the mesocolon.   It is improperly called the duodenum.

                      THE  DUODENUM

   Stands distinguished from the general tract of the small in-
testines by its shape, connections and situation.  It has been
called duodenum,  because it  was usual to measure its extent
by the breadth of twelve fingers.   It is greatly larger than any
other part of the  small  intestines; irregular and sacculated;
more fleshy; and,  although it has fewer plicae, it is more glan-
dular and  more 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 pancreatiq
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 Everard Home's Lecture*
   vol. uu                E e 
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 duodehum 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  oft'
from it at other points, we have to remark the ligamentum duo'
dcno-renalv, Ugamrtttum duodtno-i-cpatician 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, while a greater profusion of cellu-
lar  membrane accompanies this than the other divisions of the
intestines.  The muscular coat is stronger than  that ofthe je-
junum and ileon ; the  plies formed by- the inner  coats, smaller
than those of the other part of the small intestine, and havino-
more of a glandular structure.  At the lower part of the firS
incurvation of the duodenum, the inner coat forms a partic»lar
process like to those which are called valvulee conniventes; and
in this will be discovered the opening ofthe biliary duct, within
which also the  ductus pancreaticus generally opens.
  It is not without some reason  that  anatomists have consi-
dered the duodenum as a second stomach, calling it ventricu-
lus  secundus,  and succenturiatus ; for there is here  performed
a change upon the food, converting the chyme  (as they have
chosen to call it,) which is formed in the stomach, into perfect
chyle.   But to suppose that the  chyme is  perfected in the
duodenum, is to suppose  the biliary and pancreatic secretions
necessary to  the formation of chyle ; a point which is not  al-
lowed ; for many suppose that the bile is merely a stimulus to
the intestines, holding a control over their motions; others,
that it is useful only  in separating Ihe chyle from the excre-
ment ; or again, that the bile is decomposed, part entering into
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

^raU&H? jt  " ,DteSlinum digiUle' vel inte*tinum rectum brevhsimum."  Advcrsar
nf^a/iS.rr&°f t^d"°'den,'»1 bi M. Laurent Bonazzoli, in the Transactions
sr^TiMr; M^caiisSr-L-claossen- **«w*-*««. *»■■ 
OF  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 ofthe 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 \}e the seat of uneasy and distressing sym-
toms.  We may observe that, from the course of the duode-
num, pain in  it should be felt under the seventh or eigth  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 irregula-
rities  of digestion affect the duodenum, and spasm and diges-
tion follow; the distention causes it to press upon the gall-blad-
der, and the pressure and excitement together cause an  irre-
gular 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 ofthe duodenum.
It may be of consequence to attend to this in the operation ol
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 ofthe operation  ofthe vomit.*
  From a defect in the natural degree ofthe 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 ofthe whole canal, and
inactivity of the abdominal viscera, because the peristaltic  mo-
tion is begun  here in the natural action of the intestines ;  and
if the  proper stimulus be deficient here, so must it be in the

  * Indeed vomiting in consequence of concussion and compression upon tlie whole contents
of the abdomen, and in a particular manner 00 the liver, affords most powerful means e.f
?;;<rating upon the infarction and reirrera of the blood in thr hepatic *vstem. 
 220         OF THE  SMALL INTESTINES.

 whole system of the viscera.   Hence the necessity of rousing
 the activity ofthe 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 observa-
 vation ofthe symtoms during life, that the study ofthe diseases
 connected with the duodenum  is the most important which can
 occupy the attention of the medical enquirer.*

                OF THE JEJUNUM AND ILEON.
                                       t

   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 umbilical re-
 gion.   The canal ofthe small intestines is gradually and im-
 perceptibly diminished in diameter as it is removed from tbe
 lev.r-r orifice of the  stomach;  so that the termination of the
 ileon in the caput coli is considerably smaller  than the duode-
 num.   This tract ofthe 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 ^ody, and ex-
 posed to  a surface amazingly  extended  by the pendulous and
 loose duplicatui es of the inner coat.  Here the fasces are  gra-
 dually separated  from the chyle, and  the chyle  adhering to
 the villi is absorbed and carried into the system of vessels.

   The jEJUNUMf 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
 ofthe  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  ofthe inner coat less conspicu-
 ous ; and the mucus 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 Hoffinan.
t So named from its being more generally empty 
OF  THE SxMALL INTESTI"NES.
221
may  be seen in my  Collection.  Sometimes  there is more
than one cfficum 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, and 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, tbe longitudinal muscular fibres will be found in gene-
ral attached to it.  Its use  is to give a smooth surface  and  to
strengthen the intestine, and in a great measure to limit the
degree of 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
the name of peritoneal coat.f
   The meseqtery is composed of membranes, glands, fat, and
the several systems of vessels,  arteries, veins, lacteals, and
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 mesentery,  reciprocally.  But at present we  may
trace  the mesentery from the root  of the mesocolon—for the
jejunum, emerging from under the  embrace ofthe 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 form 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 a wound, a por-

  » The appendices caecales ofthe ileon have given birth to a curious question in the patho
logy of hernia.  See " Hernia ab ilii diveru'culo."  Morgagni, Adv. Anat. HI.  "Hernie
forage, par l'appendice de Pileon." LErrnE, Mem. de l'Acad. Royaledes Sciences, an,.
1700; Ruysch, Palfin, &c.  See cases of anus at the groin in the Museum.
  + See Plate I. 5, 6, 7, 8. 
 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 INTESTINES.

   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
 ofthe muscular coat ofthe 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 debilitating illness,  with  scarcely  any  excitement  of
the intestinal canal, these fibres are  not to be observed.  In
 a  man  who has been cut suddenly  off by disease, or who
has died a  violent  death, they become more demonstrable;
and in diseases where there has  been congestion and excited
 action  in the  intestines, they are  of course still stronger and
 more  discernible.    The  internal stratum  of  the muscular
 fibres is much  stronger and more easily demonstrated.   Tbese
 fibres  will be observed much stronger about tbe duodenum and
 upper part ofthe jejunum, but-they become weaker and more
 pellucid towards the extremity of the  ileon.  Tracing any par-
 ticular 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
 surround the whole gut.*
   To account for that action of the intestines which urges on
' * Morgagni Adversaria Anatomiea III.  Animadversio V. 
OF THE  SMALL INTESTINES.
zm
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 direc-
tion, as was  asserted by Willi-,  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 ofthe gut by  the constriction
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 separately;
on  the contrary, excited  by the same  stimulus,  they have a
simultaneous motion to the effect 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 tlie acting of tlie longitudinal fibres in one portion of an intes
tine dilates that which i* below, otherwise than through the compression of food and flatus.
  f From the experiment of Haller and of others, it is proved that the irritability of the irt-
testines 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 th«'
stomach continues longer than that of the intestims. It is proved also that the action ofthe
intestine is adequate to the motion downward and the discharge of faeces, without the aid,
of tlie abdominal muscles. Sec Mem. par Halhr sur les Moutemens. des  Intestines,; and
Opera Minora, p. '39.3. 
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  yield 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 ofthe 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 mo-
tions 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 ofthe 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 retrograde  from  the same point of  the intestine
toward the stomach.*   And this observation, the exhibition of
medicine and the diseases of the  intestines confirm.  But far-
ther 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. eit, Exoer. 424 
OF THE  SMALL  INTESTINES.           225
   *Phe portion of the intestine included under A contracts and
sends its contents into B.  13 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 ofthe intestines.
   The stimulus to the intestines is matter applied to their inner
eoat: 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
terminate 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  ofthe 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
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

  * Haguenot gives an experiment illustrating the cause of ileus. He tied a ligature about
the intestine of a cat,  and found no antiperistaltic motion excited.  This is not wondei ful;
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 ofthe violent symptoms.  Many cases in the Museum
will give the  young student a correct judgment on this subject.
  Vide Scholium sub tit.  Calcu'us insignis Ilii. Observ. F. Biumi. Sandif. Thes. vol. Hi.
  t See Halter's Experiments, Opera Minora ; and " Dissections of the Atrophia  Ablacta-
torum;" with plates ; by pr. Cheyne.  Sandifort, vol. ii p. 381. in Pyf-nteria\—Ibib. V4 ■<
   VOL. III.                   F f 
226
OF  THE  SMALL  INTESTINES.
coining into play distends this, and undoes the intus-susceptio.
Bui  if the cause continues,  the  intus-susceptio is continued;
the included part ofthe 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  ofthe upper portion of the  intestine  ib often  in this v«ay
swallowed down  It is not however in the natural course down-
ward that this preturnatural action always proceeds ; fur,  as
the excitement is violent and unlike  the usual stimulus of fnod,
and as we know that an unusual excitement is very apt to cause
an inverted action, it often happens  that the intus-susception
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 ofthe gut are distributed.  It
might wiih 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, demonsirating 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 ofthe  mesentery as  considera-
ble  branches, but forming  in this coat many  branches, and
these subdividing, their extreme  branches are finally distribu-
ted  to  the inner coat.  This is  the  coat in which, in some
parts of the intestines, little glands <Jr cryptae are lodged.
                      VILLOUS COAT.

  The most curious part of  the structure of the intestines h
the villous or inner coat;  for by its influence "k> tbe 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 experiment to which Albinus attaches much importance. See also, in the Acad.
de Bologna, a paper by Mr. D. G. (ialeati on the fleshy coat of the stomach and intestine? 
OP  THE SMALL INTESTINES.
227
greater extent thin  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 valvule conni-
ventes.   Some of tbem go  quite round the inside ofthe  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 ofthe  stomach
irregularly, and tending to the  longitudinal direction ; further
down they become broader,  morp numerous, and nearly paral-
lel ;  they are of greater length, and more frequent in the lower
pan ofthe 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 val-
vular 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 ofthe connection and the greater relative extent
of the inner coat, is apparent upon inverting the gut, and in-
sinuating a blow pipe under  the villous coat, for then you may
distend the cellular substance ofthe vascular coat so as entirely
to do away the valvula? 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 tbe 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 surfacAof 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-
tem.  The fluid which is supplied by the surface of the intes-

  * See farther of their structure under  the title ofthe Lacteal and Lymphatic Evntu,
 « here the subject of absorption and the stmcture of the villi is treated. 
"228           OF  THE SMALL  INTESTINES.

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 impossi-
ble to procure them separate.*
                           GLANDS.

   Anatomists have observed small mucous glands seated in
the idlular 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 secre-
tion of mucous  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,
1 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 esta-
blished betwixt tbe 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 ofthe villous coat of the
intestine, and in an animal killed some time^-fter taking food,

  * It has been supposed that the fluids excreted from the surface of .the intestines were fur-
nished by very minute foramina (which are visible by paiticular preparation) in the inter-
stices of the villi. See the letter of Malpighi to tbe Royal Society of London on the pores
of the stomach; and the paper by M. Galeali in the Bologna transactions on the Inner
Coat, which he calls tbe Cribriform Coat.  These pores according to Galeati, are visible
through the whole tract of the canal, and particularly in the great intestines.
  fPeyrus.  Biblio. Manget. Biunnerus deglandulis duodeni. Morgagni Adversar. A^
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 ofthe bile, and that the effect of it is to precipitate  the
effete matter;  but I am more inclined to  believe that it s 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   V
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,J
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 tfiis  portion of the intestine is into
the caecum, colon, and rectum.^

  * In  Mr. Cooper's lecTures in the College of Surgeons, this attachment ofthe chyle to the
villi was considered as a discovery.  But the statement will be found in former editions of
tin's work.
  t This turn ofthe colon from the right across the belly is flexura prima, superior dextra
hepatka. Soemmerring
 i Flexura secunda, superior sinistra lienalis.
  $ Some authors divide the great intestine  into six parts, enumerating the Ccecum ; pars
vermiformis ; the right: the left ; and thejtransverte colon j 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  ofthe 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 fa;ces
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 ofthe colon, on
the right side, and examining the opening ofthe ileon  into it,
we  see a slit formed betwixt two soft tumid plicae ofthe 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 ofthe feces into the ileon, though
not absolutely to prevent it, as we know from what is vomited
in the iliac passion.J   In the form of the opening of the ileon,
and in the broadness ofthe 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 ofthe ileon into the colon, so
as to approach to that  structure  which we see in the entrance

  * Valvula Coli or Valvula Bauhini or Valvula Txdpii.
  f Of the opening of the small intestine into the greater,  see Morgagni Advcr.-nr. iii.
 Anini.-d xi
  J. Morg. Advers.  A. iii.  An. ix.  Kertkringius Observ. xxxi. 
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 fr.-. na 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 ofthe colon, and which, from its
action in guarding the ileon, might rather be called the valve
ofthe 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.

                          CffiCUM.

   Wk have seen  that the ileon is inserted into the side ofthe
colon : now that  portion of the gut which is below this union
ofthe 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 VERM1FORMIS.

   There is appended to the  ccecum 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 tbe great intestine, and stands off obliquely, so that some-
times its inner membrane takes the form  of a valve.|   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 feces.  The ccecum and appen-
dix in the human subject are just sufficient, like the form of

  * Animad. xiii                                   t Window.
   Morgagni. M. Laur.  Bonazzoli in the Acad, of Bologna. 
23*2          OP  THE GREAT INTESTINES.
the teeth, the stomach, and the intestines, generally to show
that man holds an intermediate condition among graminivo-
rous and carnivorous animals. The ccecum is one ofthe 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 cceca are long.

             great divisions of the  colon.

   The great divisions ofthe colon are these : First, the right
divisi w of the colov 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 colonj 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 ofthe 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

  * Colon transversvm.  Zona Coli.
  •(• For the varieties in the situation of this intestine and the viscera in general, see Mor-
jngni Adversar.  Annat. ii. Aniundver. ii.
  {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 ofthe inner coat are smaller ; indeed betwixt the vil-
lous coat of the  ileon  and the ccecum there  is a distinction
abruptly marked ;* 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 for-
mer   The cells of the colon being formed betwixt the liga-
mentous-like stripes which run  in the length of the gut, have
a regular threefold order.   These cells give lodgment  to the
faces ; retain the matter; and prevent its rapid descent or mo-
tion to the rectum.   Here the fluids are still more exhausted,
and the  ftces  take often the form of these cells.   When the
great intestines are torpid, and inert in their motions, the faeces
remain too  long in the cells of the  colon, and become hard
balls or scybalae.  But  when in this  state of costiveness the in-
testines are  excited by medicine, not only is the peristaltic mo-
tion of the  intestines increased, but the vessels pour out their
secretions,  loosening and  dissolving the scybala?.|
                      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  peritoneal 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.
                                                          p.
  * Vide Albin. Annol. Acad. 1. vi. c. viii. de intestinis et tab. ii. f. vii.
  f See note of the pores ofthe intestines.
  1 Stratum liberum, stratum omentale & tertium mesotolicum.
  (} See Morgagni.  See also Galeati on tlie fleshy coat of the stomach and intestinej, in the
Memoirs of the Acad, of Bologna.
   VOL. III.                   G g 
2Si
OF  THE  GREAT
INTESTINES.
                         RECTUM.

   The rectum* forms  the  last division  of the great intes-
tines ,  and I know no better proof of the impracticability of
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 saenim,
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 sa-
crum (a little to tbe 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 part 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
lleshy bands of the colon, spreading out, are continued down
upjbn the rectum in an uniform sljealh 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  ofthe 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 anatomist* who described from brutes. A Pro-
fessor of Edinburgh calls it eurvum, but this I cannot admit after reading Morgagni Epist
Anat \iv.                                            ° *   r
  t Winslow.
  X The presence of stricture within the anus seems to have given rise to conversation abnu*
i 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 tin- useless part of the food, that the matter  descending
th'ough the small intestine may not  as frequently be voided.
In the next place we see, that in proportion as the quantity of
UV 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 of
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  sope
other animals, being of a form calculated to retain the faeces,
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 of
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 faices 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 of the  bowels, this
                 * Sir Everard Home's Leclpres. 
266
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.
w
CHAP. III.
 OF THE SOLID OR GLANDULAR VISCERA OF THE ABDOMEN.


 J. HE solid  or glandular viscera of the abdomen  are the
liver, the spleen, the pancreas, the kidnies, the glandulae 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 res-
pects 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 a 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 ofthe 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 hepatica, carrying this blood
formed  in the liver to the centre  ofthe system : and  through 
OF THE LIVER.
231
the veins tbey supposed the blood to be carried to the remote
part of the body.
  The liver is the largest glandular body ofthe 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
ofthe abdomen, under the margin ofthe 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 proportoin of it found in the right side.
  Without going into the more minute subdivisions of this vis-
cus, 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 tbe margin of the ribs, unless near the pit of the stomach,
but in the foetus and child it is much  otherwise.  In a foetus 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 af-
firmed, 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 ofthe chest.  This enlargement
of the liver, and consequent descent of its margin, is to be felt
more easily by grasping the integuments ofthe belly, as if you
expected to lift up the acute edge ofthe liver, than  by press-
ing 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
OF 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 ofthe 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.   f'ut 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 close
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 by
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 ofthe 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
ofthe 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 dorsum! of the liver.
This ligament is broadest where it passes down from* the point
ofthe sternum to the fossa umbilicalis; but as it retreats back-

  * Ligamentum latum suspensorium, falcifofnie
  ■*• 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 fossa 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 ofthe foetus*
   The  coronary  ligament of the  liver is formed in conse-
quence ofthe attachment  ofthe liver to the diaphragm.  The
attachment is of course surrounded  by the inflection of the
peritioneum from the diaphragm to the liver.   It is called the
coronary ligament, though it has been observed, that this at-
tachment 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 diaphragm, 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
oreat division of the liver is marked on the convex surface by
the broad ligament; which running back from the fossa umbi-
licalis divides it into the two great lobes, the right and left.
When the concave surface ofthe 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. 171. and plate, p. 173. 
240
OF  THE LIVER.
   Lobulus Spigelii.*—The lobulus Spigelii is betwixt the
 two greater lobes, but rather belonging to tlie 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 si-
 tuation is within the circle or bosom of the lesser curve  of the
stomach.
   Lobulus caudatus.-}-—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 vena; portarum  and the  fissure for  the lodgment of the
vena cava.
   Lobulus anontmusJ 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 ofthe right lobe  there may be observed two slight exca-
vations, formed  as it were by the pressure of the colon and of
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 portse.   The back part of this fissure gives lodgment

  • Lobulus posterior—posticus—papellalus.         f Processus caudatus.
  X Lobulus accessoriu?—anterior—quadratus.
  "• Horizontal fissure, fossa lonjitudinalis, longa, anterior. 
OF  THE  LIVER.
241
to the ductus venosus in the foetus.  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 the lo-
bulus Spigelii and lobulus quadratus ; the processus caudatus,
and the lobulus lobi sinistri.   It is in this fissure that the great
transverse division ofthe vena portse 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 ven.e 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 porta?; the arteria hepatica; the venae ca-
vae hepaticae; the lymphatics ;  and the biliary ducts.| These,
with the nerves, form a very intricate system of vessels, brit 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
view  of their origin and course.
                     the vena ports.

  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.
  + It is generally called, fovea feltis or vallkula vesicuUrfellase.
  X And we might add, the arteries of the outer membrane of the liver which arise from the
mtcrnal mammary, phrdnii:, epigastric, and even the spermatic arteria
  v#l-.  in.                   Hb 
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 portae takes its origin from
tbe extreme branches ofthe coeliac, upper and lower mesen-
teric arteries.  The roots of the portae answering to  these ar-
teries  are  the splenic veins;  the gastro-epiploic  vein which
runs upon the great arch  ofthe stomach ; the mesenteric vein
returning from the small intestines ; and the right and middle
colic veins, and internal haemorrhoidal 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 ofthe vena portae is  now involved
in the irregularly reticulated web 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 porU 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
thejvena portae. Of these  two great brandies ofthe vena portae
within the liver, the right is greater in diameter, but  shorter :f
it ramifies  in tbe great right lobe of the liver.   The left is
longer considerably,  and  filling  tbe transverse 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 tbe peritoneal coat.  The

  * Sometimes it has been found divided before entering {he liver. It has been also found
to divide into three branches, in which cases, says Haller, two go to the leftside.
  f Into this branch sometimes the vein ofthe gall-bladder enters. 
                    OF THE  LIVER.                 243

blood of the vena porta? is received into the extremities of the
venae cavae hepaticae.
                    ARTERIA HEPAT1CA.

  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 venic 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.
                 VENJ2  CAVJE 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 tbe back part of the  liver for the transmission of
the vena cava abdominalis.  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 venae cavae 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 dia-
phragm 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 ga-
thered together from all parts of the liver in two, or sometimes
three great branches.
  The communication betwixt the vena portae and the vena
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 of the body betwixt the ar-
teries and veins; a circumstance which appeared to them the
more necessary, considering the lesser impetus with which the
blood flows in the vena porta? than in the arterial system. 
244               OF  THE LIVER.
                     BILIARY 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 and 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  porta?.
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.

               * Explanation of the plate of the gall-bladder.
              A The gall-bladder.
              B The cystic duct
              C The hepatic duct.
              D The common duct.
              E The hepatic artery.
              F The cystic artery  conring-oflF from  it. 
                    OF THE  LIVER.                   245
                     .*.  *   *  •  ♦   •
  The hepatic duct, after being joined by the cystic duct, con-
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 ofthe 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.
                         GALL-BLADDER.

  We have already noticed, that the gall-bladder is attached
to the lower surface of the right lobe of  the liver, and partly
buried  in  its sinus: it  has sometimes occurred that  it was
merely suspended to tbe liver by a membrane like a mesentry.
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 ofthe 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  musclar fibres in
the composition of the coats  of the gall-bladder.   This coat
gives form, limit, and strength to the gall-bladder.   The third

  * Ductus choledochus, 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 tlus is rather to be considered as growth  and enlargement, than distention.
  X 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 L1VLR.
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 ofthe internal membrane,
are of considerable variety  in shape, square, round, or triangu-
lar.  These rugse, 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 muGous folicules 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 rugse assume a semilunar figure, and seem to have a valvu-
lar action, in at least so far that they seem  intended to give a
degree of difficulty to the passage of the bile. The same struc-
ture ofthe 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 suf-
ficient 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   -
ofthe bile in the gall-bladder, or  a wise-provision of nature, I
am uncertain; but it appears, that the longer  tbe 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 
OF  THE LIVER.
247
place in consequence of the activity of the lymphatics, which
ramifying on the coats absorb the thinner part ofthe bile.
  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 confident-
ly affirm, that as tbe aliment passes tbe duodenum, the bile fol-
lows apace, eitheffrom the alternate contraction and relaxa-
tion of the duodenum  occasioning a relaxation of the orifice
of the ducts, or more probably from the ducts  being  excited,
as the salivary glands are  excited by the presence  of sapid
bodies in the  mouth.  By  want .and hunger, on the contrary,
the gall-bladder is allowed to be distended: there is no call for
its evacuation.                     ^
  Experiments would even teach us, tjat 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 dis-
tention.
  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 blows 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 be-
comes thick in its coats.
  The retention of  the bile,  surcharging  the ducts, and  dis-
tending the gall-bladder, and the sudden discharge of accumii-
* Anat. generale de Xav. Bichnt, torn. iv. p. 6. 
248
OF THE LIVER.
lated bile, and the irregularities of its course when influenced 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  ofthe peculiar proper-
ties inherent in the living fibres, that no transudation is allowed ;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.

           OF  THE MINUTE STRUCTURE OF THE LIVER.

   The liver is firmer and dryer in some  degree than any of the
other viscera; the intertexture of  membrane  is weak, and  in
consequence the substance ofthe liver is friable and easily torn.
When cut or torn, it  seems for tbe  greater part vascular : or it
displays the mouths of enumerable ducts and vessels, and, af-
ter a minute injection, tqe blood-vessels seem to pervade 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 tne vena

  * We have example of this in a Treatise on the Diseases of the Bowels of Children, by
Dr. Cheyne.
  t 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 hand-
ling the intestine in the operation for hernia?, the bad smell does not attach, nor is it Rt all per-
ceptible. Poison in the stomach of an animal will pervade the coats and affect the wholfe
substance, if permitted to remain after death: but if the  stomach containing the berr'e* of
the  laurus cer. be taken from the pheasant of America, they are wholesome food.  '1 he
peccary, or Mexican hog, when killed, must have the dorsal gland immediately cut out, or
the disagreeable smell o? this secretion makes the flesh unfit to be eaten Fcr the «aa.f rea-
son 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 Adverear. An. iii. A.
•a. to sxvii. 
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 ofthe body of tbe 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 ofthe 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  partae  : that the branches ofthe vena portae had a dou-
ble termination :  that some of them, by a sudden turn and ser-
 entine course, terminated in the  branches of the vents cavae
 epaticae  ;f while others were seen to terminate or open into
the biliary ducts.  Further he observed, that in all the branches
ofthe vena porta? there was a peculiar compressed appearance
which distinguished  them  from  all the other vessels of the
viscus.
   There  have  been  observed intersections of  the intimate
membrane of the  liver, which divides and subdivides the fasci-
culi of  vessels.   These are, however, somewhat obscure and
indistinct.  The last perceptible subdivisions ofthe substance
ofthe liver have  been called aciniJ; and they are rather pre-
sumed  than  directly  proved to have in their  composition an
extreme ramification  of 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 bilarii took their origin.   In this opinion he was  success-
fully opposed by  Ruysch, who affirmed that they were vascu-
lar ; and  in this opinion he has been supported by Albinus. It

  * Soemmerring.  Walther, loc cit. &c.
  11 should imagine that in this he might have been deceived by the lesser branches ofthe
portae (filled with injection) opening into the side of the largeT 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 rejicit, ne Ruyschius quidem, sed de interior febrica disputatur.  Hdlltr,
   VOL.  III.                  I i
I 
250                   OF  THE  LIVER.
would in truth appear, that the description of these partitions
ofthe substance ofthe 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 cel-
lular texture;  they may be called acini, according to the defi-
nition which has been given in the introduction.1*


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 1 am not satisfied that our knowledge  of its  functions is
nearly  perfect.   In  animal  bodies  one  organ  ministers  to
several functions.  As tbe  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 dis-
covering one use ofthe liver in secreting the bile  and stimula-
ting 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 tbe  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 diutius tergiversark fateor ergo, quod, quando primo incipie-
bam me exercere in anatomicis, videbara tunc quidem, quod in jecore humane seostendebant
acinuli parvi irmumerabili numero, quae turn tempons appellabaotar glandule: nam nemo
cogitabat aliter sed inanet sola jjam haec questio, an acinuli hi bic herentes sint glandule sim-
plkassime, foliculi cavi cum emissario an quid aliquid ?  dico nemo demonstravit  illos tales
esse ut hie as-umis.  Imo vero facile jam erit demoostrare, acinos hos cum criptis antea per-
tractis niiil commune habere:  quia oculis nostris non apparent ot memhranuke cavae & quia
etiam mm habent emissarium.  Sed componuntur tantum ex extremiUtibus ultimis vasculo-
rum sanguiferorum unitis in formam sphere rotunditatis, Deque, quantum possum videre
etiam membranula aliqua sua singulari circumambiuntur." 
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
 ofthe 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 ofthe
 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 function 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 necessa-
 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 Hie 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  s *nd off  smaller
 branches to supply the membranes and vessels of the lungs, it
 is necessary that for this purpose branches of the aortic system
 shall enter the lungs. Again, in the heart the blood contained
 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 vasorum  are distributed through
 the coats of the vessels. These vessels therefore bear an ana-
 logy 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 ves-
 sels 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 body : it 
262
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
hypochondrium.   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 of
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 body, 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 ah artery, prove the fallacy of this rea-
soning.*
  We may further observe on this case, that it doe% not prove
the bile to be the natural economy, secreted by the arteries
and not by the vena portae; for the  artery here was unusually
large, so that it performed a function in this instance which it
does not usually perform.  On  the  contrary, had  the  artery
been ofthe usual size, we  might then have concluded 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 dilated
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 motion checked
previous to its ultimate distribution.   Nay» it may have opened
into the branches of veins answering to the extremities of the
vena portae.
  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 this
opinion to be countenanced by the agjc-qliar circulation of the
blood  in the liver of the foetus, 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.

  * See Mr. Abernetby's case of uncommon formation of the liver. Phys, Transactions. 
OF  THE LIVER.
253
  I  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 porfce 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
port e 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.
  Tliere is another remark of Haller which deserves attention.
When I reflect, says he, that there is no bile required 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 umbicial vein  had
opened directly into  the cava, he thinks it would have returned
with  too great an impetus upon the heart, and would  bylts
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 LIVF.R.
 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, does not 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 loaded
 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 tbe 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 tbe 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 ofthe 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. 
OF  THE PANCREAS.
255
SECTION II.
                    OF THE  PANCREAS.

   The pancreas is  a gland the largest of those  which have
been called tbe conglomorated, 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 the two lamina ofthe
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 ofthe size of a writing quill. Towards
the right, tbe head of the pancreas is irregular, and indeed a
lesser pancreas geserally 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 retrogade into  the trunk of the pancreatic duct.
Sometimes there are two pancreatic ducts,  but more frequently
tbe part ofthe 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 Vimingi. 
256
OF  THE PANCREAS-
the dog there are distinctly  two ducts, tb.e 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 ge-
neral 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 peculia-
rity 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 anology 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 rarotid gland pours
out so great a quantity of saliva, says  M. Jlelvetius, 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 ofthe 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  discbarge of the
pancreatic Quid; 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 bf 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 tbe 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 ofthe intestines;  which seems to contradict the  result
of these experiments on  animals;  but by the scirrhosity and
enlargement ofthe pancreas the biliary ducts  may have been
more or less compressed, and the retarding of the  usual  quan-
tity ofthe biliary secretion might produce the slowness ofthe
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 ofthe pancreas was to supply an acid spi-
rit or juice, and the biliary secretion being of the nature of an alkali, these two strugjling
together caused the separation of the chyle from the feces.  The struggle did not stop here,
but these enemies being carried into the blood continued their warfare m the heart itself, and
lighted up the vital flame there.
  Nay, if we believe the experiment of F. Schuyl, (de Veteri Med.) this hypothesis was
not without its proofs: for having tied in the portion ofthe duodenum of a living dog, where
the pancreatic and biliary ducts enter, he saw the ebullition from this struggle ofthe acid and
the alkali; and wlien he compressed the hepatic duct,  the tumefaction ofthe intestine sub-
sided • 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 peristaltic motion
ef the  intestines.
   Vol. hi.                  K k 
258                 OF  THE SPLEEN.
                      SECTION  III.

                      OF THE SPLEEN.

  The spleen is a viscus of an irregular, oval figure, and dark
purple color.   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 be 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 hypothesis, and no-
thing is as yet certainly  known of its use.
                   SEAT AND CONNECTIONS.

  The spleen is seated in the  left hypochondrium ; above the
left kidney ;  and under the protection ofthe false ribs ;  and of
course it is under the edge ofthe 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 ofthe 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.-}-  After a successful injec-

  • Yet the  spleen is  very apt to change its situation, or to fall down from under the pro-
tection ofthe felse 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 variae. Albi-
nus Acad. Annot. lib.  vii. cap. xiv.
  11 have seen death  from rupture ofthe spleen, by a wound which never penetrated the
abdomen ; a  pistol shot entered the chest and struck the diaphragm without piercing it;
the lad died with effusions in the belly; and on examination, the spleen was found burst bv
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 of the spleen, assume a remarkably stellated appearance.
Upon the whole, this viscus has a resemblance to the substance
of  the placenta.  The spleen is seldom smaller than natural 3
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 vessels are suddenly fatal.f  Sometimes it is hard and
scirrhous : it is subject to inflammation, to ossification, and to
have tubercles formed in its substance. There is seldom sup-
puration in it.   The spleen has been observed to swell up and
enlarge  when  the stomach  is empty, and  to  be contracted
when it is full.  It has been observed, that it is large and spon-
gy 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 pe-
eular, insomuch that it does not coagulate like the blood in
the other veins of the body.J
   That which  more than any other  circumstance excites oui
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  then-
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
with nerves, but has very little common sensibility.   It has no
excretory duct.
   Professor Coleman  made experiments on dogs, and found
that when 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
spleen escaping from a wound bad  become gangrenous. He
could observe no effect to result from this extirpation.
  * For Verities see Morgagni Advers. III. Animad. XIX.
  f I have known a musketball striking the spleen but not penetrating the abdomen prove
 fatal in consequence of extravasation.
  } With regard to this point I have no opinion, having hitherto neglected to examine the
fact. The experiments of Sir Everard Home countenance the opinion. 
260                 OF THE  SPLEEN.
   Opinions regarding the use of the spleen.—Of the va-
 rious uses of the spleen, the lowest conjecture in respect to in-
 genuity 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 as-
 cribed to tbe spleen tbe 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 sit:"  or of
 "laughter holding both his sides," of which the holding ofthe
 sides was an evidence.   And again, since tickling the ribs is a
 demonstration ofthe effect from this excitement ol 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
 ofthe vena porta, replenished with the fat and oil of the omen-
 tum, it dilates that vessel, and prevents tbe stagnation and con-
 gelation of the blood.  In short, the spleen has been supposed to
 be subservient to the function of the liver, and to the prepara-
 tion of a watery (and sub-alkaline) fluid to the  blood of the
 portae.

 «tli«t S£« uIk'^ thiS liie ,0We^ in al™rditJ*- The spleen has been considered
 ^ n«,,^Lf ^f i.  "l! Ihf ST f ITreal appetite! the *?land which fo™ed the mucila-
 Klr   t/?^1 JSeat#?? received here"  concocted and transmitted to
 SntintpH A «T'*Krtb- "^ ^T"} U°^ fr°m ^ 8t°maCh' &C' °ther Pl^iologiste, not
 K?"!h    b the th?°T pTe5^>t^t0 tl,em' and yet incapable of suggesting othlrs more
 hKely, have very modestly asserted that the spleen was of nouseat all.
 exci£r&rR tel^eS|IidlU^e^flbrtu t>tilationi? nataoue in plurimis mortalibus risum
♦he left                 option is, that tickling the right side will do as well as 
OF  THE SPLEEN.
261
  Another opinion has been, that it counterbalanced the mass
.)f the liver seated to the right side ofthe 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 of
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  cceliac 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 SPLKEiN.
 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, when 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 bestowed by"the increased ac-
 tivity of tbe splenic artery.   When again the  contents of the
 stomach are fully saturated with the fluids from its coats, there
 is no longer an excited action of the splenic vessels,  and the
artery  terminating in tbe veins, the spleen returns the blood to
 the liver.   While the vessels ofthe stomach partake largely of
 the supply of blood, the arteries to the pancreas also  receive
 some increase of activity;  and even the blood of the vena por-
 tae 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 ofthe body ofthe spleen.

  * This has been supposed to be the effect of the impulse of Ihp hlrwl h..t nn*i,:..„   u
 more false.  Let any one examine the artery of a hmbwhen^ area! tS.™ I IZ? **
 the artery will be found  tortuous to supply it.  AraS in tte aneurismal S ShSTS* }
 is a breach in the arterv, and the blood finds a freeV ret "rn  to the K lEZJP*1* ^
found enlarged and tortuous in order to supply  helowe part of fhel&b^whK"*• **
 quantity ofthe blood withdrawn from the cZl\Lnby\R^Jc^oh with'fheTein.' 
OF  THE KIDNEY.
263
  That there are cells in the spleen is very generally believed,
and that some operation connected with the economy per-
formed there is  also a  general belief.   Sir Everard Home
was 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  THE URINARY ORGANS OF THE KIDNEY.

  The kidneys are distinct from those parts which have hitherto
engaged us,  as they secrete the urine, and form therefore the
link betwixt the viscera of the abdomen and those of the pel-
vis ; 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 enquiry ; because it
is the  field of dispute betwixt the contending parties regarding
the structure of 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
side ofthe 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
lower belly  of the  diaphragm;  which  last connection is the
cause ofthe 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 &-.y, behind 
264
OF  THE KIDNLY.
the peritoneum ; for  the kidney lying close upon the muscles
of the loins, the peritoneum is merely stretched over it.   This
is the reason why calculi in the kidney have wrought themselves
out by fistulae in  the  loins ;  and it is the ground of  the hazar-
dous 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 caecum 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  nephretic  cholic.
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, which is towards the spine and
great vessels, the arteries and veins and ureter pass in by the
sinus, round  which tbe 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 ofthe aorta betwixt the upper and the lower mesente-
ric arteries:  that of the left kidney has  its origin a little 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
right 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 producting  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 ofthe kidney,  however,
we must be aware that disease, inflammation, suppuration, nay

  * The vessels of the kidney vary greatly. C. H. Meuder de urinae excretiene, Sandi-
fort, Thes. Tiii.—Albinus Acad. Arraot. b. vii. c. v. 
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 ofthe
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 infuidibula.  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 saccula-
ted 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 de-
fend it from the acrimon;  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,-]- dropping deep into the
pelvis, and getting betwixt the rectum and bladder, they open
obliquely into the latter.J  The use of the ureter  is to con-
duct the urine  which is incessantly secreted^ 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.  Tbe 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 kidney dilated to
contain some ounces.
  f When the bladder is contracted in consequence of a  stone, or when it is dilated by ob-
structions, as from stricture, the ureters become dilated to the size of small intestines. Spe-
cimens may be seen in the Collection.
  X Nuck describes tlie ureters as being very irregular, and always contracted  in three or
four places.  Bartholin thought he observed valves as  the duct enters the bbdder, and
Coschwitz describes valves in their course.
  \ When a fistula of the loins commuuicates with the kidney the urine flows uninterruptedly

   VOL.  III.                    LI 
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 re-
fute 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 lobula-
ted;  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 dis-
tinct 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

                    * Explanation of the annexed plate.

  A n C J?*  T1)e fverai rdivisi?ns, of the kidneJ" wllich give it the lobulated figure.
  L  E. The cortical part of the kidney, being the outer, and, it is supposed, the secretins 
OF THE  KIDNEY.
26^
glandular part  E.  Secondly, striae, 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 these subdivisions.
Thus,
              A. A. Cortical Substance.      B. Tubular pari.
               C. Papilla.               D. Duets.

   The papilla C is merely the continuation ofthe tubuli B ;
but it is that part which  projects from the body of the kidney
into the calyx or infundibulum ; and although these divisions
ofthe 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 ofthe whole gland, the mouths
of some larger vessels may be observed betwixt the fasciculi

  F F.  The tubular part of the kidney.                .,..,.,    r.u   t-
  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.
  I I I.  Other papillae
  N. B.  This represents only one half of the kidney.

  * Imp-operly medullary, sometimes striata. Winslow (traile du Basventre) has these
distinctions of the substance or the kidney.  I. Corticale. 2. Cannclle, sillonnee, ou tn.
buleuse.  3. Mammelonn^e. 
268
OF  THE  KIDNE1.
of the urinary tubes, yet they are irregular ramifications tend-
ing to the outer cortical part, and not such as separate the tu-
bular 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 ofthe 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 ofthe colour ofthe arteries.   These are
the glands ofthe cortical part of the kidney, which Malpighi
described as hanging upon the branches ofthe arteries  like fruit
upon the pendant  branches, and  round which the arteries 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 very obscure.
   Ruysch and Vieussens held a  very opposite opinion regard-
ing the structure ofthe  kidney.*   Ruysch,  by throwing his in-
jections into the renal arteries, found that he filled the urinary
tubes, the ducts of Belini, and the pelvis itself.   Hence he con-
jectured that the tubuli uriniferi or excretory ducts of the kid-
ney were the  continued branches of  the renal artery, without
the intervention of any glandular apparatus.f

  * Ruysch and Vieussens long contended for tbe claim of the discovery of the continuation
of the arteries of the kidney into the urinary ducts. Ruysch at first acquiesced in the opi-
nion of Malpighi, as we have said.
  + Thes. Anat. Ii. p. 31. 
OF  THE  KIDNEY.
269
Example of  Ruysch's  doctrine.
Ruysch's Piatt
   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

   When after minute injection of the kidney  we  make a sec-


  • Exhibet renis human! dimidiam partem ita  dissectam, ut reptatus vasorum, presertim
sanguineorum, loculentius quam in precedenti Thesauro, tab. iv. fig. iii. videre possit; ubi
magis inherebam, ut conjunctiones arteriolarum cum ductibus Behni exhiberem, in hac au-
tem figura distinctissime vasorum sanguineorum cursum vermicularem per  interiorem renjs
partem exprimere volui.
  A. Fades renis exterior perquam vasa  sanguinea reptatnm observant vermicularem.
  B. Fades renis interior ubi vasa sanguinea non minus cursum  vermicularem observant
quam in facie exteriore.
  C.  Papillae renales.
  D. Pelvis renis.
  E. Cavitas pdvis iu quam papillae urinam stillando exprimunt.—See  Thesaur. Anat.
W. p. 27.
  f In hoc Thesauro X. quoque inveniuntur objecta renalia ex homine desumpta, in qui;
bus non solum luculenterapparet quid judicandum sit de-j-saetensis glandulis  renalibus, verum
etiam quid investigatoribus renum imposuerit, se in re?t*$is indagandis sspissime occurrunt
corpuscula rotunda  glandulas mentientia quae revera nil f flit nisi arteriolarum ultima? extre-
mitates contorts;  cum  autem exactissime repleantur arteria?  renales dissolventur vel ex-
panduntur, quemadmodum fili glomer, ita ut nil minus sint, sicuti dixi,  quam partes perse
subsistentes & peculiari membranula obducta? sine quo immerito dicuntur  glandulae.  Inte-
rim  considerandum ejusmodi contorsiones vasorum  sang,  nusquam in ceteris visceribus
icperiri.  In  the epist. to Boerhaave, p. 77., we find Ruysch sppaking much more modest-
ly :  " In rene humano rotunda corpuscula esse, fateor, sed sunt tarn exilia, ut nihil possim
dVfmirc de illis.  Adeoque non licet magisdicere quod sint glanduke, quam aliud quid." 
 270              OF THE  KlDNEi.

 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
 arteries.
   Winslow supposes the corpuscules, which are seen in the cor-
 tical part ofthe kidney, to be the extremities ofthe cut tubuli
 filled either with blood or with a coloured  injection.  But this
 they evidently are not ; for by making the substance  around
 them transparent, they are seen within the surface,  and  they
 are little  grains, not the extremity  of tubes, nor extended 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 was separated by a more per-
fect 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 corpf^jcules of Malpighi,  which he also con-
ceives to be the  extreithties of vessels merely. 
OF  THE KIDNEY.
271
M. Bertin's 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 acervulce of small glandular bodies
are as  it were laid in the tract from the circumference towards
6he 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 ramify
to great  minuteness, and accompany them where  they are re-

  * Mesches de  M. Winslow on  vaisseaux spongieuses de Viensjo.'!* on tnyaux serpenlnns
de Ruysch. 
272
OF  THE KIDNEY.
fleeted directly inward to form the tubuli.   Much ridicule, 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 tbe 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 finallv open into
the ducts of Belini at the point of  the  papillae.  The pa-
pillae we have seen to be that part ofthe pyramidal body which
projects into the calyces or infundibula, and from their point
little drops  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 minute  structure of the  glandular
visceral
                 OFFICE OF THE 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, we
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 sphosphoric salts, as phosphate of soda
* Of the kidney much in Morgagni Ad vers. Anatora. iii. 
                     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
 hody are preserved.


                 OF THE CAPSULiE RENALES.4*'

   The renal capsules are glandular bodies of a redish 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
 caeliac  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
 research,  and all is doubt and uncertain  speculation."];  For

1 • Glandulm nlrabilarioe, renes succenturiata;. Glandulm renales, tfc
 f For various authorities on the size and appearance of this body, see Morgagni Epist
 Anatom. xx.
 X Morgagni Adversar. An. iii.  A. xxxii. 329. Valsalva is reduced to the necessity of quo
 ting Scripture, and Morgagni is as much at a loss Epist. Anat. xx. being obliged to join in
 Hie words of Euitachius; "iis relinquamus, qui anatomen acuralns exercent, inquirendum."'
 \Iorgagni, loc. dt.
  vol. nr.                   M m 
274
OF  THE KIDNEY.
my own part I conceive that this body is useful in tbe foetus, by
deriving the blood from the kidney, that gland not then having
undertaken its proper office of secreting the urine. 
THE
ANA  TOMY
OF THE
MALE  PARTS OF  GENERATION.
 x\S there is no very accurate division betwixt the viscera of
 the abdomen and those of the pelvis; as the uterus and blad-
 der, being viscera of the pelvis, rise into the belly when dis-
 tended, and  are in every respect like the abdominal viscera,
 many have objected to a division of the viscera of the abdo-
 men 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 coc-
 cygis, and  ossa innominata,  and that anatomists have distin-
 guished the  true and the false pelvis.  The false  pelvis  is
 formed ofthe extended wings of the  ossa ilii, and supports the
 viscera of the abdomen.  The true pelvis consists of that ca-
 vity 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 vesiculae seminales, and part
 ofthe urethra.  In woman it contains the rectum, vagina, ute-
rus, Fallopian tubes, ligaments ofthe  uterus and ovaria.
  The manner  in which the parts ofthe male pelvis are con-
nected, and  the  anatomy of the  urinary  bladder,  prostate
gland, and urethra, will form the  subject of the first section ; 
376     OF THE  PARTS WITHIN  THE PELVIS.

while tbe- anatomy of the parts connected with those of the
pelvis in function, but seated without, will form the subject of
the second.
-~o*e»—
CHAP. III.
          .  OF THE FiTRTS WITHIN THE fELtlS. »


     E 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 cel-
lular membrane is the medium of adhesion here: the parts are
imbedded in cellular membrane which is interwoven with mus-
cular fibres towards the lower opening  of the pelvis^ and fur-
ther  braced by  tbe levator ani and muscles of  the perineum.
This gives to the whole due support; enabling them to resist
the compression and action ofthe  abdominal muscles, which
thpy 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 de-
fined ; 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 ii, and
rises inlo the abdomen.
SECTION I.
               OF THE BLADDER OF URINE.

  The bladder of urine must be classed with membranous 01
hollow viscera.  It is a bag or receptacle into which the uiinc
W 
              0F THE  BLADDER  OF  URINEs     ~    277
                                              C- ' •*"   **■ '*
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 tbe 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 ofthe commencement ofthe 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 ofthe pelvis.
   On the fundus there is a  ligamentous process, continued in
a direction towards the umbilicus; this is the uracus.   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
Gera, the bladder consists of several coats.
   The peritoneal coat ofthe  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. Thai
portion  of  the peritoneum which covers the back part  of the

  * Fernelius depart, morb. if symptom. |ivesan example of a man who, having an obstruc-
tion at the neck of the bladder, passed his urine by  the umbilicus. Wepfor gives a similar
rase of a man with calculus. These are quoted by Albinus Annot. Acad, and also the Philo?
Transactions, n. 323. See also Sandilbrt Thes. Vol. iii. p. 2W—2-16. 
278         OF THE  BLADDER  OF 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 ofthe 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 with 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 we 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
 -trong. Three  strata of fibres  are described by authors. They
 are so strong as to  have  been classed  with the  distinct mus-
 cles, and the whole coat has been called detrusor  urinje.
 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.""^
   Towards the fore and lower part of the bladder,  the mus-
 cular fibres congregate into a sort of tendon, which goes off to
 the back ofthe 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 we 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 power of contraction,  and
 often the young surgeon is deceived by what he  conceives to
 be an incontinence of urine, while it is really an obstruction.
   The true sphincter of the neck of the bladder has hitherto
 escaped notice, it has been looked for on the outside of the
prostate gland, and then the compressor prostata?, the levator

 * See description ofthe folds of the peritoneum.
 t Morgagni Adversar. Anat. iii. Animad. xxxix.
 t Some very remarkable examples of this may be seen in my Collection 
OF' THE BLADDER OF URINE.          279
urethrae, 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
  feneral surface, and is  bedewed  with  a sheathing mucus.
  Vlien 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 ofthe fluid evacuated  from the bladder.  No
visible source of this mucus is to be  observed on the inner sur-
face of this membrane ;* so that probably it is  a general  dis-
charge from the surface.  Indeed, it appears, that no  folicules
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 unne.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 ofthe coats is, that, the  greater the
tendency of the urine to pass retrogade 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, tliere 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 Heister and Haller describe folicules,
near the neck of the bladder, and round the insertion ofthe ureters.
  f When the mucous secretion is diminished by a disease of the inner membrane of the blad-
der, tlie calculous concretion more readily forms on the surface. 
280
OF  THE PROSTATE  GLAND.
   Corpora camea.*—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 tbe  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 ofthe 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.   It is
 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 tbe 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 Cornea Morgagni. Vide Adversar. Anatom. i. 9. A. iii. 421.  Mammeleon
 il'on^e Splanchnologie par R. J. C. de Garengeot.
 A ^p.c a paper by me on this subject in the 3d. vol. ofthe Medico Chirurg. Trans. 
OF  THE PROSTATE  GLAND.           #81
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 tbe urethra.   And behind this, again, he will feel the
prominence of the prostate gland, not round, distinct, and ac-
curately 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 folicules 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 shewn  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 I  can  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 Mirgagni Adversaria Anatomica, Animadwrsio XV. Prostate propago
   vol. iii.                N n 
282
STRUCTURE  OF  THE PENIS.
that this mucus serves to sheath the passages  and preserve
them from the acrid urine.  It certainly unites also to tbe se-
minal 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 ofthe spongy body ofthe urethra, and consequently
close to the membranous part ofthe 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.
OF THE PARTS CONNECTED  WITH  THE  VISCERA OF THE PEL-
  VIS,  BUT  SEATED WITHOUT IT.--OF THE PENIS AND URE-
  THRA.--OF THE TESTES.
SECTION 1.
OF THE PENIS AND URETHRA.
                 STRUCTURE OF THE PENIS.


 JL HE 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  tbe body ofthe 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 qf 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 distension 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 carver-
nous 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 connections 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 Tiody is not stag-
nant.
               Section of the penis, as inflated.
A, Corpus cavernosum Penis.  B,  Septum.   C, Urethra. D,
    Corpus spongiosum Minus, or spongiosum Urethrae. 
284         STRUCTURE OF THE PENIS.
  Corpus spongiosum urethrje.—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  o
the name spongy body of the urethra, or corpus spongiosum
urethra'.
  The spongy  body extends the whole length  of the  penis,
and where  it extends backwards into  the perineum, belwixt
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 an half of the lower part of the spongy body, that the
ejaculatorseminis or accelerator urinae acts; and, as within this
enlargement of the  spongy body which surrounds the urethra
tliere is also a  dilatation of the  tube of the urethra itself, the
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 tbe spongy body is
enlarged into the glans: thus forming the bulbous head ofthe
penis which crowns the conical  extremities of tbe 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 Ever-
aru 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 accelera-
tor, and the state of distention of the  spongy body, will have
this effect.
  The obtuse glans spread upon the extremities of the caver-
nous bodies of the  penis, has no communication with 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 little
glandular bodies.*

 * Glandule odorifera of Tyson. Sc Morgagni Adversar.  IV.  \niniad. XII. eticqutr.
tt" j-thrm.ii! CvrewKptnif. 
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 tbe 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 frenum preputii.
  The whole integuments ofthe penis are ofthe same cellu-
lar structure with those of the rest ofthe body ;  they are par-
ticularly  loose and distensible, and  unincumbered with  fat.
We may see  then in  emphysema and in  oedema monstrously
distended.
                    of the urethra.

   The urethra is all that length of the canal from the neck of
the bladder to the extremity ofthe penis.  It is formed ofthe
continuation ofthe inner and third coat ofthe 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 into the sinus of thk 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 tbe 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  glands which I have des-
cribed, there are large  lacunae observable; into which mucus

 * Haller Com. lib. xxvii. sect 1.1 xxx.  Mr. Home's Strictures, Obsery. de partlbus ge»
•)italibus?pxui«po(iori« Sandif. Thw. vfll. p. 71. 
286
STRUCTURE  OF  THE PBNIS.
is secreted, and  from which, as from receptacles, it is pressed
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 ofthe 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 ofthe 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 ofthe 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 ofthe 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 ofthe 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 Canalculi Morgagni, Advers. Anat.—De glandulis urethra? vide Mor-
gagni Adversar. IV. An. vii. et sequent.  There is much controversy and much confusion
regarding the gland ofthe urethra, viz. Prostata minora; glandular Cowperiancej glandu-
lar Littreana, #c. The reason of which I believe to be, that the lacuna do not appear glandu-
lar unless when they have suffered by inflammation, tliere is no round smooth body attaches
to them, unless their secretions  have been increased and the cellular membrane and vessed
ara condensed around the lacunas.
  t Morgagni describes the membrane of the urethra as double, having vessels betwiit its
laminae. These are the veins described by Dr. Barclay. Observ. Anat. P. I. tab. IV. J. C.
Brims, Sand. Thes. VI11., describes two lamina?, one of which he considers to be the con-
tinuation of the muscular coat ofthe bladder. 
STRUCTURE  OF  THE  PENIS.          287
width ofthe canal.  It is surrounded, as we have seew, irith a
spongy body and the cellular coat which is betwixt jfre deli-
cate lining membrane  of the urethra, and the spajjgj  body
partakes of  the structure of both, and is very eCstir;.  But
when an inflammation  attacks the canal, this  cellular rflem-
brane is its principal seat.  The point affected loses its elas-
ticity ;no longer stretches with the penis and urethra, but con-
solidates, or forms a strong membranous filament.  To sup-
pose this stricture to have been formed by the muscular con-
traction in the diameter of the canal, would be to allow the
partial action of one or two fibres; (for the stricture  is like
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 it 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 ofthe  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 was 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 tbe 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 urinae, 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  urinae, more properly the ejaculator seininis.  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 theirACtion when the canal is inflamed,  give occasion to
thofe contractions which are attributed  to the membrane of
the,urethra itself.
f" '


                     SECTION IL
                     OF THE TESTES.

  The testicle might be considered as more naturally con-
nected with the abdominal visdera, than with those ofthe pel-
vis, as its 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 : the^ 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
tlucts 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 trie water of anasarca -*4-
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.—The cellular substance of the scrotum is
peculiar in its appearance, being red and fibrous.   It has been
considered as a muscle, and called dartos ;* although this is
denied by many.   Its action is to support and brace the scro-
tum ; and in bad health,-}- 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 within, and  when
for some obstinate disease of the body ofthe testicle blisters
are applied to the  scrotum, we may see this muscle in great
activity rolling round the testicles.  The straight fibres of the

  * Aetfrcs Veterum.                               ,
  f Nurses attend to the state ofthe 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 ofthe scrotum, directly in the
middle, there is  a line passing from tbe lower part of the penis
to the anus;  the rapha.  This line.marks a division  in  the
scrotum, a partition, or 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 ofthe 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 ofthe 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 ofthe  peritoneum, even before the  coats ofthe 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 ofthe 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 operatic*
divided this into three lamina
  VOL. III.                    O  » 
299'                 OF  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 ofthe testicle.  Betwixt these coats
is the fluid collected, which forms the hydrocele.  They also
contain the congenital hernia; but the common hernials with-
out both coats of the testicle.  To understand the anatomy of
this part thoroughly we must  attend  to the descent of the tes-
ticle, 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 lodg-
ed in the  belly,  and are in every respect like the abdominal
viscera.   They are  seated on the forepart of the psoae mus-
cles by the side of the rectum.   They are covered and  in-
vested 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 substance
of the testicle is invested  by a coat, and that coat is the peri-
toneum, which,  after covering the body of the testicle, is re-
flected upon the loins; as  the  coats ofthe 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 un-
derstood 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 ii
apt to believe he understood the nature of the descent of the testicle.  Specilegium Anato-
micora. p. 35.
^ 
OF  THE TESTES.                 291
Pirst 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 tha^ this  last covering will 
292
OF THE TESTES.
come to 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 ofthe 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 i^
smooth, and forms no adhesion; whilst tbe 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
ofthe  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 ofthe Testicle.
id. Plan of the Testicle.              3d. Plan of the Testiole.
 
OF  THE TESTES.
298
   In the first plan we had the situation ofthe testicle in  the
foetus represented.   In the second plan, we have the middle
stage ofthe descent represented:  and, in the third, we 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 ofthe 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 recognize 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 ofthe 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 it? descent.
Fourth Plan of the Testicle.
G 
294
OF 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
 int»at»ne slipping down  from the communication b,etwixt the
 general cavity of the peritoneum, and the cayjy 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, tbe 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, (i. e. of the al-
 buginea,) by a portion ofthe 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 si-
 tuation 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,
 mingied 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 ofthe 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 \he 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
Tessels of the cord, before  the testicle has  fully descended, 
OF  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 ofthe 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 -
  £art, and then the whole extent of the passage  (viz. from E to
  >, in plan third of this series,)  is shut.   When this process is
prevented 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 ofthe tunica vaginalis, by fluids descending from the bel-
ly.  The character of such a tumour will be,  that the fluid  will
be easily forced into the belly.  It may be mistaken for a con-
genital 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
descends with the gut before the cord ofthe  testicle.

 • Mr. Hunter has shewn, that the detention of the testicle in the belly is in consequencejof
some defect and want of action in the testicle, and that those who have the testicle remain-
ing in the belly have it impeifect or small.  This is contrary to an old authority:—The tes-
ticles are seated externally, " for chastity's sake, for such live wights as have their stones hid
" within their body are very lecherous, do often couple, and get many young ones." 
296                OF  THE TESTES.
Fifth Plan of the Testicle.
  This 5th 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 ofthe coats of the tes-
ticle,) as is seen in plan -3d, open  from D to E, but forms a short
sac, surrounding the tunica  albuginea: D, the cellular mem-
brane ofthe cord of vessels  passing down to the testicle.  And
now there are no remains of 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 ofthe
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 faci-
litate 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 tunica
albuginea. For, as we have seen, that the same surface ofthe
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 water, from the ab-
sorption being disproportionate to the exudation.  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 tu-
mour, the opaque mass of the  testicle behind ; generally the
distended vaginal coat stretches up before the cord conically:
thus:
Sixth Plan ofthe Testicle.
Hydrocele.
VOL. III.                 Pp 
298                 OF  THE 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 tuni-
ca 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 dif-
ficulties will perpetually return upon  him. It is for this reason
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 enquire a little farther.
  When we dissect the  coats ofthe 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 co-
vered 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 vaginalis
reflexa ; 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 GraojjFspeaks of the division of tlie tunica albuginea into tiro membranes, probably
meaning to distinguish the cellular tissue of the body of the test'cle from the investing mem-
brane.  Morgagni in his commentary on him tells us he can separate the tunica albuginea
jitotro lamina, the inner of which was the most delicate. Advers. An. iv. Auimad. i. 
OF  THE TESTES.
299
  The spermatic  artery rises on one side frotn 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 sper-
matic artery, because there  is another which rises from  the
hypogastric artery ; this branch runs upward, connected to tbe
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 pyrami-
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-
pathise readily with each other.

  • Corpus varicosum,—Corpus Pampiniforme; Galen de Semine. Alias parastatam vari-
cosam, 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
 -hanged into semen,  and therefore they called them the vasa preparentia. 
300
OF  THE TESTES.
  The lymphatics of the  testicle are  numerous, and  easily
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 abdo-
men,  from tbe os pubis, and passing down over the vessels of
tbe cord, is expanded on the tunica vaginalis.  The use as-
cribed 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, drawing
it up,  and accelerating the discharge of semen.
  Thus we find the cord of the testicle, as it is called, to con-
sist of the excretory duct;  of the arteries, veins, and nerves;
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 fervor 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 xv&
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 more  modem authors.
  De Graaff,  by exciting the gland of brutes, and tying the
spermatic cord, Jbad  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 of  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 vessel*.  Bj 
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;
 for he, as we have said, saw this part only filled with semen.
   Connected with the  rete testis is the  corpus Highmoria-
 NTjm.—Where the lines of the membranous septa,  and cellular
 membrane  ofthe 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 High more 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 ofthe epididymis, and to form the communica-
 tion by which the semen flowed from the testicle.  De Graaff
 first refuted this notion, and shewed that it was not by this one
 great duct, but by these smaller tubes forming what has been
 now called  tbe 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  un-
derstood to arise from the tubuli testis; now it is the continua-
tion of  the rete testis  which is called  vasa efferentia.  The
vasa efferentia  are very delicate vessels which run out from
the head of the testicle, single  at first, but they are soon con-
voluted,  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 vas-
cular cones are connected  by a very delicate cellular mem-
brane ;  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
feeen called epididymis.

                 Seventh Plan of the Testicle.
  In this representation ofthe dissected testicle, A is the body
of the testicle divested of its coats ; B, the tubuli testis ;f  CC,
the rete testis; D, the rasa efferentia; E, the vascular cones;
F, the epididymis, formed  of the convolutions of the vas  de-
ferens ;  lastly, G is the vas deferens.

  * This body is called a merejirmamenlum or binding.—Winslow.
  t Where the tubuli are emerging to form th« rete vasculosum they are called the vasa
'>cta 
OF THE TESTES.
303
   In the substance ofthe testicle there are no glands nor foli-
cules ; tbe arteries minutely ramify amongst the seminal tubes,
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.  FronTthe 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  vesiculae 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 a power of accelerating the fluids through
them.
   There is a duct which sometimes arises from the epididymis,
and which we find  to terminate  abruptly in  a blind  end—of
this, Mr. Hunter speaks in the annexed  note.*
                of  the testicle  in general.


   The testicle is of an oval  form, and ofthe 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
lower, C.   The  spermatic cord  consists  of the artery which
brings blood; ofthe veins which return it;  ofthe vas deferens,

  * " By a supernumerary vas deferens, I mean a small duct, which sometimes arises from
the epididymis, and passes up the spermatic cord along_ with the vas deferens, and commonly
terminates in a blind end, near to which it is sometimes a little enlarged.  I never found
this duct go on tp the urethra, but in some instances, liave seen it accompany the vas deferens
as f.r as the brim ofthe pelvis. There is no absolute proof that it  is a supernumerary vas
defe. ens; but as  we find tlie ducts of glands in general very subject to singularities, and  that
there are frequently supernumerary ducts, there being often two ureters to one kidney,. some-
times distinct from beginning to end, at other time; both arising from one pelvis; these ducts
arising from the epididymis, 1 am inclined to believe from analogy, are of a nature similar to
the double meters.  They  resemble the vas deferens, as being continuations of some ofthe
tubes of the epididymis, are convoluted where they come off from it, and afterwards become
a straight canal passing along with it for some way, when they are commonly obliterated.
  " The idea of their being for the purpose of returning the superfluous semen to the circula-
tion is certainly erroneous, from their bein» so seldom met with, and so very seldom conti-
nued further than the brim of the pelvis." Many examples of this may be seen in my Collec-
tion, 
304
OF  THE TESTES.
which carries the semen to the vesiculae 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, itjis essen-
tially necessary to attend to the relation of the parts of the tes-
ticle as felt through the scrotum.
Eighth Plan of the Testicle.
   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
f epididymis, orthe large head of the epididymis :* then we see
 it laid along the back of the testicle, and observe C to be the

                      * Globus ?najor, or head. 
OF THE TESTES.
305
small head ofthe epididymis,* where  the tube  is reflected to
re-ascend upon the testicle, and to form D, the vas deferens.
  Now, we have  to observe, that  the  point C, fig. 2. or small
head ofthe epididymis, hangs over the testicle, and points back-
wards to the perineum, and  can  be  felt through  the whole
coats; and that the body ofthe testicle A, is towards us when
we examine a patient.—Further, as the letters in figure 1. and
2. refer to the same points, we have only to notice the fainter
indication ofthe 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 ofthe 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  represent-
ed, 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 vesiculae seminales.

  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 a cellular struc-
ture : each of these bodies is about three fingers-breadth in
length ;  their backmost point  is large and round, and, at tbe
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 ofthe  base of the prostate gland.
  As we have seen, the  peritoneum does not  descend,far
enough betwixt the bladder and rectum to cover or invest
these vesiculae; 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-
 icuke 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 liumoralis.  From this point we can trace all the connec-
tions of the other parts.
   Vol. hi.                 Q q 
30G
OF  THE TESTES.
the canal.   Their outer surface is covered with a fine mem-
brane, which connects these cellular convolutions.
  The vesicular are copiously supplied with arteries : their sur-
face is covered with veins and lymphatics.  Heister, Winslow,
and others, have described small  glands seated in their sinuo-
sities ; hut these are confidently denied by others.  These ve-
sicular are themselves glands, or in other words, the  arteries
secrete  into them a peculiar fluid.   The  forepart of each of
the vesiculae, 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 vesiculae is very
particular:  the duct and the extremity of the vesicular tube
■join, aud they together open into the urethra.   There is no-
thing in tbe human structure to discountenance the idea that
the semen may pass retrogade from the vas deferens  into the
vesicuUe seminales, but as in some brutes the vas deferens has
no connection with the vesicuUe seminales, it is to  be  pre-
sumed  that they  are not mere  receptacles of the secretion of
the testicles.*
   The  extremity ofthe vas deferens joins the duct ofthe ve-
siculae where it is imbedded in the prostate gland ; the union of
the vas deferens and duct of the vesiculae is not attended with
an enlargement ofthe 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 vesiculae appear to be useful in adding a fluid to the se-
cretion of the testicle, which being poured together into the
simta of the urethra,  are then  sufficient to distend this part of
the canal, by which too the ejaculator muscle  is exerted  and
 cliect 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 vesicular 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.
3W
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 ofthe 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 ofthe seminal vessels
open; and around it there are innumerable lesser foramina and
mucous folicules, the duct ofthe prostate gland.
  The sivus pocularis is the  sac or large lacuna formed
within the caput galinaginis; its mouth is directerj farwards,
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 ihc
ducts are found opening  on the sides of the sjnus. 
TIU.
ANATOMY
OF THE
     ]•EM ALE  PARTS OF GENERATION.




    THE ANATOMY OF THE PARTS IN THE FEMALE PELVIS.


 x HE parts of generation are divided into the external, which
are those without the pelvis; and the internal, or viscera ofthe
pelvis, and which lie within the bony circle of the pelvis.
CHAP. I.
          THE EXTERNAL PARTS OF GENERATION.


 A HE external parts of generation are the mons veneris, la-
bia?, clitoris, nymphas, urethra, hymen, and carunculae myrtir
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 developement
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 women
it is of an enormous size; and in some warm climates a parti-
cular  laxity prevails.  From the hair on  this part, marking the
age of puberty, it is  called pubes.   As the lax texture admits
of distention with the fluid of anarsarca, it is sometimes from
this cause very greatly swelled.
  The labii.—These  are often named  alae, from a  slight re-
semblance to wings, and they are also called externa?, magna?,
or majores, from their place, and from their superiority in res-
pect of size  over the nymphae.  The labii seem to be the mons
veneris continued downward  and laterally, until meeting be-
low, they form the vulva; at their lower angle by their union
they form the fourchette, or frenum  labiorum.   The structure
of the labiae is similar to that ofthe  mons veneris ; sometimes
one is larger than the other.
  The great sensibility of the membrane  which lines the  in-
side ofthe labii requires some defence, and therefore the whole
surface  is amply supplied with mucous folicules and glands.
The labii are a protection to the other soft parts, so necessary,
that the clitoris, or nymphae, when they project beyond them,   •
are subject to violent inflammation.
  The parts  here  have either such folds,  or are of  so lax a
a texture, as to permit a great degree of distention during the
passage of the child.  But as the labii have no muscular pow-
er, 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 unori-
ginal size.  In man, hernia descends from  the abdominal ring 
    SiO   THE EXTERNAL FARTS  OF  GENERATION.

    into the scrotum ; but, in woman, when there is a rupture from
    Ihe ring (which is rare) it falls into the labium.
      The nymph.t.  are named labii vel  alae minores, or labile in-
    terns, to distinguish them from the great labii.  They are like
    a miniature representation of the great labiae; 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
    ofthe membrane.  Their size varies  much.  They commonly
    stretch downward and backward, to tbe middle of the orifice
    of the vagina; sometimes no further  than to that of the orifi-
    cium 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 proba-
    ble  that they facilitate the necessary dilatation.
      The nymphae  arc, 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 hasmorrhagy  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 bo-
    fly 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 pre-
    putium.  In short, it has the same sensibilities, the same pow-
    er of erection with the membrum virile; only it has no urethra
    nor spongy body, like that ofthe  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
    hr a peculiar predilection for them.   It is not wonderful that
* Both Riolm and Morgagni have seen the parts without the, nymphs. 
        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.
                     OF THE URETHRA.

  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 slight 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 ofthe
operation, I have experienced great embarrassment, from  an
irregular ulcerated or cancerous surface ofthe 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 ofthe 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 cir-
cumstances 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.  Thesejire tumours of the ova-
rium, tumours of the womb, polypi, distention of the vagina.. 
•312    THE  EXTERNAL  PARTS OF  GENERATION.

displacement ofthe womb, as procidentia, prolapsus, retrover-
sio, he.; and lastly, the child's head in labour.
  The ovarium being enlarged, and falling down into the pel-
vis, either presses upon the neck of the bladder, causing ob-
structions, or pressing and weighing on the  fundus of the blad-
der, it occasions a stillicidium urinae.
  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 ofthe 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 ob-
stinate 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 mtdwife, 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 ofthe womb. 
THE EXTERNAL PARTS OF GENERATION.     313
First Plan ofthe 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 tbe symphysis of the os
pubis.—E, the fundus ofthe womb.—F, the os tincae, or orifice
of the womb.—G, the vagina.—H, the rectum.
  Prolapsus,  or falling  down  of the  womb, is frequent with
those who 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 ofthe pelvis.
  We rnay observe also from the place of the vagina G, that
its diseases, its scirrhous hardening, its distention by the men-
ses, will also compress the urethra and neck ofthe 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 tb,e connection
  vol. m.                 R r 
314    THE EXTERNAL  FARTS 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 ofthe parts.
Second Plan ofthe Female Pelvis.
   A, the os pubis; B, the  sacrum ; C, the bladder of  unne
much  distended, and rising above the pubes ; D, the con-
nection betwixt the back part ofthe bladder, and the upper
part of the vagina, and  through which the rising of this part
ofthe  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, wiiich is stretched in consequence ofthe 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

iiack 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
alterwards 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 vagina:.—This is also named ouificium exter-
num, 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 ofthe 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 ofthe 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, for I
know that the perforation for the  evacuation of the menstrual
blood is sometimes necessary.  When I have seen the imper-
forated vagina in 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
membrane 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 easily be  destroyed in the preparation  ofthe
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 caruncul* 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 ofthe parts; and they  accordingly
disappear during the passing of the child's head.
  The fossa navicularis is a sinus, supposed to be of the
shape of a boat, whence its  name.   It  is formed betwixt the

 * 1 need not say bow unnecessary and improper such operations are. All rigidity, callosi*
ties, evc.i tumours, and undoubtedly the hymen, will yield to that general relaxation of nf»
'ft* nails, which takes place upon the commencement of labour. 
        THE  EXTERNAL  PARTS OF  GENERATION.    317

proper  orifice of the vagina and the fourcbette, 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 PELVli.


 X HESE parts are the bladder of urine,  the  vagina, the
womb,  the oVaria.  We shall consider thein 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
ofthe 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
Lhe 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 ofthe bladder into the vagina.
  A woman had for a very long  period suffered great distress,
not only the ardor urina?, 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 ofthe 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 ofthe womb, with the back part
ofthe 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 ofthe vagina
being at  the same  time reflected into the  lower part, pulls
down  the bladder with it, and when (the disease increasing)
the womb covered by the vagina comes to hang from the ex-
ternal 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.
■Action shewing the effect of Procidentia on the Bladder.
  Tliu , 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,
*nd carrying the vagina before it; E, the  vagina still covering
ihe womb,  hut the pfifice of the  womb appearing,  which i- 
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 tbe 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 to
the orifice of the womb.   Its orifice is bounded below by the
fourcbette ; 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
ofthe vagina is of a conical form.   At the outer orifice it i?
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 ofthe surrounding fibres, are in contact.
  In the natural state,  the orifices ofthe 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 ofthe
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 fol-
lows the axis of the pelvis ; and as the interior of the two cir-
cles cut off by the same radii is the shorter, the vagina is longer
behind than before.  • 
32ft              OF  THE  VAGINA,  &t*
   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 tincae, 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 ofthe 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 retaarkable 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, &C.
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 ofthe 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 tbe 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 ofthe 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 tbe 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 violently
 distending, and compressing the  parts, while the woman,  ex-
 hausted by the previous stage, is unable to complete the deli-
 very.   From violent inflammation, with a deficiency of secre-
 tion, there arises a cold  and flabby state of the parts.  When
 the woman is delivered, the parts  have suffered so much, tlat
 they slough off; sometimes the  urethra is laid  open on  tb«
 forepart, and sometimes the rectum behind.
   vol. in.                 S s 
222
      OF THE WOMB.


      SECTION III.

       OF THE WOMB.

Fifth Plan of the Female Parts.
                       Uterus and Tubes.
   This little drawing will better explain the figure ofthe womb,
 when dissected from the vagina and surrounding membranes,
 than the usual reference to a bottle, a peatftl^^-owder-flask.
 As, indeed, it resembles no familiar oibjftt thai 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 tbe Fallopian tube^  The body ofthe
 uterus, which is that larger  part betwixt the fundus  and the
 narrowing below; the ctRVix, which is the  narrow neck;
 and the os tincje, or orifice formed 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 ges-
 tation it keejfc 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 ofthe pelvis, or a very little below it.  In
 the foetus, the womb  is like the bladder, considerably above
 the brim ofthe 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
 distinct 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.*.*
 Their canal is very small towards the uterus, but enlarges ; and
 is patulous  towards  the  extremities.   These canals are  tbe
 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 ofthe  uterus is formed ofthe  perito-
 neum ; for this membrane passing down before  the rectum,
 and ascending again, and covering the neck, body and fundus
 ofthe 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 for its becoming an
 abdominal viscus, for in pregnancy it rises out ofthe pelvis; and
 being distended before the bowels,  assumes in every respect
 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 ofthe peritoneum being a thin expansion of it, has some-
 times had the name of alje vispeutilionis : 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 j
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
celln'ar membrane of the top of the thigh.  In  the gravid
uterus, both the broad  and tbe  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 tbe 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 ofthe uterus,  are the tendons of
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 ofthe uterus to the axis ofthe  pelvis.

              OF  THE  CAVITY OF THE UTERUS.
Sixth Plan.
  The 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 cavi-
ty.   A; the cavity ofthe 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 off 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 lar-
ger.  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.
   Thi- peculiar shape of the cavity of the womb, and the
hardness and small degree of vascularity of the  lower part, is
ofthe most essential importance.  The upper part, the pro-
per cavity of the womb,  is prepared for  the  reception and im-
mediate adhesion ofthe ovum, when it shall have descended
through  the  Fallopian  tuoe; but  the  long callous cervix is
providid, 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 gluing
 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 va-
 gina, and not from the womb,  because it flowed sometimes
 during gestation.   This is a fact whioh cannot  be denied.  I
 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                 OF  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 shewn not only
the mark of blood poured out from the inner surface, but that
the whole substance ofthe 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 ofthe womb, when
the inner surface has been turned out after labour, and has re-
mained thus inverted, and protruding from 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 tbe 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 ulerus; it is  distributed to
 the Fallopian tube, the ovarium, but chiefly to the body  and
 fundus of the  uterus, where it forms remarkable  anastomoses
 with the artery ofthe other side.
   The lower artery—the uterine  artery, comes in
 general from tbe hypogastric artery, takes  also a serpentine
 course, and is distributed to  the vagina, and tbe lower part of
 the uterus, and inosculates largely  with the other vessels, both
 in the uterus, and  by particular blanches on the side of the
 uterus.
   In the first place, it appears, that this copious supply of ves-
 sels to  the uterus,  from four diffeunt sources, is a provision
 that tbe womb and secundines shall not by any accident of po-
 sition, or by the progress of  laboui and the consequent com-
 pression of one or both the lower vessels, be deprived of their
 due supply of blood.  Again, theii  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.
 t This might have been an early  abortion, or perhaps the decidua, which it is said i?
•omelimes formed at the menstrual period. 
OP  TBE  WOMB.
327
liar and local action duriog menstruation, and that the blood
will move more languidly when the stimulus of the womb has
ceased.  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 a part must be supplied by a more
tortuous form, as well  as an enlargement ofthe calibre  of tbe
vessels m a particular manner illustrated by the  change which
takes place in  these vesstls 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, asDaventer: 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 uninipregnated state.  Thus, when it has
been cut in  the living body, upon the approach of labour, as
in the  Csesarean 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 foetus
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 conceving,
and desire  is extinguished ;  they, therefore, bestow what  is 
328                 OF THE  WOMB.
essential to generation upon the part ofthe 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  spec 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 oi 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-
luiion in their system, and instinctive desires, would but ill ac-
cord with that superiority in attributes ofthe 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,  which preserves the womb in a state
of preparation  for the reception ofthe ovum,  and the ovaria
in a state of preparation for impregnation.  Thi* is  the effect
of menstruation. 
OF  THE WOMBc
3£9
                       OF PUBERTY.

   Authors have long, with many expressions of surprize, 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.
" 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  tbe 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 ofthe 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 anew torrent of blood, augments the  force so

   * 1 have shown that the tortuous arteries always form a provision for the occasional in-
 crease of the action and acceleration of the blood.

   voi..  in.                  T t 
JJO
Ob  1HK WOMB.
far 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 ^erum, and by suffering  a greater dis-
tention, they  at last emit the  red blood itself.  The same
greater ina"pulBe. 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
iimbs ; neither can  we  believe that congestion  and plenitude
are produced in the femalstsystem,  from the deficiency of per-
spiration, from their more lax and weaker solids compared with,
man, from their  indolent and sedendary 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
ofthe  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 ofthe 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  foetus lose their preponderance : we see  others, which
served some purpose in the foetal 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 continual enlargement, suddenly  rising  at  certain stated
periods from  their embryo state, and enlarging and pushing
up  through the gums,  when it becomes fit that tlie  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 ia 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 controul 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
foetus ; 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 tbe  end  which nature  is accomplishing.  To  explain
this, I may be allowed to take a short preliminary 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 ofthe uterine system, after
the object  is accomplished.  It is not the discharge of a few
ounce? of blood  which relieves the system ; for drawing blood 
332
OF  THE WOMB.
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, when 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  haemorrhagy from remote parts of
the body, some, whose opinion I greatly value, do not consi-
der  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 the 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 ofthe 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 ofthe 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 ma-
tured and brought to pululate,  and almost to start from their
investing membranes.  Without the ovaria are in this state of
preparation,  conception cannot take  place.  In considering
this subject of menstruation, the mere circumstance ofthe 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 hcemorrhagy, from  what kind of vessels the
blood flows.   From the circumstance of the hemorrhoidal
discharge, which certainly is from veins, and from the lochia,
which is generally supposed to be a  discharge from the venous 
OF  THE WOMB.
333
 sinuses of the  womb after delivery, we have the argument of
 analogy, that in menstruation  also it is a venous discbarge.
 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 hae-
 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 tlie other hand, we observe that
%it is the necessary consequence of an increase ofthe  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
 distinguish  their  mouths;  or that of Meibomius,  who said
 he introduced  bristles into them.   That  anatomists have
 introduced  bristles into pores,  or foramina, it would be  ungra-
 cious to  doubt, but that these  were the orifices of exhaling ar-
 teries, is difficult to believe.   I rather imagine, that there is  a
 provision 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 ofthe 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 ofthe vessels ofthe 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 hajmorrbagy, there is a change in the properties of the
   effused  blood.                       .  .   .             ,
     When there is an unusual source  of irritation in tbe womD,
   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
OF  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 some 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 lo 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
find 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 ofthe 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
ofthe fruit is probably a provision ofthe same kind, or when 
OF  THE WOMB.
335
 it has fallen, to lay the foundation, by its decay, of a soil suit-
 ed 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 tbe 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 ofthe
 seed, vessels or tubes,  inactive, but ready  on the  supply of
 heat and moisture, to  absorb the nutritious  matter ofthe albu-
 men, 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 atmos-
 phere.
   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 nu-
 tritious matter of the  albuments to the  embryo  plant.  In the
 first stage of this change,  the matter absorbed by the vessels
 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 tbe 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 for
  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 ben.  The ovarium is placed on the  back-bone, innume-
  rable yolks are seen  gradually formed, and successively in-
  creaeing 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 ofthe 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  tbe e^g-b^d, tbe 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  vivapa-
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 «'gg, 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 fully 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 tbe  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-lhat they take a pretty firm hold on its tenacious sub-
stance.  These chalaza are not fixed to tbe  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 cicat-
ricula 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,  ougbl 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 incuba-
ted 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.—They 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
ofthe 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 mere-
ly 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 extremeties of these vessels, or is there first an  action
of the heart of the chick ?—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 to 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 ofthe 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
   VOL. Iljj                 U u 
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 tbe active
exertion of the living powers, beginning by 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
ofthe 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 there are other circumstances wor-
thy of notice : as the chick grows  by tbe  absorption of 'he
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
ofthe 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 un- 
OF  THE WOMB.                33$
 lil its strength is equal to the digestion of its appropriate food.
 And in thb 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 ofthe 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  presenc  ofthe
 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 tbe 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                OF 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 we 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 ovnm is impregnated  while in the ovarium, and not upon
its descent into  the  womb, which  is  proved from the  foetus
sometimes remaining in tbe 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 seminalis 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  ofthe mere sympathy  ofthe 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 their
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 IN
           THE EARLY  MONTHS  OF PREGNANCY.

  The ovum, when it has descended into  the uterus, and is
perfecl in its structure, is a soft oval mass,  fringed with  ves-
sels, and composed of membranes containing the early foetus. 
OF  THE WOMB.
3*11
When opened* or dissected,  it presents three cavities, or we
observe the^tus to be surrounded with  three distinct menp-
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, tbe 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 which it receives in the womb.*
Plan of the Membranes.
A, The Foetus.  B, The Amnios.  C, The Chorion.   D, The
                      Vesicula Alba.

  Amniok.   The amnion is the vesicle which immediately in-
volves the foetus.   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 foetus
is suspended.  In the abortion ofthe 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 foetus, while it is a  provision also for
the regular presentation of the head of the child, for now the
fcetus 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 AJbin Ann. Acad. lib. i. cap. nviii. and xix. Hunter's  tables of the Gravid
Uterus—Camper icones. 
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
 ofthe foetus; on the inside  it is smooth, and betwixt it and tbe
 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 ofthe womb during la-
 bour, the chorion has relatively become very thin and weak.
 On  the  outside the chorion is shaggy and vascular, and con-
 stitutes those minute extremities ofthe vascular  system ofthe
 ovum, which attach to the  surface of the womb, or rather to
 the flocculent membrane which it throws out.
  The umbilical cord. When 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 ofthe 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 foetal 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 little
 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 disap-
 pears.   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

after the perfect establishment of the connection betwixt the
foetal 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 uterine system, 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
OF  THE  WO*HB.
uterus in  out-line ; B, the amnion  with the fostus ; C, the
chorion.   Now it is observed, upon  a careful examination  of
an abortion  ofthe early months, that besides the chorion and
amnion, there is a spongy membrane of two distinct laminae
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 perforatsd
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 thrown 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.
  Dr. Hunter supposed, that the ovum passed into the cavity
ofthe uterus whilst the coagulable lymph was pouring out by
the arteries ofthe 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 detidVious membrane B, hy 
OF  THE WOMB.
346
• 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,  op 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  Reflexa,  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
                         FffiTUS.

  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 ofthe 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
  vol. in.                  X x 
346                OF THE WOMB.
a plant grow and spread towards the light..  The  piacenta  i
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 four inches upon tbe 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 tbe 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 for
insuring  attachment there.  But when  it does form low in the
womb, or on  the orifice itself, we then perceive the reason of
nature's  solicitous care  in preventing it;  for  it occasions tbe
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 foetus
(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 ofthe
placenta is thrown off with the other secundines, and does  not
separate from the foetal part  of it.   While, in other  vivapa-
rous animals, the monkey excepted,  the filamentous extremi-
 ties of  the foetal vessels separate  from the  glandular  mass
 formed by the  maternal vessels of the uterus.
   The placentary vessels of the foetus never touch the surface
 of tbe  womb,  but communicate with the  maternal system
 through the vessels of the womb, which pierce the deciduous
 membrane.  Still the question ofthe precise  manner in which
 the  vessels of the foetus communicate with those ofthe mother
 remains undetermined.   1 conceive that in the early stage  the
 deciduous membrane  being thrown  out by the action of  the
 uterine vessels, those ofthe chorion stretch into it, and absorb 
OF  THE WOMB.
347
ihe nourishment.   The decidua is a vascular Wmbrane, 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 ofthe placenta, we find
it 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  recognize it as
the decidua.  This union, however, betwixt  the maternal and
foetal parts ofthe placenta is intimate, and it is impossible to
determine by dissection with the knife, whether there be in-
osculations betwixt the maternal and foetal 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  FCETUS.

  Some physiologists, observing the strict analogy which exists
between the function ofthe placenta and tbe 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 in-
to 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 ofthe ovum,  must be the
production of  the foetal system.  Further, when the ovum has
• I speak after dissecting the ovum of the third month. 
348
OF  THE WOMB.
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
fostus.   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 ofthe 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 ofthe mother and
child there are many opinions.  The simplest explanation, but
the furtherest from truth is, that tbe 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 are
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.
   A little 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 natu-
 ral to suppose, that the circulating fluids ofthe adult are calcu-
 lated 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 foetus, 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 tlie  trachea, Tie eupposes that the feetiw
 respires, and receives ojtveenation from the liquor smni; 
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 ofthe brain pour out their blood, the woman
does not suffer, nor is  there any danger of hasmorrhagy from
the cord after the delivery ofthe child.  Again, what does the
analogy of other animals  show us ? We may observe,  in thft
first place,  that probably on account of the peculiar form of
the womb of woman, and in  these circumstances to  guard hei
from danger of hi morrhagy during delivery,  it  is necessary
that the placenta should be accumulated towards the fundus
ofthe 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 ofthe pla-
centa remaining with the womb, as in other animals, the whole
mass  separates  on  the delivery of the  child.   The necessity
for this  firmer attachment of the human placenta, causes the
connection betwixt tbe foetal and the maternal portions 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 foetal 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 foetal 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 umbi-
lical vessels take up by absorption the nutritious matter neces-
sary for the system  of the  child, and that this is secreted by the
vessels ofthe  womb.
   Investigation  in  every  department of natural history shows
..* similarity and a simplicity in the operations of nature.  Com-
parative anatomy may be  brought with much advantage in il-
lustration of the very  obscure laws  which 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 
 35U                 OF THE WOMJB.

 artery which phases out of the umbilical co*d ofthe chick, and
 which is distributed to the membranes of una 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 fatus 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
 in every essential particular to its own increase,  wherefore
 should we suppose that the foetus 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
 ofthe 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 ofthe womb, as  it
 is required by the appetency of the foetal system.  As in the
 egg, the membranes surrounding  the white have the same ef-
 fect upon the blood, which is afterwards produced by the lungs ;
 so has the placenta of viviparous animals the double function of
 supplying nourishment, and the purifying of their blood.   The
 umbilical vein carries back pure arterial blood, and the com-
 mon opinion is, that the blood of the foetus 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 foetal blood
 is imbibed by the maternal blood; and  in this way the blood
ofthe foetus  is purified.  It is not  necessary to  this change on
the foetal blood, that it should come in immediate contact with
Hie  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 foetus 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 re-
ceived into the Fallopian tubes, but either from  a want of suf-
ficient  dilatation and action in  them, they have not been able
to propel it  forward, or  the  ovum, taking upon it that action
which is destined to form its connections with the uterus, ad-
heres, 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 tbe cavity of the abdomen amongst
tbe 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 ofthe
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 ofthe 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 ofthe ovum and foetus.
   It shows  us  how far the action previous and  consequent to
impregnation is a universal and sympathetic excitement ofthe
uterine system; that the decidua is formed  in  the cavity of
the womb, although the ovum does not descend.  This points 
352
OF  THE WOMB.
out to us how careful nature is, that there shall be a reciprocal
action in the ovum and womb, so as to insurer 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 for
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 muscularity 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 ofthe 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 \e
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 THE 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 ofthe 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 
OF  THE WOMB.                -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 af-
terwards 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 ofthe pelvis.  Having de-
scended considerably, the os tincae 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 tincae re-
moved from the point of the finger.
  Now the ligaments of the womb  direct it forward,  and  it
rises 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 ofthe 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 ofthe 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
ofthe  womb.
  The muscularity of  the uterus is increasing 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 tbe 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 ofthe
womb is altered, it loses its viscidity, and all the parts  are re-
  vol. in.                V y 
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 ofthe child, yield and  relax previous to labour.  The
action of the womb is at  first feeble,  as  might be expected,
and  accouchers  have  marked these stages of a natural la-
bour.
  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 water 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 ofthe mother against compression by the head ; yet
nature intends this stage to  be short, for it is the period of dan-
ger.   I here is now  obstruction of urine and faeces, and the
vessels of 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.   Ihe face ofthe woman, per-
haps, before pale  and flat,  becomes red and turgid, tbe 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 ofthe 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 the
head forward under the pubes ;  at  last, after several pains, it
riaes with  a half turn, and is delivered.
  4th. The fourth stage, is the delivery ofthe 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 tbe 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  of
the compresssion ofthe 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 descended into the brim; as tbe
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 lustily.   At first the  breath- 
356
OF  THE  WOMB.
ingonly renders the pulsation ofthe cord feeble, but presently
the puliation 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 ofthe 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 hae-
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 MAMMA).

  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 becreted, 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 ofthe 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 tbe 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 mammae, 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 ofthe 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 ofthe
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  stimilus  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 ofthe 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 mammae,
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.
,xiie end. 
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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. Tho-
mas having had opportunities  of actually observing the  diseases and practice of different
countries, but especially those of hot climates,  and  being conversant  with tbe writings of
our best modem authors and teachers, may be considered as well qualified  to undertake  so
important a task.   We think  that Dr. Thomas has acquitted himself of his undertaKing  in
a manner highly creditable to  him as a man of research,  and as a Practical Physician, and
that his Work  deserves to stand high in the catalogue of this kind of compilation."—Lon-
don Medical Review.
  " In compilation* of this sort,  it is sufficient  that, in addition  to a clear  and  methodical
arrangement, due diligence be employed in collecting from the proper sources, and judgnmnt
in discriminating 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 the  different subjects are treated, with brevity
and perspicuity.  The  Author has chiefly followed Dr. Cullen, both in the classification  of
diseases, and in his text; but it is necessary to add, that Dr. Thomas does not  prove a ser-
vile copyist.  He has abridged with  judgment, has added modern opinions and discoveries,
has frequently introduced the result of lus own experience,  and  his  performance thus be-
comes an useful Compendium of the present State of Medical Practice."—Monthly Review.
  " We have read this Work with great satisfaction,  and think it a concise but judicious
abstract of the Practice of Medicine.  The Author's description of diseases  is clear and
characteristic:  his remedies appropriate and well chosen.  His description of  the Yellow
Fever is peculiarly accurate."—Critical Revien.
  " Books of this kind,  wheu properly executed, containing the opinions  of the best wri-
ters on the several diseases, abridged and placed together before  the reader, may sen'e for
occasional reference to refresh  the memory, and save the  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 elabo-
rate 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 pecu-
liarly well qualified to decide on the merits of a work  on Medicine.
  " The preceding work is executed  with a degree of ability and judgment which  reflects
much honour on the talents of the author.  In Great Britain,  it stands so high in public
estimation as to have passed through several editions within a short  period; and is consi-
dered 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'*
work, leads us  readily to coincide with tlie opinion expressed  by Dr.  Miller, that "it is ex-
ecuted with a degree of ability and judgment which reflects  much honour on the talents of
the author."—American Medical and Philosophical Register, Vol. 2.
  Dr. Thomas, in this work,  has condensed more facts and more precepts for the manage
ment of diseases than any modern medical writer we have met with —Nnc-York Medir.i'
Repository, Vol 3, third series. 
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