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SPECIAL,

ANATOMY

▲ND

HISTOLOGY.

BY J.

WILLIAM E. HORNER, M. D.

PROrESSOR 07 ANATOM? IN THE UNIVERSITY OF PENN3YLVAKIA— MEMBER 07 THE IMPERIAL

MBDico cqiroroical iriT]-i[|T nr wi HFTrnnnnnn nr thb

AMERlC^,>rf»iL6S9PHICAL socieTtT^

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Mullum adliuc re%^t oneris, niultumque restabit, nee ulli nat^jHJsjrmille saecalJ prjecluditur occa^Q ml^id adjiciendi. ^ ' *

I]¥ TWO VOIiUHES.

VOL.. II.

SIXTH EDZTZON.

PHILADELPHIA:

LEA & BLANCHARD. 1843.

U

Eastern District of Pennsylvania to wit : —

BE IT REjMEMBERED, that, on the seventeenth day of October, in the fifty- first year of the Independence of the United States of America, A. D. 1826 — William E. Horner, of the said district, hath deposited in this office the title of a book, the right whereof he claims as Author, in the words following, to wit : —

" A Treatise on Special and General Anatomy. By William E. Horner, M. D., Adjunct Professor of Anatomy in the University of Pennsylvania, Member of the American Philosophical Society — Surgeon at the Philadelphia Alms House, &c. 'Multum adiiuc restat operis, raultumque restabit, nee uUi nato, post mille ssecula praBcluditur occasio aliquid adjiciendi.' Seneca, Epist. In two volumes. Vol.1.

In conformity to the Act of the Congress of the United States, entitled, " An Act for tlie Encouragement of Learning, by securing the Copies of Maps, Charts, and Books, tAhe^SlSthors and Proprietors of such Copies, during the times therein mentioned" -•^—And also to the Act, entitled, " An Act supplementary to an Act, entitled, "An Act for the Encouragement of Learning, by securing the Copies of Maps, Charts, and Books, to the Authors and Proprietors of such Copies, during the times therein mentioned,' and extending the benefits thereof to the arts of designing, engraving, syid etching Historical and other Prints."

D. CALDWELL, Clerk of the Eastern District of Pennsylvania.

GRIGGS & CO., PRINTERS.

TREATISE ON ANATOMY.

BOOK IV.

PART ir.

61ANDS-AND THE ORGLNS OF ASSIMILATION.

CHAPTER I.

Prolegomena on the Structure of Glands.

The intimate structure of glands was but imperfectly attended to previously to the celebrated Malpighi, who, in the year 1665, pre- sented to the world his work entitled Exercitationes de Structura Viscerum. Till his time the most minute inquiry had gone but little beyond the point of observation, that glands consisted, as an ultimate arrangement of their particles, in small granular bodies called Acini, from their being clustered like grapes or berries, growing very closely together around a common stem and its branches.

The simple idea, propounded by Malpighi, is, that each acinus being a gland of itself, consists of minute spheroidal sacs, which re- ceive the secretion from the blood vessels. Darwin at a much later period modified this idea by advancing that the change occurred in the spheroidal sacs themselves. The celebrated Ruysch having im- proved much the art of injection, was enabled to show in his pre- parations, that what Malpighi considered as sacs or follicles, were really formed of convoluted blood vessels. He hence adopted the opinion, false in itself, that the substance proper of glands. i«?

Vol. II.— 2

6 ORGANS OF DIGESTION.

formed wholly of blood vessels, and that the minute branches of the latter terminate by direct inosculation with the ducts of the glands. As another step in this inquiry, Mascagni andCruikshank showed that the secreting canals in the mammary glands com- mence in the form of cells — and Professor Weber has discovered the same feature to exist in the structure of the salivary glands of birds and mammalia, and of the pancreas of birds.

The existing state of opinions on this interesting subject, is de- rived from J. Muller, Professor of Anatomy, Berlin, who* has announced as the result of his inquiries on the structure of the se- creting canals in all kinds of secreting glands, that such canals are found every where to form an independent system of tubes. *' That whether they be convoluted, as in the kidney and testis, or ramified in an arborescent form, as in the liver and salivary glands — whether they terminate by twig-like ccEca, as in the liver — or in grape-like clusters of cells, as in the salivary glands, pancreas and mammary gland — their only connexion with the blood vessels in all cases, consists in the latter ramifying and forming a capilla- ry net-work on their walls and in their interstices: and that the finest secreting tubes, namely, those of the liver and kidneys, are always several times larger in diameter than the minute ramifica- tions of the arteries and the veins."

This doctrine is, therefore, a modified resumption of the more ancient one of Malpighi, and claims merely for the entire surface of secreting tubes what Malpighi thought to belong exclusively to their incipient extremities. The leading argument in its favour being, that in every case there is a minute vascular net-work of capillaries discernible on the parietes of these canals, and whose capillaries are much smaller than the secreting tubes themselves.+

Glands of the most simple shape are mere recesses or pouches in the thickness of the membrane or surface to which they belong. (Folliculi.) In some instances they are very superficial and their bottom is reached through a wide orifice — in other instances their mouths are somewhat contracted like the neck of a bottle — in other cases they have a long and tortuous course (Tubuli) as the tubuli seminiferi of the testicle. In most of these modifications of a tubular arrangement, from the shortest to the most elongated,

* De Gland. Struct. Penit. Leips. 1830, and Physiol, p. 485. London, 1840. t See capillaries.

GLANDS. 7

the walls of the tube are not absolutely uniform, but it will be found that there are either partial or cellular dilatations of it ; or coecal-like appendages, in great numbers discharging into it, and placed in varied angular relations to the principal sinus or se- creting tube. The stem of a thickly clustering bunch of grapes, the berries being removed, will represent sufficiently well the mere mechanism of this arrangement.

A form of secreting canal a little more complex is where a large sphenoidal dilated sinus exists with tubules radiating from it (Folliculi aggregati) in lines more or less regular, the sinus itself having a large patulous orifice connecting it with the surface upon which it discharges. One of the follicles of the tonsil glands may represent this arrangement. Also the glandulas linguales on the root of the tongue, which seem to be a mere extension of the lower end of the tonsil gland in the form of an expanded flank, and are not unfrequenlly, directly continuous with the tonsil gland. Another form of this composite canalicular arrange- ment is when the collection of tubules are more in a line, the branches diverging more slightly from each other (Folliculi com- positi) and each of those branches again diverging into other branches, and so on successively to their last twigs. The mei- bomian glands and the vesicula) seminales are instances of the linear composite follicle or tube having but one set of branches. A lactiferous duct is an example of the composite secreting canal, or tube with a numerous and indefinite succession of finer and finer branches, and, which end finally in club-like dilatations. Some of these secreting canals end in a divarication of branches resembling the flowering ends of the umbelliferous plants.

Some of the glands present a species of regularity in the order of division of their secretory canals. The principal trunk of the latter gives oflf at intervals nearly uniform lateral branches, these branches give oflf with regularity other branches, and the latter again observe the same disposition. This modification is preserved to a remarkable degree in the pancreas, and is also visible in the salivary glands, the lachrymal, and the mammary. In cases of this kind the lobulated condition is very clear, the lobules being rather feebly held in connexion with the contiguous ones by loose cellular substance, allowing the lobules to be easily separated from each other by drawing at them. The lobules themselves are ulti- mately divisible into granules, (glomeruli or acini) which under

H ORGANS OF DIGESTION.

the application of the microscope are found to be cells aggregated, surrounded by a fine vascular net-work of capillaries, and making the peripheral end of the most minute secreting canals. The trachea with its division into bronchia, bronchioles, final air tubules, and air vesicles at the end of the latter, represents on a large scale the division which is seen in glands on a small one. An unsettled question is, whether these vesicular terminations are in all cases kept distinct, or whether from a defect in their parietes they do not communicate like the air vesicles of the lungs, and have in that way a tubule common to several. In some instances the ulti- mate secretory tubules of those ramified ducts are arranged like cosca around the branches of the latter.

' Another form of the ramified secreting tube is where there exists lio division of the gland into lobules, but it is resolved at once into acini. These acini being formed upon the final divisions of the secretory tube, which rise up in fasciculi, giving a brush like or penicillous appearance. The liver is an example of the above, it being doubtful whether there is any spheroidal enlarge- ment at the free end of the penicilli.*

The glands with successively ramified secreting tubes are the

Lachrymal gland.

Mammary gland,

Salivary glands as Parotid, Sublingual, and Submaxillary,

Pancreas,

Liver.

The glands of an almost pure tubular structure and indisposed to ramify, except in a very limited manner, are the

Kidneys, Testicles.

The Meibomian glands and the Vesiculas seminales may be con- sidered as a tendency to the same structure, but in a more abbre- viated and simple condition, by some they are considered merely as branched follicles.

The summary of the secretory glandular system then is for it to present itself in the simple short tubular state of shallow depressions,

* From peniculus a painter's pencil.

GLANDS.

9

or crypts of a mucous membrane as in the urethra and bladder; — in bottle-shape cavities; — in closed lenticular cavities, as Peyers's Glands; — as the follicles of the alimentary canal which are either sin- gle or branched; — and as thin follicles with a glandular matter or parenchyma, principally vascular, forming a nidus around tfiem, and which follicles may themselves be either simple or branched in some degree.

The principal object of a secreting glandular structure would seem to be a development or augmentation of surface sufficient to the purpose of elaborating the quantity of the specific fluid called for; in other words, for getting area for the requisite ends, like the display of surface in the interior of the lungs for air enough by respiration. They seem, therefore, as said by some, to be a sort of efflorescence from the surface, or cavity upon which they discharge; being formed of canals with closed extremities as origi- nally asserted by Malpighi.

It is denied by Miiller* that there are acini in any glands what- ever (the testes of some few fishes excepted) existing, as com- monly understood, to wit, as solid granules executing secretion ; by means of their glomeruli of blood vessels having ducts arising from them, in an unexplained way. On the contrary, he asserts, that acini are merely bundles of fine tubes formed by the ends of secreting canals, or frequently by collections of the vesicular termi- nations of the latter. The term acinus in its qualified sense is suf- ficiently proper, but it should be remembered that in receiving it according to its meaning, which is a berry or grape, the skin of the grape and its pedicle are alone to be understood, the pulp being omitted.

In regard to the connexion with the blood vessels, their cavities are as stated not to be considered, according to Miiller, as continuous with the cavities of the secreting tubes, but merely ramified on them by countless capillaries, the arteries simply terminating in the veins as in the case of the lungs, or, I may say, of the iHtestinal canal. Tiris theory is, however, almost too exclusive; there are most pro- bably, organized porosities in the capillary system, I am disposed to think, in the venous especially, forming a communication be- tween the vessels and the canals on which they ramify; it is rather too easy to pass a minute injection from the capillary system into

» Physiol, p. 501.

2*

10 ORGANS OF DIGESTION.

the canal upon which it ramifies, for us to suppose that every such case is one of rupture. We must, also, upon the ground of per- sonal observation to the contrary, decline the opinion of Professor Miiller, that there is no communication betv^reen the secretory ducts and the lymphatics.

The cause of the massive character of many glands and of their shape may now be understood. The shape of glands must depend measurably upon the space and circumstances in which they are accommodated, the diversity of shape in the three salivary glands shows that this is a point of merely local convenience, and is subordinate. Their size, however, is upon another ground : this is regulated by the amount of secretion to be done, and by the necessity of this secretion being collected at one or more points. The process of assimilation requires the bile in the duodenum only, and that in large quantity ; hence the liver is both a very large organ and all its secretion is concentrated in one focus. If the necessity for the latter had not existed, the liver like the muci- parous glands might have been disposed in small granules all along the alimentary canal. This hypothesis, by the way, will show how the liver or any other gland may exist in the form of insulated acini without the function being altered; and also show the reverse, how if all the muciparous glands were collected into o'ne mass for the purpose of having a focal point of discharge, that this arrange- ment would require also a single large duct made by the succes- sive junction of branches, just as in the liver.

As the vascular capillaries ramify upon the parietes of the secre- tory tubes, so, their parent branches are found in company with the larger branches of the latter. The development of the two systems is found to be simultaneous. The tubes are first of all planes, then simple canals or cceca, then primary branched canals or cceca, then undergoing an indefinite series of divisions. At first these canals are loose and unconnected, but as the evolution of the gland ad- vances they cohere and become consolidated, but at every period of development and of perfection, the capillaries form a net-work around them smaller than the tubes themselves.

There is no essential correspondence between the construction of a gland and its secretion. Very different glands have similar structure, as the testes and the kidneys, and similar glands have a varied structure in different animals. The liver in one animal is simply in the form of coeca, in another of tufts of cceca; in others

GLANDS. 11

of branches of cells or of a spongy tissue, or as a branched duct having terminal twigs like a feather. The testes are indefinitely varied; the kidneys alone maintain a constant character. The con- struction of a gland is always regulated by the special demand upon it by the condition of the animal in question, hence the salivary glands are exceedingly simple in birds and serpents; the pancreas in fish, and the liver in the lower animals. Where more surface is required, then new processes from the main line of the secreting tube spring up.

Recent microscopic observations have ascertained other new points in glandular structure. Purkinje remarked, that the walls of all secreting cavities or canals are formed by nucleated granules, making, according to his phraseology, the glandular Enckyma. With the aid of Schwann and Henle this enchyma has been found in all the glands and over the entire mucous sur- face, constituting in fact a cellular nucleated epithelium, which is said to execute the specific function of the gland. The diameter of the nuclei is extremely small, being about the o-oii 3 o^ ^ line.*-

There are some other organs called glands, but they diflTer from the preceding in having no excretory ducts. They are supposed to be limited in their function to the modifying in some measure the fluids going through them. One kind of them is formed essen- tially of blood vessels, and they are called ganglia sanguineo-vascu- losa ; of these we have the spleen for the chylopoetic system ; the capsulae renales for the kidneys; the thymus and thyroid gland for the organs of respiration, and the placenta for foetal life. The second kind, called lymphatic glands, (ganglia lymphatico-vascu- losa,) consist essentially of lymphatic vessels entering on one side and departing at the other, after having divided into branches and cells in the thickness of the gland. There are also other glands whose character and functions are still more doubtful, they being found in contiguity with the encephalon, as the Pituitary gland, the Pineal, and the glands of Pacchioni.

The real glands on the contrary not only modify the blood which circulates through them, but give rise to a new fluid as a conse- quence of the transformation of the blood; and this new fluid is discharged for a specific purpose by its eflferent tubes into con- tiguous canals or places.

* Muller, p. 505.

12 ORGANS OF DIGESTION.

CHAPTER II.

Of the Abdomen Generally.

The cavity of the abdomen occupies the space between the infe- rior surface of the diaphragm and the outlet of the pelvis; a con- siderable part of it is, therefore, within the periphery of the lower ribs above, and of the pelvis below. It is completely separated from the cavity of the thorax by the diaphragm, with the excep- tion of the foramina in the latter, for transmitting the aorta, the ascending cava, and the oesophagus. It is bounded, below, by the iliaci interni, the psoas, and the levatores ani muscles; on the front and sides by the five pairs of muscles called abdominal ; and be- hind by the lesser muscle of the diaphragm, the quadrali lumborum, the lumbar vertebrae, and the sacrum. The figure of this cavity is, therefore, too irregular to admit of a very rigid comparison with any of the common objects of life; but a little reflection, on the course of its parietes, will make it perfectly understood. It should be borne in mind, that the very great projection of the lum- bar vertebrae forms for it a partial vertical septum behind; which, in thin subjects, is almost in contact with the linea alba in front, and may be easily distinguished through the parietes of the abdo- men, when the intestines are empty.

The abdominal cavity varies only, inconsiderably, in its vertical diameter, owing to the resistance of the diaphragm above, and of the pelvis below; neither does it change behind, owing to the re- sistance of the spine, the ribs, and the muscles there. But as the introduction of food, the development of gaseous substances during digestion, the evolution of the foetus, and many other conditions, require some provision for its undergoing an easy augmentation of volume; the latter occurs principally forwards and laterally, by the yielding of the muscles and by the extension of their aponeu- roses.

The diaphragm and the abdominal muscles, for the most part, act alternately ; as, the former descends in inspiration the latter relax and give way to the contents of the abdomen ; but in expira-

OF THE ABDOMEN. 13

tion, the abdominal muscles contract, and the diaphragm is pushed upwards by the viscera. In attempts at the expulsion of faeces, and in parturition, these muscles contracting, and the diaphragm being fixed all at the same moment, the cavity of the abdomen is actually much diminished.

The viscera contained in the cavity of the abdomen are of three kinds. One kind is engaged in digestion and assimilation; another in secretion and excretion of urine; and the third in generation. As these viscera are numerous, and it is of great importance to determine with precision their position and relative situation, ana- tomists are agreed to divide the cavity of the abdomen into several arbitrary regions. This is the more advantageous, as the bony prominences bounding the abdomen are not sufficiently numerous and distinct, to afford those obvious points of relation to the vis- cera which are furnished in other sections of the body. To obtain these regions, consider a line or plane as extending across the ab- domen, about two inches below the umbilicus, from the superior part of the crista of one ilium, as it appears through the skin, to the corresponding place of the other side. Strike on each side a line perpendicular to the preceding, by commencing at the lower end of the anterior inferior spinous process of the ilium, and car- rying it up to the diaphragm. Extend a fourth line across the ab- domen parallel with the first, and intersecting the last two where they come upon the cartilages of the false ribs. It is evident that these four lines or planes, two horizontal and two vertical, will. with the assistance of the parietes of the abdomen, furnish nine re- gions: three above; three in the middle, and three below. The central region, above, is the Epigastric; and on its sides are the right and the left Hypochondriac. The central region in the mid- dle, surrounding the navel, is the Umbilical; and on its sides are the right and the left Lumbar. The central region below, is the Hypogastric; and on its sides are the right and the left Iliac. There are also some subordinate divisions : for example, the hollow in the epigastric region, around the ensiform cartilage, is called the pit of the stomach, or Scrobiculus Cordis; and for an inch or two around the symphysis pubis, is the region of the pubes, (Regio Pubis.)

Anatomists differ among themselves about the points of depar- ture and the position of the lines, or rather planes, separating the regions. Some fix them at definite distances from the umbilicus,

14 ORGANS OF DIGESTION.

and others resort to the points of the skeleton. The umbilicus is the most fallacious mark, because its elevation varies considera- bly, according to the state of distention of the abdomen, it being comparatively higher when the abdomen is tumid than when it is not. Neither does it answer to take the anterior ends of the last ribs as the points for the upper horizontal line to pass through ; as they, sometimes, are almost as low down as the umbilicus itself. The superior anterior spinous processes are also objectionable as the points of departure for the vertical lines ; as they leave too much room for the central regions of the abdomen, and too little for the lateral : I have, therefore, after some hesitation, thought proper to substitute the anterior inferior spinous processes; and, especially, as the position of the viscera"; according to almost uni- versal description, is more in accordance with this rule.

General Situation of the Viscera of the Abdomen.

When the abdomen is so opened as to leave its viscera in their natural position, they will be found as follows : —

1. The Liver, the largest gland of the body, is in the right up- per part of the abdomen, immediately below the diaphragm. It occupies nearly the whole of the right hypochondriac region ; the upper half of the epigastric ; and the right superior part of the left hypochondriac. The anterior extremity of the gall-bladder pro- jects beyond its anterior margin.

2. The spleen is situated in the posterior part of the left hypo- chondriac region.

3. The stomach, in a moderate condition of distention, occupies the lower half of the epigastric region, and the right inferior por- tion of the left hypochondriac.

4. The Small Intestine, when moderately distended by flatus, occupies the umbilical region, the hypogastric, portions of the iliac on each side, and also the upper part of the cavity of the pelvis, when the viscera of the latter are empty.

5. The Large Intestine traverses the cavity of the abdomen in

OF THE ABDOMEN. 15

such manner as to perfornn almost the entire circuit of it. It be- gins in the right iUac region by receiving the lower extremity of the small intestine ; it then ascends through the right lumbar and the right hypochondriac, passes into the lower part of the epigas- tric, or into the upper of the umbilical, according to the state of distention of the stomach ; thence it gets into the left hypochon- driac, being fixed higher up there than in the corresponding region of the other side; afterwards it goes down into the left lumbar and into the left iliac ; thence it passes into the pelvis, and, de- scending in front of the sacrum, terminates in the orifice called anus.

6. The Caul, or Omentum, is a membrane, of various densities, in different individuals, and lies in front of the intestines. Some- times it is found spread over the latter like an apron, but on other occasions is drawn up into the umbilical region, forming a ridge across it. It is attached to the stomach and large intestine.

7. The Pancreas lies transversely in the lower back part of the epigastric region. It extends from the left hypochondriac region to the right side of the spine, and is placed behind the stomach, so as to be covered by it.

8. The Kidneys and the Capsulae Renales, two in number each, are placed in the posterior part of the lumbar region on the side of the spine.

9. The Urinary Bladder and the Rectum, in the male, occupy the cavity of the pelvis, and in the female between them are placed the uterus, the ovaries, and the vagina.

As, in the dissection of the abdominal viscera, the subject is commonly placed on its back, so the preceding description is made out with a strict reference to that position. Some modifi- cation in the shape of the abdomen, as well as in the situation of its contents, occurs in standing upright. The front of the abdo- men becomes then more protuberant, the lumbar vertebrae make a greater projection forwards. The pelvis is then so adjusted, in order to bring the acetabula directly in the Hne of support to the spine, that the convexity of the sacrum presents almost upwards, and the

16 ORGANS OF DIGESTION.

superior strait looks forwards and upwards towards the navel, SO that much of the weight of the viscera is thrown upon the pubes.. . In this attitude most of the viscera descend, but more obviously the liver, from its weight, size, and solidity. Portal has verified this descent by comparing the thrusts of poniards into the liver in the erect, with those inflicted in the horizontal position. He also asserts that the same may be ascertained in the living body by ap- plying the fingers under the false ribs, and then directing the per- son to change from the recumbent into the vertical position. The spleen affords the same results when it is slightly enlarged, and the descent of the liver and spleen will of course ensure that of the stomach and intestines. According to Winslow, the pain and faintness which are felt after a long abstinence, come from the vacuity of the stomach and intestines, which thereby' withdraw their support from the liver, and permit it to drag upon the dia- phragm.

The presence of flatus in the stomach and intestinal canal, seems to be entirely natural to them ; for it is comparatively rare to find them destitute of it, even when they contain no food or faeces. The large intestine is, however, more frequently found contracted or empty than the small. Owing to the flexible cha- racter of a considerable portion of the abdominal parietes, the lat- ter, by their own contraction, as well as by atmospheric pressure, are kept in close contact with the viscera ; and the viscera again, by the same influence, are kept in close contact with one another : so that, notwithstanding the irregularity of their forms and the fluctu- ating size of the hollow ones, there is no unoccupied space in the cavity of the belly.

Several instances are reported by anatomists, in which a total transposition of the abdominal viscera, has occurred, so that those which belonged to the right side were placed in the left.* They are, however, exceedingly rare. In the entire observation of my life, amounting to thirty years of anatomical study, and extending itself to many hundred bodies, I have not met with one instance of it.

* Portal, Haller, Sandifort, &c.

OF THE PERITONEUM. 17

CHAPTER III.

Of the Peritoneum, and Serous Membranes, Generally.

SECT. I. — OF THE PERITONEUM.

The sides of the abdomen are lined, and its viscera are covered by a membrane called Peritoneum. As the reflections of this membrane, by being thrown over the periphery of almost every viscus of the abdomen, consequently, assume the same shape ; and as it lines, without exception, the interior surface of every part of the abdomen, its form is extremely complicated, and can only be judged of accurately after the study of the viscera is completed. For the present it will only be necessary to give the outline of it, leaving the details to each appropriate occasion.

In man, it is a complete sac, having no hole in it; but in wo- man, its cavity communicates externally through the Fallopian tubes. It has a double use : In consequence of covering the vis- cera, it is so reflected from them to the sides of the abdomen, that its processes keep the viscera in their proper places, and, there- fore, answer as ligaments: again, its internal surface being smooth, indeed, highly polished, and continually lubricated by a thin, albu- minous fluid, corresponding with the synovial membrane of the joints, the motions which the viscera have upon each other in ex- ercise, and in the peristaltic action of the bowels, are much facili- tated.

The manner in which a double night-cap is applied to the head, will aflbrd the easiest conception of the reflections of the perito- neum. If there were only one viscus in the belly, and that of a somewhat regular outline, as the spleen, the comparison would be rigid, and perfectly appreciable. One part of the cap is close to the head, and compares with the peritoneal coat of the spleen ; the other is loose, and is equivalent to the peritoneum, where it is in contact with the parietes of the belly. It is also evident from this, that none of the viscera can be said to be within the cavity of the peritoneum ; that they are all on its outside ; and that a viscus, in

Vol. II.— 3

18 ORGANS OF DIGESTION.

getting a coat from the peritoneum, merely makes a protrusion- into its cavity. Starting with this simple proposition, it is easy to conceive of a second, a third body, and so on, deriving an external coat from a protrusion into the same sac. Admitting these bodies to be spheres, the proposition is imniediately intelligible; and, as a last step from it, the idea is not rendered much more complex by substituting any bodies even the most irregular in form, for these spheres.

Such, then, is the fact in regard to the stomach, intestines, 6z:c. ; they all, with the exceptions to be stated, derive an external coat from the peritoneum.

The Peritoneum is, for the most part, smoothly spread upon the interior surface of the abdominal muscles. It adheres to them with considerable firmness by means of intervening cellular sub- stance : this adhesion, where it closes the posterior opening of the umbilicus, is unusually strong. Below, the uniformity of the mem- brane as it descends from the navel to the pelvis is interrupted by its being reflected over the urachus, and over the remains of the umbilical artery on each side. Where the urachus is, it forms an oblong prominent ridge, reaching to the upper extremity of the bladder; and, as regards each umbilical artery, the duplicature is of a variable breadth in different individuals; but always forms a well marked falciform process, reaching from near the umbilicus to the lower side of the bladder, and dividing the inguinal region into two parts or fossae, one next to the pubes, and the other near to the ilium. In the undistended state of the bladder the perito- neum reaches to the pubes, is reflected from the latter to the upper, and then goes over the posterior surface of the bladder. In the male, it goes from the posterior lower end of the bladder to the rectum, but, in the female it does not descend so low there, and passes from the bladder to the vagina and uterus, and afterwards to the rectum.

In the concavity of the ilium, and in the lumbar region, the peri- toneum is attached by long loose cellular substance, which permits it to be stripped ofl" easily, simply by tearing. In these several regions it encounters the colon, over which it is reflected, and thereby forms the Mesocolon ; thence it passes in front of the kid- neys, but separated from them by a thick layer of cellular and adipose matter, and immediately afterwards it is thrown into a long duplicature, extending obliquely across the lumbar vertebree

OF THE OMENTA.

19

from above, downwards, and to the right side. This duplicature includes the small intestine, and is the Mesentery.

In the highest regions of the abdomen, the peritoneum is in the greater part of its extent uniformly reflected over the concave sur- face of the diaphragm, and adheres so closely to it, as to require a cautious and protracted dissection for its entire removal. As the remains of the umbilical vein of 'the foetus are still found, but in a ligamentous condition, going from the navel to the under surface of the liver, their existence gives rise to the falciform ligament, a broad duplicature of peritoneum, which passes from the upper half of the linea alba and from the middle line of the diaphragm to the liver. Another line of attachment, or of reflection, of this mem- brane to the liver, is found all along the posterior margin of the latter. In the same region, it is also reflected from the diaphragm to the spleen and to the stomach. Such is the general account of the course of the peritoneum. Each of the duplications has a dis- tinct name, and some peculiarity of organization or of relation, which will require a specific description and a frequent allusion to it.

It is proved, from what has been said, that the peritoneum is a single and complete sac, and that, with the exception stated of the Fallopian tubes, there is no hole in it either for the passing of blood vessels, nerves, or viscera. And that it is so folded over the abdo- minal viscera, that with patience and sufficient address, one might remove it from their surface and extract them, without even laying open its cavity: an experiment said to have been successfully ac- complished by Nicholas Massa,* and some other anatomists.

SECT. II. — OF THE OMENTA.

There are four processes of the peritoneum, each of wh'ich is designated under the term Omentum, Epiploon, or Caul.

1. The Omentum Minus or Hepatico-Gastricum, extends, as its name imports, between the liver and the stomach. It begins at the transverse fissure of the liver, and proceeds from it, from the right side of the lobulus spigelii, the front of which it conceals,

* Anat. Liber. Introduct. an. 1539. Portal.

20 ORGANS OF DIGESTION.

and from the inferior posterior face of the tendinous centre of the diaphragm ; it is attached to the lesser curvature of the stomach in all the space between the cardiac and the pyloric orifice. Its right margin reaches beyond the pylorus to the duodenum, and includes the vessels going to the liver, and the biliary ducts; in consequence of which, this margin is called the Capsule of Glisson. The capsule is, however, more properly the condensed cellular substance within.

The two laminae which compose the omentum minus are thin and transparent, and have but little fat in them ; in approaching the stomach they become very distinct from each other, and re- ceive between them the superior coronary vessels of the stomach. One lamina then goes before the stomach and the other behind, in the form of a peritoneal covering. These laminos, having covered in that way the anterior and the posterior surface of the stomach, unite again on the greater curvature of the latter, to form the be- ginning of the omentum majus.

2. The Omentum Majus or Gastro-Colicum, as indicated by its name, is connected at one end all along the greater curvature of the stomach, and by the other along the transverse part of the colon. As it commences by two laminse, so it is continued through- out in the same way. It is commonly found more or less spread on the front surface of the small intestines, but occasionally it is tucked up in the epigastric region. When fairly spread out, either naturally or artificially, its course will be found as follows : It first of all descends from the stomach to the pelvis ; it then turns up- wards, so as to reverse its course, and continues to ascend till it reaches the colon. Its two laminae then separate and receive the colon between them, so that, in this respect, the arrangement is entirely conformable to what happens to the stomach. The sub- sequent continuation of these laminae is the mesocolon, which will be more particularly described.

As the omentum majus consists of two laminae in its whole ex- tent, it is clear that it resembles a flattened bag lined by another bag ; so that in its whole thickness, when held between the fingers, there are four laminae. It is an irregular quadrilateral membrane, which, in corpulent subjects, is interspersed with a great deal of fat; but in such as are emaciated, it is w^holly destitute of the lat- ter ; and instead of being entire in its parietes is a delicate reticu-

OF THE OMENTA. 21

lated membrane, so that the rule about the integrity of the perito- neum is not fully accurate as appHed to this section of it. On the right side it is continuous with the omentum coHcum, and on the left with the omentum gastro-splenicum.

3. The Omentum CoHcum may be considered as a continuation of the omentum majus along the ascending and a part of the trans- verse colon. In some rare cases, (for in my own observations I have not met with the arrangement,) its origin is continued down- wai'ds to the coecum, and at its left margin is extended along the transverse colon to the spleen. Much more commonly it is, as stated, simply an appendage of the great omentum, or its right flank, advancing for a short distance along the ascending colon.

It consists of but two laminae in all, commonly containing fat, but in this respect subject to the same rule as the omentum majus.

4. The Omentum Gastro Splenicum is the left flank or margin of the omentum majus, extended from the great end of the stomach to the spleen. It of course consists of but two laminae, which con- tain between them the splenic vessels and the vasa brevia.

By looking for the posterior end of the gall-bladder, and then passing a finger under the right margin of the hepatico-gastric omentum, or in other words, under the capsule of Glisson, where it extends from the liver to the duodenum, the finger will be found to have insinuated itself behind the stomach, and, by being directed downwards, will be thrust into the sac or cavity of the great omentum. In children, where the latter is less reticulated than in adults, and consequently more entire, a large blow-pipe intro- duced at the same point will enable one to inflate this cavity, and to separate its anterior from its posterior wall. This aperture, called the foramen of Winslow, is the route by which the internal or lining lamina of the omentum majus is introduced, so as to make this process of peritoneum double throughout its whole parietes. Though this fact of duplicity is generally conceded, no author heretofore, to my knowledge, has pointed out satisfactorily the means; and for the suggestion of it, I am indebted to a learned and zealous member of the profession, now Professor Hodge of the University. Struck, at an early period of his studies, with the difliculty of tracing a double sac to the omentum majus, out of a

single membrane of the peritoneum, this suggestion was happily

3*

22 ORGANS OF DIGESTION.

made by him to remove the difficuUies of other explanations. An attempt at a diagram formed upon any other principle I have in- variably seen to fail. If the reader has conceived the idea, the inference will be plain, that the lining lamina of the omentum majus is continued as a common peritoneal covering over the pos- terior face of the stomach, and then forms the posterior lamina of the hepatico-gastric omentum. It will also be plain that the same lamina, having reached the colon in its return, continues after- wards as the upper lamina of the transverse mesocolon.

From what has been said concerning the general qualities of the peritoneum, it is to be understood that though it enjoys much power of gradual extension, nevertheless this quality is not suffi- cient to enable it to endure, without a special provision, the sudden and extensive dilatations to which the stomach and bowels are exposed, from the introduction of food and from the evolution of gases during digestion. Of all the coats of these organs, it is the least extensible and contractile; its rupture, therefore, is guarded against by one invariable rule. For example: as the muscular and other coats of the stomach dilate, the peritoneum is drawn from the omentum minus and majus to cover the stomach ; there- fore, as the stomach enlarges, the omenta diminish: and as the stomach decreases, the omenta, by the restoration of peritoneum, resume their primitive size. In this way the uterus, notwithstand- ing its great augmentation in the progress of pregnancy, still keeps itself covered by peritoneum, from the ability of the latter, as men- tioned, to slide from one part and to apply itself to another. The true intention, then, of the apparently useless length of many pro- cesses of the peritoneum, is explained, by their being a provision for the augmentation of the hollow viscera of the abdomen, in the discharge of their natural functions. Adopting this explanation as the basis of our observations, we shall find that according to the probable or even possible augmentation of a viscus, so are its peritoneal attachments. The stomach, which next to the titerus enlarges more than any other viscus, gets its subsidiary supply of peritoneum from the length of the omentum minus and majus; the colon, which is next in order, is supplied from the length of its mesocolon ; the small intestines, which are next, from the length of the mesentery. The latter, however, would be too long for that simple purpose; but the objection is removed by recollecting that the mesentery has also to accommodate numerous chains of

OF THE OMENTA.

23

lacteal glands, through which the chyle must pass in its elabora- tion, before it is fit to enter into the general circulation. The liver, being of a size almost stationary, has its peritoneal attach- ments proportionally short; and its peritoneal covering, from the shortness of the connecting cellular substance, is disqualified from sliding. The spleen is in the same predicament with the liver, except that its size is not stationary ; but, in this case, the perito- neum presents a phenomenon entirely remarkable: it wrinkles upon the contraction of the spleen.

If this mode of reasoning, derived, from an arrangement of parts which no one denies, be correct, it follows that physiologists have erred sadly in the supposed uses of the omentum majus. That this organ is, in fact, only subsidiary to the enlargement of the stomach and colon, so as to prevent the rupture of their peritoneal coat, and that it is neither intended to keep the belly warm, as so learned a naturalist as M. G. Cuvier has suggested,* nor is it a special store-house for the wants of the system during the destitu- tion of other aliment, farther than adipose matter in other parts of the body is.f In regard to the first theory, it does not appear that the inhabitants of cold climates are better furnished with an omen- tum majus than those of the torrid zone : that it is better developed in winter than it is in summer; that it is tucked up in warm weather to cool the intestines, or spread out in cold weather to make them more comfortable. On the contrary, it is ascertained that its position is variable at all seasons; that in the coldest of weather it is as often found collected in the epigastric region, or to one side of the abdomen, as it is in the warmest ; consequently, its position is the result of whatever motions may, for the time, havetbeen impressed upon it by the distention of the stomach,, and. by the peristaltic movements of the bowels. In regard to the theory of Dr. Rush, the objection is insurmountable, that children, who are equally, if not more exposed to starvation and sickness than adults, never have fat, except in very small quantities, in the omentum, and that only along the course of its vessels. The fat is, therefore, not to be viewed as an essential circumstance in the structure of the omentum, as all children and many adults have it only very sparingly ; for the omentum being wanted as a mem-

* XXII. Legon D'Anat. Comp.

t An Inquiry into the Uses of the Omentum, by James Rush, Philad. 1809.

24 ORGANS OF DIGESTION.

brane of reserve to the stomach and colon, the deposite of fat in it, is in obedience to one of the general laws of the system, whereby the cellular substance beneath the serous membranes is disposed to secrete fat as the individual advances in life; which is exempli- fied on the h^art and in the pleura. Another argument is, that in the ruminating animals, where there are four stomachs, and from the vegetable nature of their aliment these stomachs must, in the course of digestion, be very much distended, the great omentum is of proportionate magnitude.*

As occurs in other parts of the body, also, the fat of the omen- tum accumulates in animals that take but little exercise, while it is very deficient in such as lead an active life.

I am induced to believe that the hard knots felt in the abdomen of such persons as suffer from abdominal affections, frequently de- pend upon the accumulations of the omentum majus at particular but variable points.

SECT. III. — GENERAL ANATOMY OF THE SEROUS MEMBRANES.

As the peritoneum presents one of the best examples of a nume- rous class of membranes, called Serous, it will be useful at this point to inquire into their general condition and properties. They are, for the most part, thin, and strongly resemble compressed cel- lular membrane; having been, indeed, by some anatomists, con- sidered as such. They invariably assume the form of perfect sacs, and as they are found in all parts of the body, they are kept dis- tinct from each other. The arachnoid membrane of the brain, the pericardium, the pleura, the synovial membranes of the joints, the bursse mucosae of tendons, the peritoneum, and the tunica vaginalis testis, belong to this class. They are not all of the same thickness, as some are much more dense than others; they adhere to neigh- bouring parts by a lamina of cellular substance, which is also of variable thickness and ductility; indeed, on some occasions, it is not entirely distinct, from its extreme shortness and tenuity.

As the serous membranes are only displayed over the surface of the organs which they cover, after the manner of a double night- cap drawn over the head ; their cavity always remains entire, not-

* Cuvier, XXII. Lejon, loc. cit.

ANATOMY OF SEROUS MEMBRANES. 25

withstanding it is variously modified by the shape of the organs protruded into it; and has its parietcs in contact, owing to external compression. They are entirely distinct from the essential struc- ture of the organs covered, and are displayed over those of the most dissimilar functions, as, for example, the intestines and the liver. A sac of this description, then, is of infinite importance in establishing betvi^een organs which border upon one another a strong partition : and, consequently, in warding off any injurious influence which their dissimilar natures would otherwise cause them to have upon each other. Important organs are, therefore, invariably thus insulated, so that whether in a healthy or in a dis- eased state, their actions are carried on within themselves; and not only so, but it is even possible, and, indeed, is found in morbid dissections, every day, that an organ may be diseased while its serous covering is unaffected ; or the reverse. Thus, we have large suppurations in the liver, while its peritoneal coat is healthy; large accumulations of water in the tunica vaginalis testis, while the testicle itself is sound ; in the thorax, with sound lungs and heart; in the abdomen, with viscera generally sound; in the joints, without an afl^ection of the bones. Nothing is more common than to see partial adhesions, the result of inflammation, causing the opposite sides of these sacs to adhere, without any evident consti- tutional or visceral derangement; and some of our plans of cure, as in the hydrocele, are founded upon this well established fact.

The serous membranes are throughout thin, transparent, and white: in some points their tenuity is so extreme that they seem to consist simply in a smooth, polished surface, spread over parts; this is strikingly the case on the interior face of the dura mater, on the ventricles of the brain, and on the cartilages of the joints. The evidence of their extension there, is consequently derived principally from induction; and from morbid alteration, in which they become thickened. Their internal surface in a natural state, is always smooth, highly polished, shining; and, being also lubri- cated by its peculiar unctuous secretion, the opposite parietes, when they come into contact, glide freely upon each other; a cir- cumstance indispensable to the free action of the joints, and to the peristaltic motion of the bowels. Bordeu has asserted, that these remarkable characters of the serous membranes depend upon the compression and the friction to which they are continually exposed: but to this opinion the argument of Bichat is unanswerable, that

26 ORGANS OF DIGESTION.

in their earliest observable period in the foetus they have the same polish.

The fluid secreted from the serous membranes resembles, strongly, the serosity of the blood. It is poured out continually by the exhalent orifices, and in a short time afterwards is taken up by the absorbents ; so that in a natural state there is seldom more than sufficient to lubricate the surface of the membrane. When the abdomen of an animal recently killed is exposed to the air, this fluid rises in the form of a vapour. The several experi- ments, as the application of heat, mineral acids, and so on, which prove the abundance of albumen in the serum of the blood, pro- duce the same results when applied to the secretion from the serous membranes.

The system of serous membranes has been considered by Bichat and others, as only a modification of cellular membrane, for the following reasons. The inflation of air into the cellular tissue sub- jacent to them, reduces them to the form of cellular substance. Protracted maceration produces the same effects with more cer- tainty and precision. When cellular membrane is inflated, the parietes of the distended cells resemble strongly the finest parts of the serous system, as the arachnoid membrane. There is an identity of functions and of affections, for they are both .conti- nually engaged in the great work of exhalation and absorption, and suffer in the same way from dropsical effusion, with the only difference that the latter is more amassed in the one than in the other. My own experience goes to prove, that dropsy very sel- dom manifests itself, to any extent, in the cellular tissue without also going to the serous cavities, and the reverse. The serous membranes are also of a uniform texture, like cellular substance, and present no appearance of a fibrous matter.

The serous membranes are furnished with a great abundance of exhalent pores, and of absorbents, which carry on their func- tions with great activity. They, when healthy, receive only the colourless part of the blood, whence the uniform transparency of these membranes. The existence of exhalent pores, is proved by strangulating a piece of intestine with a ligature for thirty-six or forty-eight hours, when they become evident, by dilating them- selves so as to receive red blood. A fine coloured injection pro- duces the same result; and also moistens, by the escape of its watery particles, the surface of the intestine, by a very fine halitus

ANATOMY or SEROUS MEMBRANES. 27

or dew. The intestine of a living animal, if wiped perfectly dry, will, after the same way, soon present another coat of serosity on its surface. The existence of absorbents to a great extent in them, may also be equally well proved, as they very readily receive a mercurial injection, which diffuses itself over their whole surface, and causes them to have the appearance of being formed entirely of such vessels. The readiness with which fluid effused into their cavities is taken up, is another proof of the same. Bichat once saw them distended with air in a man who had become emphyse- matous from poisoning. Mascagni has frequently found them dis- tended with the fluid of dropsical collections, which he recognised by its colour. It happened to the same anatomist to find in two bodies, where there had been an eff'usion of blood into the thorax, the absorbents of the lungs gorged with blood. This faculty of absorption may sometimes be proved to continue for some hours after death, by keeping an animal in a warm bath. Mascagni asserts, that he has witnessed its continuance for fifteen, thirty, and even for forty-eight hours; it is not improbable, however, that there was some illusion in these instances.

It is more than probable that the serous membranes are entirely deprived of red blood vessels ; the latter unquestionably exist, in great numbers, on the exterior surface, where they creep through the cellular substance, but they may be removed with a scalpel without affecting the continuity of these membranes. Again, where these membranes are free and unconnected on both sur- faces, as in some parts of the tunica arachnoidea, there is no ap- pearance of red blood vessels. In hernial protrusions, where there is a considerable prolapse of peritoneum, the blood vessels which are found abundantly about the neck of the sac do not follow the course of the protrusion. Unquestionably some communication exists between the arterial system and the serous membranes, as proved by exhalation and morbid phenomena, but the mode is not well ascertained. We learn, however, upon the authority of Miil- ler,* that there are some preparations of the peritoneum by Bleu- land at Utrecht, leading to a different conclusion — and that there are some also by Der Kolk, of the same membrane, which prove indubitably that this membrane contains vessels.

In common hernia and in dropsy, the serous membranes become

Phys. p. 226.

28 ORGANS OF DIGESTION.

more thick : from my dissections I am inclined to think, that this change is not so great as is generally allowed; for most frequently, by a careful removal of the exterior cellular substance, they have been restored to their primitive condition. In other cases, as in large umbilical hernias, they are so much attenuated as to be found with difficulty.

The power of extension which these membranes possess, is strikingly marked in dropsical effusions, in the development of tumours, and in pregnancy ; but much of this apparent quality is derived from their mode of attachment to adjacent parts, whereby they are drawn from one surface to cover another. This happens daily where the peritoneum is drawn from the lower part of the abdomen to cover the bladder in the distentions of the latter; in pregnancy, where it is drawn upon the growing uterus from all the neighbouring parts; and in the distentions of the stomach by food or flatus, where it is drawn up from the omenta. The serous membranes have also a power of contraction equal to that of their extension; but it should not be confounded with that condition where they are simply restored by the connecting cellular sub- stance, to the surfaces to which they originally belonged.

The sensibility of the serous membranes, from the want of nerves in them, is extremely obscure in a natural state, and only affords an imperfect sensation of touch. This is proved by the impunity with which they may be irritated on living animals. But, when the condition of inflammation is once established, they feel the most acute and distressing pain. Though they resist most frequently, and for a long time, disease in adjacent parts, yet it not unfrequently is extended to them at last. In such cases, it is generally a local instead of a universal affection, which is com- municated to them: Thus, in the cancer and scirrhus of the uterus; in disease of the spleen, and so on; the portion of peritoneum nearest the affected organ manifests the marks of the disease by preterna- tural adhesions and by disorganization, without the whole mem- brane being involved.

As the serous system consists in many species of sacs, so each o{ them has some peculiarity of organization, of attachment, and of vital properties, which is stated elsewhere in the account of the species themselves.

The microscope has proved that notwithstanding the extremely polished surface of the free side of the serous membranes, yet they

THE STOMACH. 29

are covered by an epithelium. This epithelium has been found on all except the subcutaneous bursa3. The epithelium of the serous cavities is, like the epidermis, formed of flattened scale-like cells, which are, for the most part, polygonal or tesselated, like a pave- ment made of hexagonal bricks, and have each a nucleus in their centre. Some of these cells are furnished at their edges with minute hair-like filaments called cilia, which, during life and for some time after death, are in a slate of continual whirling or vibration, and as is supposed, for the purpose of preventing a stagnation of the fluids in contact with them. These cilia are especially numerous and active in the ventricles of the brain. In some places the epithelium is found without the serous mem- brane beneath, hence it is inferred that the latter is not so essen- tial as the former in the character of such membranes.

Epithelia being always in contact with fluids, they diflTer from the cuticle in being pliant and humid, but are restored with equal facility when they are lost by abrasion or inflammation.

CHAPTER IV. Of the Chylopoetie Viscera.

SECT. I. — OF THE STOMACH.

The Stomach {Ventriculus, Stomaclius) is a hollow viscus situ- ated in the epigastric region, intended to receive at one end ali- mentary matters from the oesophagus, and to transmit them, at its other extremity, after dii^estion, into the intestinal tube, where the nutritious part of the food is absorbed into the circulation. It is a conoidal sac, curved considerably upwards, and presents two Faces, two Orifices, two Curvatures, and two Extremities.

The Faces of the stomach are, from their position, named ante- rior and posterior, or, one presents to the linea alba and the other towards the spine. The flat configuration is rendered more ob- vious when the organ is empty; for when distended it is rounded,

Vol. II.-4

30 ORGANS OF DIGESTION.

and the anterior face is caused to look forwards and upwards from the resistance of the spine behind, while the posterior is of course in an opposite direction. In other respects they do not present any thing worthy of particular attention.*

The two Orifices of the stomach are named Cardia and Pylorus. The first or Cardia is at the left and most superior part, but re- moved to the distance of two inches or more from the left extre- mity. It is generally considered a smooth uninterrupted continua- tion of the oesophagus into the stomach, immediately after the oesophagus has passed through the diaphragm into the abdomen. But in a preparation,! of this organ, made by drying, and now in the anatomical cabinet, a circular rounded pad is very perceptible at the cardiac orifice ; being elevated two lines or more all round, so that it makes a perfect ring of from eight to twelve lines broad at its base. This pad seems to be composed of a cellular sub- stance, which is almost perfectly white, elastic, and consists of the finest filaments, resembling carded cotton: it is placed between the lining membrane of the cardiac orifice and the adjoining coat.

The Pylorus, when viewed externally, looks like a smooth con- tinuation of the stomach into the duodenum ; but when felt, there is a manifest thickening of the part, depending upon a structure to be presently explained. It points upwards and to the left side, but is, by the whole thickness of the liver, lower down than the cardia.

The two Curvatures are designated the great and small, or the upper and the lower. The first, forming the upper margin of the stomach, is bounded at its extremities by the orifices, and is very concave; its curvature is maintained both by a natural configura- tion and by the small omentum. The great curvature forms the whole inferior periphery of the organ, extending also from one orifice to the other. When the stomach is flattened, these curva- tures form very evident boundaries to the anterior and the poste- rior faces.

The Extremities of this organ are singularly different in size. That on the left forms the base of the cone, or the large extremity, and projects considerably beyond the cardia towards the spleen.

* In some cases the posterior face of the stomach is concave to accommodate it to the spine : this is best seen on inflation and drying. + Made December, 1828.

THE STOMACH.

31

It is a rounded cul-de-sac, or tuberosity, the dimensions of which will, of course, vary according to the state of distention. The right extremity, on the contrary, is produced by a gradual diminu- tion of the organ from its middle to the duodenum. When the stomach has approached within an inch or two of the latter, it suffers a sort of constriction, which gives to the right end a more cylindrical shape. This part is sometimes called the Little cul-de- sac, or the Antrum pylori.

Where the stomach has been kept empty for some time pre- viously to death, it is found not much larger than an intestine; its variable magnitude, therefore, prevents any very rigid rule of di- mensions from being applied to it; most commonly, however, we find it between the capaciousness of a pint and a quart measure.

It is retained in its situation by its continuity with the oesophagus and duodenum ; also by the hepatico-gastric, and the gastro-splenic omentum. It is in contact above, at its lesser curvature, with the diaphragm, the left lobe of the liver, and the lobulus Spigelii; at its great extremity with the spleen, at its posterior face with the pan- creas, and at its greater curvature with the colon and the meso- colon.

The stomach is formed by four Coats or lamin£e,of a character essentially differing from each other : The Peritoneal, the Muscular, the Nervous, and the Mucous.

The Peritoneal Coat envelops the stomach completely, and ad- heres closely, except at the curvatures, where, as has been men- tioned, a provision is made for the distention of the organ, by the looseness and the separability of the attachment of the two laminae of the omentum minus and of the majus. An uncovered space will, consequently, be found between the laminae at these places, along which the vessels run that furnish the stomach. The peri- toneal coat is very thin, and is attached to the subjacent muscular, by very fine cellular substance, which permits it to be raised from the muscular by a careful dissection. In a dried preparation which I made,* there is an exhibition of minute foramina of the peritoneal coat, in apposition as close as the follicles of the mucous coat.

The Muscular Coat is intermediate in thickness to that of the intestines and of the oesophagus, but its fibres are pale, are col- lected into flattened fasciculi, and go in three directions. The

» In 1839.

^2 ORGANS OF DIGESTION.

most superficial are a continuation of the longitudinal fibres of the oesophagus, and are less numerous and less uniform in their distri- bution than the circular fibres. The greater part of them forms a flattened broad fasciculus, which extends along the lesser curva- ture of the stomach, from the cardiac to the pyloric orifice. A thinner and less distinct fasciculus may be traced over the great cul-de-sac, and somewhat indistinctly, along the greater curva- ture; and a few others may be seen on the anterior and posterior faces of the stomach, forming- rather a fine linear or striated appearance than a perfect lamina ; this linear appearance is well exhibited by an oblique reflection of light from it. The second series consists in a lamina of circular fibres distinctly covering the whole surface of the organ. They are not so numerous near the cardia, but become more abundant as they are examined towards the pylorus, in the vicinity of which they are multiplied so as to form a lamina of two lines or more in thickness. The circular fibres are parallel with each other, and, when the stomach is much distended, their fasciculi separate so as to leave interstices between them in many places. The individual fibres do not surround en- tirely the stomach, but are rather segments of circles. The third and deepest series of fibres, constituting the muscle of Gavard, from their discoverer, may be called oblique, and are arranged into two broad flattened fasciculi, one of which is placed to the left side of the cardia, and is prolonged over the anterior and the pos- terior faces of the stomach; while the other, being to the right of the same orifice, is extended over the anterior and the posterior faces of the cul-de-sac, where it supplies the want of transverse or circular fibres: this series may be considered as a continuation of the circular fibres of the oesophagus.

The Nervous or Cellular Coat (Tunica Propria) connects the muscular with the mucous. It is formed by a compact, thick, and short cellular substance, which, when inflated and dried, looks like carded cotton. It contributes much to the general strength of the organ, and serves to conduct the blood vessels and the nerves to the mucous coat.

The Mucous or Villous Coat is the most internal, is not quite a line in thickness, and can be readily raised up by dissection. In an undistended state of the stomach it is arranged into a number of wrinkles, which are very irregular in their form, size, and direc- tion, but disappear immediately on distention, or at least leave but

THE STOMACH.

33

very faint traces. It is continuous with the internal membrane of the oesophagus and of the duodenum, but presents a surface differ- ing from either of them, and which is rendered very apparent by floating it in water. The epidermis, which is continued along the internal face of the oesophagus, ceases as mentioned around the cardiac orifice, and, by a slight maceration, may be raised up and demonstrated to terminate there. An epithelium under modified circumstances is then found to start and to cover the entire inte- rior of the stomach, and to be continued over the intestinal canal from one end to the other. It is softer, thinner, and more spongy than the common epidermis of the pharynx and oesophagus, but may be proved to exist by the microscope, by the exfoliations in scales formed in the fa3ces, and also by insufflation, when it will be raised and may be dried in that state.

This mucous membrane or coat, the office of which is to secrete the gastric juice for the digestion of articles of food, presents a surface that resembles very much common velvet, from whence the term villous is applied to it. If it be perfectly healthy, and the individual died suddenly a few hours after eating — it is found of a uniform light pink colour, without blotches or any thing of extravasation under it. This fact I have had several opportunities of verifying, by experiment and by autopsies :* And more lately in the person of a criminal, Williams, executed for murder.f It is usual, to find it, if examined a short time after death, having, particularly along the smaller curvature and at the great end, a pink and sometimes a deeper colour, produced by an accumulation of blood in its veins.

The texture of this membrane is soft, loose, and easily lacerated. When floated in water and examined with a magnifying glass, it is found to have a superficial honey-comb arrangement, and to be studded with a multitude of small follicles or orifices. In the vicinity of the cardiac and of the pyloric orifice, the same arrange- ment is more obvious, and conducts to some small muciparous glands, which are more or less apparent, and called the glands of Brunner.

At the junction of the lesser extremity of the stomach with the

* See Amer. Journal Med. Science?, Vol. 1. 1827. Horner's Pathol. Anal. p. 195, &c. t Aug. 9, 1839.

4*

34 ORGANS OF DIGESTION.

duodenum, the internal membrane is thrown into a circular dupli- cature constituting the Pyloric valve, and abridging the size of the orifice. It is seen most favourably in the distended and dried state, and then presents a sort of septum not unlike the form of the iris. Around the external periphery of this ring, the circular mus- cular fibres have a sudden augmentation of number, which gives them, when viewed from the duodenum, the appearance of a dis- tinct circular muscle, occasionally called the muscle of the pylorus, but it does not exist in a state so separate as this name indicates. The opening of the pyloric valve is generally circular, but some- times ovoidal, and it is sometimes to one side.

It is very common to find the stomach divided as it were into two compartments, by a contraction of its middle, resembling that of an hour glass. It is said that this occurs habitually during digestion; in my personal observations, however, I have seen the stomach more frequently in this state when it contained nothing, not even air, than when articles of aliment were in it.

The stomach is extremely vascular. Its arteries, being branches of the Cceliac ; are the Gastric, the Right, and the Left Gastro- Epiploic, and the Vasa Brevia. The first goes along its lesser curvature, the second and the third along its greater curvature, and the last, from four to six in number, go to its great cul-de-sac. They all approach it between the laminae of its omenta, and un- dergo many divisions and subdivisions in the cellular coat ; they at length terminate by forming a very fine and delicate vascular arrangement in the substance of the mucous membrane, and when successfully injected give to the latter a thorough tinge of red. The veins follow the course of the arteries, and like them have frequent anastomoses, but are larger; they terminate either directly or indirectly in the trunk of the Vena Portarum.

The nerves of the stomach come from the Par Yagum, and from the semi-lunar ganglions of the Sympathetics.

Its lymphatics arise from both the external and the internal sur- face, and their trunks having to pass first of all to the lymphatic glands situated along the curvatures, afterwards empty into the thoracic duct.

INTESTINAL CANAL.

35

SECT. II. — OF THE INTESTINAL CANAL.

The Intestinal Canal is from thirty to thirty-five feet in length, and extends fronn the pylorus to the anus. Owing principally to a well marked difference in magnitude, it is divided by anatomists into the Small and into the Large intestine.

Of the Small Intestine.

The Small Intestine {Intestinum Tenue) commences at the py- lorus, and terminates in the right iliac region by a lateral aperture into the large intestine. It is four-fifths of the length of the whole canal, and measures from twenty-four to twenty-eight feet.* When moderately distended its diameter is about one inch. It retains from one end to the other an uninterrupted cylindrical shape, with the exception that if the two ends be compared, the upper will be found larger than what is stated as the medium measurement, and the lower smaller ; by which arrangement it will be found that the intestine decreases successively from above downwards, and, as a whole, is slightly conoidal or spindle shape, though this dimi- nution is so gradual that it is not perceptible in any short space.

The small Intestine, like the stomach, consists of four distinct coats, the peritoneal, the muscular, the cellular, and mucous.

The Peritoneal Coat is complete, and forms the external surface. It is continued afterwards in two laminae from the intestine to the lumbar vertebrae, thereby constituting the Mesentery. The two lamince, where they depart from the intestine, are loosely connected with each other, for the purpose of allowing room for the dilata- tion of the intestine, on the same principle which is exemplified in regard to the stomach.

The Muscular Coat is next to the peritoneal. Its fibres are pale, and form a lamina not so thick as common writing paper. The

» This is the generally received opinion of anatoniisls : it would appear, however, to be applicable only when the intestine is left attached to the mesentery ; for if it, be cut off and straightened, it will measure thirty. four feet, which, added to eight feet of large intestine treated in the sanne way, will amount in all to forty-two feet. If to the estimate of this length we add what is lost by the doublings of the mucous coat, the entire length of surface must amount to nearly sixty feet, at least, in many subjects.

36 ORGANS OF DIGESTION.

superficial ones are longitudinal, not very distinct, and too much separated to form a perfect coat: they are most abundant on the anterior semicircumference or the one most distant from the Mesen- tery. The others all run in a circular direction, approaching to the spiral, and are sufficiently numerous to form a perfect coat: none of them perform a complete circuit of the intestine, but are rather segments of circles. This coat is united to the peritoneal by a thin scattered cellular substance.

The Cellular Coat of the small intestine, (Tunica propria) also called the Nervous, like that of the stomach, is only a lamina of dense cellular substance, which serves as a medium of connexion between the muscular and the mucous coat ; and also conducts to the latter the blood vessels, nerves, and lacteals. When inflated and dried, it puts on a beautiful cotton-like appearance — just as the corresponding coat of other parts of the alimentary canal does under the same treatment.

In the lion this membrane presents a most elegant clear tendi- nous appearance, and is so strong that it will bear, from the inte- rior, the pressure of a column of water eighteen feet high. The muscular and peritoneal coats splitting open, while it remains entire. Under this strong pressure of water neither the lacteals nor blood vessels are filled with it, which goes to prove that the intro- duction of articles into them, from the intestinal cavity, is a vital and not a physical action.

The Mucous Coat is the most internal, and when it has been cleaned by maceration, exhibits an opaque pearly colour. It is remadiable for having its extent very considerably augmented beyond that of the other coats; by being thrown into a great num- ber of permanent folds, or duplicatures, which lie one upon ano- ther successively, like the shingles upon the roof of a house. These duplicatures are the Valvulce Conniventes, and are for the most part about three lines in breadth. They are either placed in the direc- tion of the circumference of the intestine, or are very slightly ob- lique ; generally they go all around, but many of them are segments of circles, and by being arranged successively, their ends pass one another, or are connected by slight elevations. They are more numerous and broad in the upper than in the lower half of the intestinum tenue, and are evidently intended to retard the progress downwards of alimentary matter, and to increase the surface for absorption and for exhalation.

INTESTINAL CANAL. 37

The mucous membrane, on the side which it presents to the cavity of the intestine, is furnished with a great number of deHcate cyhndrical projections, resembhng the down on the sl^in of an unripe peach, and called ViMi,* from whence the term villous has also been applied to this coat. These villi are to be found in abundance every where; but in the upper half of the intestinum tenue they are so numerous as to stud its whole surface, and to be in contact with each other. They are from one- fourth of, to a line in length; and some of them, when examined with a micro- scope, appear flattened and fungiform. According to the estimate of Meckel,! where they are thickest, every square inch of intestine furnishes about four thousand of them, and by extending this com- putation, with a proper allowance for diminished numbers below, their aggregate amount is about one million. J

Each Villus is composed of an artery, a vein, and a lacteal absorbent ; all united by cellular substance. From the extreme vascularity of the mucous membrane, the blood vessels readily receive a fine injection and thereby become evident, forming a very delicate vascular net-work in each of the villi. It is gene- rally believed, that the absorbent opens on its surface, but whether by one or more orifices is yet unsettled. According to the cele- brated Lieberkuhn, there is commonly but one orifice at the end of each villus, and very rarely two : this assertion he considered him- self as having established by passing a current of air through the villus till it was dried, and then slitting it open. Hewson, Cruik- shank, and W. Hunter, on the contrary, are said to have found many more, amounting even to twenty, on such villi as were gorged with chyle. The subject has been fruitful in controversy to anatomists, and ranks many distinguished champions on each side; but from the minuteness of the parts under discussion, it is exposed to much fallacy and illusion; and is not as yet fully settled. The more important fact, however, is conceded by the admission of all. that there is a branch of the absorbent system in every

* This is intended merely as an expression of the common and received notior>, my own views are exhibited in the minute anatomy of this coat. Sect. hi.

t_ Manuel D'Anat.

t This is probably much below their real number; in an observation at the uni- versity we have found the villi on the ileum at its lower part amounting to six thou- sand four hundred to the square inch, but as their shape varies very much, as we shall see; a rule cannot be derived from their shape.

ORGANS OF DIGESTION.

villus; and which has, for its function, the absorption of chyle from the cavity of the intestine.

A more recent observation has been made by Professor Krause, and reported in Miiller's Archives for 1837. In the body of a young man who had been hung after taking a full meal, he found the villi of the jejunum beautifully filled with chyle. The lacteal of each villosity arose by several branches, of which some termi- nated by a free extremity, and others by anastomosis with each other. Judging from his plate, he does not appear to have traced any branch to the surface of the villus. Miiller says, that he him- self had never seen any opening at the extremity of the villi. This corresponds with my own experience, as I have, also, in one case had a fine opportunity of seeing them distended with chyle. The villi, however, under any circumstances, cannot be considered as the sole organs for the absorption of chyle, for in many animals they do not exist.* A more calm inquiry into this matter will, probably, bring us all to the conclusion, that the villi exercise a tactile more than an absorbing power, which office their strong analogy with the papillae of the cutis vera strongly points out.

An abundance of Mucous Glands is found deposited in the cel- lular coat of the small intestine, between the muscular and the vil- lous ; their ducts open upon the internal surface of the latter, in the interstices of the villi, and from their smallness require the intes- tine to be floated in water, and examined with a magnifying glass, before they can be recognised. In order to see the glands them- selves, the intestine must be cleaned by soaking it in water; it is then to be slit open longitudinally, and held between the eye and the light, in which case the glands appear like little points or spots in the thickness of the intestine. They are more abundant in the beginning of the latter, decrease about its middle, and increase again towards its termination. Their structure is very simple, as they consist in a congeries of blood vessels, terminating in short canals secreting mucus. f

Some of these glands are microscopical, and are called cryptae; others are to be found from that size to a line in diameter, and flattened. They are either alone or in clusters. The former {GlandulcB Solitarice, Brunneri^) are found principally about the

* Muller, loc. cit., pp. 287, 288.

t Soemmering, de Corp. Hum. Fabrica.

INTESTINAL CANAL. 39

duodenum and the neighbouring portion of the small intestine, but also exist all the way down in a scattered manner. The latter (GlanduIcB AgminatcBj Peyerij) exist principally in the lower part of the small intestine, and are collected into clusters varying from a few lines to three or four inches in length, but seldom more than from eight to twelve lines broad. They are, for the most part, in elliptical patches, which, in a healthy state, may be recognised rather by a slight discoloration, than by the more ordinary means, and are generally situated some distance from the mesentery. There are about thirty of these clusters, of all sizes, in the ileum, and they are placed nearer and nearer to one another, in approach- ing the ileo-colic junction. All of these muciparous glands are too much flattened to project sensibly into the cavity of the intestine, and, when they do, there is reason to believe that they are in a diseased state, at least in the adult. For the most part, in children, the glands of Brunner may be seen in the whole length of the small intestine.

The mucous coat of the small intestine is every where extremely vascular.

The Small Intestine, though an uninterrupted tube from one end to the other, is divided by anatomists into Duodenum, Jejunum, and Ileum. There is some reason for the first name, but the two latter may be very conveniently blended, as has been done by some, under the term Mesenteric Portion of the intestinal canal.

The Duodenum, named from its being about twelve inches, or twelve fingers' breadth in length, is nearest to the stomach, and is the commencement of the canal. It is sensibly larger than either of the others, and is, moreover, susceptible of great dilatation, whence it has also been called Ventriculus Succenturiatus. Its direction is much varied : beginning at the pylorus, it first of all passes upwards and to the right side till it reaches the neck of the gall-bladder ; it then turns downwards, so as to form a right angle with itself, and descends in front of the right kidney to the third lumbar vertebra, being there placed behind the superior lamina of the transverse mesocolon. It then forms a round elbow, crosses the spine obliquely, under the junction of the mesentery and meso- colon, in ascending from right to left ; and making its appearance

40 OEGANS OF DIGESTION.

to the left of the second lumbar vertebra, is there continued into the mesenteric portion of intestine.

The beginning of the duodenum is moveable, and has a peritoneal coat continued from the lesser omentum ; the descending and the transverse portions have no proper peritoneal coat, but are only loosely fixed between the laminse of the mesocolon ; the termina- tion of the duodenum is both moveable and has a peritoneal cover- ing, from being at the commencement of the mesentery.

From the course assigned to the duodenum, it is evident that it forms the segment of a circle, the concavity of which looks to the left side. This concavity is occupied by the head of the pancreas. The transverse portion crosses the spine below the pancreas, and is separated from it by the superior mesenteric artery and by the venaportarum : behind it are the crura of the diaphragm, the ascending cava, and the aorta.

The organization of the duodenum is the same with that of other portions of the intestinum tenue. Its peculiarities consist only in a partial deficiency of peritoneal coat, and in its augmented size. Its internal or mucous coat is very much tinged with bile, abounds in valvula) conniventes, and about four inches from the pylorus is marked by a small tubercle or elevation, indicative of the orifice of the biliary and of the pancreatic duct. The Glands of Brunner are very conspicuous in this intestine, and are so nu- merous near the pyloric orifice, as to form with some a perfect layer, and to give it a granulated appearance for two inches or more. These glands are considered by Mr. Cruveilhier and Boehm to be pancreatic in their structure.

The Jejunum and Ileum form the remaining length of the small intestine, and have no external marks of difl^erence from each other. They are strung along the mesentery, and, in consequence of their great length, are thrown into folds or convolutions, which give to them a complicated appearance. There is, however, no difficulty in tracing them regularly from one end to the other. They occupy the umbilical, the hypogastric, and a part of the iliac regions, and are surrounded by the circuit of the colon. The upper two-fifths is the jejunum, and the lower three-fifths, the ileum* This distinction, originally introduced by Galen,* from a supposi- tion that the jejunum was more frequently found empty than any

* Portal, Anat. Med.

INTESTINAL CANAL. 41

Other intestine, has no rigid anatonnical support. The only diffe- rence between the two is, that the valvuloe conniventes, existing as they do in the whole length of the jejunum, become less abun- dant at the upper part of the ileum, and finally disappear entirely towards its lower extremity. They decrease indeed very sensibly at the lower part of the jejunum, and sometimes there are none at all in the ileum. In an observation made carefully on this matter by detaching the intestine from the mesentery — inverting it and then measuring, I found the valvulae conniventes to cease as near as may be, in the middle of the length of the mesenteric por- tion of the intestinal canal. The above distinction into jejunum and ileum has. been rejected by the most approved modern autho- rities, such as Haller, Soemmering, and Meckel.

It sometimes happens, that the intestinum tenue has one or more bhnd pouches appended to its sides and opening into its cavity.

The small intestine is supplied with blood from the superior mesenteric artery. Its nerves come from the sympathetic.

The Mesentery (Mesenterium) is a process of peritoneum which serves, as mentioned, to connect the intestinum tenue to the poste- rior parietes of the abdomen, and extends its connexions from the ■left side of the second lumbar vertebra to the right iliac fossa. This attachment, called the root, is about six inches in length; whereas, its lower circumference, which encloses the small intes- tine by giving it a peritoneal coat, is, of course, the whole length of the bowel, (duodenum excepted,) and, consequently, from twen- ty-three to twenty-seven feet in length. This expansion becomes intelligible the moment that the arrangement of the part is in- spected, and is somewhat after the manner of a ruffle, except that It is not puckered at the root.

The two laminae of peritoneum which form the mesentery, con- tain between them the superior mesenteric artery, and the corre- sponding portion of the superior mesenteric vein ; an abundance of lymphatic or lacteal glands and vessels; ramifications from the solar plexus of the sympathetic nerves; and a considerable quan- tity of cellular and of adipose tissue. The superior lamina is con- tinued directly into the mesocolon, and at the place of junction the transverse part of the duodenum is very perceptible beneath. The lower lamina descends along the posterior parietes of the abdonien, concealing the large blood vessels there, and the ureters.

Vol. II.-5

42 ORGANS OF DIGESTION.

Oftke Large Intestine.

The Large Intestine (Iniestinum Crassum) receives the effete nnatter from the small, and is supposed also to make some peculiar secretion of fcecal matter from its internal surface. It exceeds much in its diameter the small intestine, and differs also from it in not being by any means so exactly cylindrical. It commences at the inferior end of the small intestine, and terminates at the anus, describing in this course, as mentioned, a circle which sur- rounds two-thirds of the abdomen, and embraces the intestinum tenue. Like the latter, though only a continuous tube, it is divided into three parts; the commencement of it, which is below the in- sertion of the ileum, and about two inches in length, is the Coecum, or Caput Coli ; the remaining portion, which occupies almost its whole length, is called the Colon, until it reaches the pelvis, when the name is converted into Rectum.

The Mesocolon is a reflection or duplication of peritoneum, that fixes the large intestine to the posterior parietes of the abdomen. This duplicature is not of a breadth so uniform as the mesentery, but allows to the middle of the large intestine very considerable motion, up and down, according to the distention of the stomach, while the lateral portions are very much confined. For instance, in the right iliac fossa the mesocolon is so short that the posterior surface of the gut is in contact with the iliac fascia, and adheres to it by loose cellular substance ; and in the right and left lumbar regions the bowel is immoveably fixed in front of the kidneys near their outer margin : but in the space between these two points, that is to say, where the bowel traverses the hypochondriac and the epigastric or umbilical region, the peritoneal attachment, here called, from its situation, the transverse mesocolon, is so long and so loose that it forms a complete and moveable septum between the small intestine and the stomach. In the left iliac region, again, the large intestine, after having been bound down to the left lum- bar^ is suddenly loosened by an increased breadth of the mesocolon, which permits it to form a large convolution, called its sigmoid flexure. The mesocolon is then continued into the pelvis in front of the sacrum, first of all a little to the left of the middle line of the latter, and, as it descends, it gets directly in front of the middle

INTESTINAL CANAL. 43

line. The portion of it in the pelvis is called mesorectum, from the gut which it serves to attach.

The composition of the mesocolon is precisely the same with that of the mesentery, though it be not so thick: it, therefore, con- sists in two laminae of peritoneum, which contain between them some adipose and cellular matter, along with the arteries, the veins, the nerves, and the absorbent vessels and glands belonging to the large intestine.

When the large intestine is inflated, it is rendered very obvious that it decreases in size from its commencement to the lower part of the sigmoid flexure, it then increases again in size just above ihe anus. Its surface is arranged into three series or lon;:itudinal rows of projections, separated by transverse depressions, the whole corresponding with an internal cellular arrangement, by the latter surface being the reverse of the former.

Its coats, like the small intestine, are four in number; the peri- toneal, the muscular, the cellular, and the mucous.

The Peritoneal Coat prevails in its whole extent, with the ex- ception of the lower part of the rectum: on the ascending and the descending portions of the colon, however, where the latter comes in contact with the parietes of the abdomen, the peritoneum does not invest it entirely; but the transverse portion or the arch, as it is called, and the sigmoid flexure, are completely surrounded.

The surface of this intestine is studded with small projections of various lengths, called Appendices Epiploicse, which are small duplicatures of the peritoneal coat containing fat.

The Muscular Coat is thin, and like that of the small intestine, consists of two orders of fibres, the longitudinal, and the transverse or circular.

The longitudinal fibres have the peculiarity of being collected into three equidistant, flattened fasciculi or bands, of about half an inch in breadth, which begin by a common point at the extremity of the ccecum, and extend to the upper end of the rectum. One of them is along the line of junction with the mesocolon, another anterior, and the third inferior. These fibres, being shorter than he other coats of the gut, have the effect of puckering them into the internal cellular condition alluded to; for, when ihev are cut

44 ORGANS OF DIGESTION.

through, the intestine is much elongated, and its cells disappear. It occasionally happens that the longitudinal fibres, instead of being confined to the bands mentioned, exist in considerable quan- tity over the intermediate spaces; in this case the cellular arrange- ment is not so complete, and in some instances is entirely dispensed with; of the latter, an example is in the Anatomical Museum.

The circular muscular fibres form a thin semi-transparent lamina beneath the last, and do not present any peculiarity of interest, they make a thicker layer than exists in the small intestine.

The Cellular Coat, or Tunica Propria, is a thin lamina of dense cellular substance, serving to connect the muscular with the mu- cous coat, and to conduct the blood vessels and nerves to their terminations on the latter.

The Mucous Coat lines smoothly the internal face of the cellu- lar, and has no doublings or folds, exclusively in it, like the valvulse conniventes of the small intestine.* The transverse projections which it makes between the longitudinal bands, into the cavity of the gut, and which separate the cells of the large intestine from each other, are not mere duplicatures of it alone, but are also con- stituted by the other coats.

Near its commencement this coat has the fungous ay^pearance of the stomach, but about the sigmoid flexure it has a plain, smooth, and, to a degree, a polished surface. It has but few villi, such as exist in the small intestine; indeed, some anatomists deny that it has any, and I have not myself seen them after repeated and care- ful examinations. Its muciparous glands and follicles are nume- rous, and the former, when somewhat enlarged, project; they are very conspicuous about the sigmoid flexure, and in the rectum. Its lacteals are not abundant.

The mucous coat of the large intestine is very vascular, but not so much so as that of the small intestine.

Each division of the large intestine has some peculiarities of structure and connexions; which may now be attended to.

The Ccecum, or Caput Coli, is generally from an inch and a half to two inches long, has a rounded termination below and

* This may be considered as the general rule : if the gut be examined, however, in its whole length, here and there narrow folds may be found in some subjects.

INTESTINAL CANAL. 46

somewhat to the left, from which proceeds an intestinal process, the AppendicLila Vermiformis. The latter is from three to four inches long, is cyhndrical, has a diameter of two or three hnes, and consists of the same number of coats, having the same struc- ture with other portions of the intestinal canal ; its base is the place from which the three longitudinal bands start. It is attached to a narrow duplicature of peritoneum, a process of the mesentery, which permits it to float loosely in the abdomen. It seldom con- tains faeces, but is kept distended by flatus.

The ccecum, as mentioned, is, for the most part, confined to the right iliac fossa, but we very frequently see it with a length of peritoneal attachment permitting it to descend for a short distance into the lesser pelvis.

The Ileo-colic Valve {Valvula Bauhini) is formed at the junc- tion of the ileum with the caput coli. This valve, destined ta prevent the return of faecal matter from the large into the small intestine, consists in a transverse elliptical opening, or slit, whose two lips become approximated in the distentions of the colon. The ileum runs into the left wall of the large intestine, and continues its cellular and mucous coats into the corresponding coats of the latter. The circular muscular fibres of the large intestine separate to a certain degree to permit this introduction, but their farther separation is restrained at each commissure or corner of the lips, by a blending of the structure, aided by a few ligamentous fibres, designated as the retinacula of Bauhin or of Morgagni ; which, hovv'ever, are frequently not very distinct. This separation is also restrained by the two longitudinal bands between which the lips are placed, one of which bands is at the posterior commissure, and the other only a short distance from the anterior. The lips themselves, formed principally by the mucous membrane, approach one another after the manner of the ship dock 6t canal gate ; the superior is somewhat broader than the inferior. Their power, as well as their existence, depends entirely on the tension which is kept up by the natural connexions of the parts; for a very slight dissection causes them to become almost efljaced, and instead of forming an elliptical transverse opening, to be converted into a round patulous one.

The Colon, properly speaking, has some regional distinctions

5*

46 ORGANS OF DIGESTION.

which are serviceable to accurate description. The right lumbar colon, which is bordered in front by the small intestine, and behind, by the right kidney, extends from the ileo-colic valve, to the mar- gin of the false ribs of the corresponding side. The transverse colon, bordered above by the stomach, and below by the small in- testine, goes from one hypochondriac region to the other. It is generally found more distended than the other portions. The left lumbar colon descends from the hypochondriac region of the left side to the sigmoid flexure, being bordered behind and to its right margin by the left kidney, and in front by the small intestine. The sigmoid flexure, placed in the left iliac fossa, forms a convolution, but is very indifferently described by the term applied to it. It is oc,casionalIy very long and loose, and terminates at the left sacro- iliac symphysis. It is not unfrequently found destitute of the par- titions which prevail in other parts.

The Rectum begins at the left sacro-iliac symphysis, and passes obhquely downwards to the centre of the sacrum, thence in front of the middle line of the sacrum, and of the coccyx, to terminate at the point of the latter. It is not regularly cylindrical, but, just above the anus, is dilated into a wide pouch, flattened from before backwards by the pressure of the bladder, and very distinguishable upon the introduction of the finger, for it is but seldom in a con- tracted state. It, of course, has a flexure by adopting itself to the concavity of the sacrum, and is bounded in front by the bladder, the prostate gland and the vesiculas seminales of the male; and by the vagina and the uterus of the fem.ale.

The peritoneum covers only the superior two-thirds of the rec- tum, and attaches it by the short duplicature, called the meso- rectum, to the front of the sacrum. A small pouch, passing down between the vesiculse seminales almost to the base of the prostate, is formed, as mentioned previously, by the peritoneum in its course from the rectum to the bladder.

The muscular coat of the rectum has a thickness and redness surpassing much that of any other intestine, and is divided very clearly into two laminas, the external of which consists in longitu- dinal and, the internal in circular fibres. The external forms in itself a complete coat continuous with the longitudinal bands of the colon, but is much increased in thickness over them by additional fibres. The circular fibres also form a complete coat, and, just

INTESTINAL CANAL. 47

below the pouch of the rectum, are multiplied so much for eight or ten lines as to be a perfect internal sphincter muscle, bearing a strong analogy with the pyloric muscle of the stomach.* At the anus, an arrangement of the muscular coat prevails, which, is not sufficiently attended to by anatomists. The longUudinal fibres, having got to the lower margin of the internal sphincter, turn under this margin between it and the external sphincter, and then ascend upwards for an inch or two in contact with the mucous coat, or rather its cellular substratum, into which they are finally inserted by fasciculi which form the base of the columns of the rectum ; many of the fibres, however, terminate also between the fasciculi of the circular fibres. This connexion must have obviously much influ- ence in the protrusions of the mucous coat, which take place in hemorrhoids and in prolapsus ani.

The mucous coat of the rectum is thick, red, and fungous, and abounds in mucous lacunae and glands. It is smoothly laid above, but below it is thrown into superficial longitudinal folds called columns. At the lower ends of the wrinkles, between the columns, are small pouches of from two to four lines in depth, the orifices of which point upwards ; they are occasionally the seat of disease, and produce, when enlarged, a painful itching. An original ob- servation of Dr. Physick, on the nature of this aflfeclion, and the remedy for which consists in slitting them open or removing them^ induced mc to look for the ordinary natural structure, which I have found .to be as now described.f The radiated wrinkling of the anus is from the influence of the external sphincter ani muscle^ In some subjects, large cells are formed in the cavity of the rec- tum by transverse doublings of the mucous coat only, resembling

* It has been recently asserted that there is also a sphincter niuscle four inches above the anus, half an inch wide in front, and one inch wide behind, from whence accordinjr to Mr. Velpeau the fibres go in crossing one another to fix themselves to the front of the sacrum. Mr. Lisfranc appears to have first announced it and Mr. Nelaton to have described it. Malgaigne, Anat. Chirurg. vol. 2d, p. 3^3.. Paris, 1838. I doubt very much the uniformity of the distinct existence of such a mus- cle, not having been able to find it iti the dissections which I have instituted for the purpose, unless a portion of the ordinary circular fibres should have been selectedi for that designation, in which case several others may be said also to exist.

+ See an interesting paper on Fistula in ano, by M. Ribes, in Mem. de la Society D'Emulation, vol. 9, 1826; where the influence of this structure is alluded to.— It appears that Glisson and Ruysch first described them as valves. Also, an elaborate and excellent article by Dr. Reynell Coates, in tiic Cyclopaedia of Pract. Med. and Surgery, Philada. 1835, under the term anus.

48 ORGANS OF DIGESTION.

the valvulae conniventes of the small intestine; this, however, is not the most frequent arrangement, though deserving of notice. It takes place under the following mechanism.

About a finger's length from the anus there is a puckering of the gut, or deep wrinkling, such as occurs in the colon, and it arises from a similar cause, that is, an abbreviation of the longitu- dinal layer of fibres of the gut : this abbreviation is not wholly cir- cular, but occupies the semi-circumference of the gut on one side, and then a little higher up, the semi-circumference of the other side. This shortening of the gut brings the fasciculi of its circular muscular fibres more together, and, therefore, accumulates them into a greater thickness. At a corresponding part on each side of the gut in its interior, exists a transverse doubling of the mucous coat forming the valvula connivens alluded to. The result of this arrangement is a semi-circular valve on each side, one above the other, the margins, or diameters of which pass each other in the empty and contracted state of the rectum, but touching at the same time, and they present an additional barrier to the involun- tary evacuation of faeces.*

Most subjects, however, have the mucous coat without these valves, and merely in superficial wrinkles of various directions.

The large intestine is supplied with blood from a part- of the superior mesenteric artery, from the whole of the inferior mesen- teric, and from the internal pudic. Its veins empty into the vena portarum. Its nerves are derived from the solar and the hypo- gastric plexus of the sympathetic.

SECT. III. — ON THE MINUTE ANATOMY OF THE MUCOUS COAT OF THE ALIMENTARY CANAL.

In the preceding account of the mucous coat of the stomach and bowels, I have admitted the most generally received opinions,

* It has latterly been advanced by Mr. O'Beirne, that in a natural state the rec- tum is empty, and that the accumulation of faeces preparatory to a stool occurs in the sigmoid flexure of the colon, where they are retained by a contraction of the upper end of the rectum. The principal ground of this opinion is, that foecal matter is rarely met with in the rectum. The observation is so contradictory to my expe- rience in the dissecting room and on patients, that I cannot but reject, it, though it appears to be obtaining some currency, or at least is quoted respectfully. Journal Hebd. 1833, vol. xiii. p. 126. Malgaigne, Anat. Chir. vol. 2d, 341.

/

V y-f

ANATOMY OF THE MUCOUS c6aT. — 49^

as it is in every way proper for medical men to' he a^^are of them. Having been, however, much occupied, a few years a^, in-a*car-' taining the pathology of Asiatic cholera* by dissections, the obser- vations which I then made upon the healthy and diseased structure, have induced me to modify very much my former views, as will be seen in the following pages.

The mucous coat of the alimentary canal, in a healthy state, and successfully injected, appears to consist almost entirely of a cribriform intertexture of veins. These veins being commonly empty at death present themselves then as a soft spongy structure, which gives rise to the ordinary description of its sensible condi- tion as a velvety layer. The most minute injection of the arteries scarcely makes itself visible among these veins, when they are pro- perly injected also; a straggling branch only here and there exhi- biting itself. The arborescence of the arteries is confined to a level beneath the venous intertexture, and is there developed to an extreme degree of minuteness, being intermixed with correspond- ing venous ramuscles, generally larger and more numerous than the arteries themselves. This arrangement seems to occur in that surface of the cellular coat, which makes the base or ground of the mucous. The fine venous trunks of this deeper layer have their originating extremities directed vertically towards the cavity of the gut, and by that means receive the blood of the first venous intertexture or layer, as the petrous sinuses join the cavernous, or the veins of the penis arise from its spongy structure. The meshes of the first venous intertexture are exceedingly minute, and vary in a characteristic manner in the stomach, small intestine and large. This intertexture is very different in its looks from a com- mon vascular anastomosis, and produces in the colon an appear- ance resembling a plate of metal pierced with round holes closely bordering upon each other; these holes constitute, in fact, the fol- licles of Lieberkuhn, so called from their discoverer ;t these folli- cles are gaping orifices, the edges of which are rounded off, and their depth is that of the thickness of the venous anastomosis ; being bounded below by the arterio-venous layer, just alluded to, and by the cellular coat of the part. Nothing short of an entirely success- ful injection will exhibit this venous anastomosis as described; and it may be seen either by injecting a vein, or an artery provided

* Amer. Journ. Med. Sciences, Vol. xvi. May, 1835. t De fabrica et actione Villor. intest. ten. Leid., 1745.

ORGANS OF DIGESTION.

'from the arteries, into the veins, but the latter desirable, because we lose the benefit of a dis- tinction of colour between the two sets of vessels."*^

Ordinary modes of examination give no evidence of the existence in the alimentary canal, from the cardiac orifice of the stomach to near the anus, of an epidermis or epithelium ; on the contrary, they rather lead to a belief of its being absent, in consequence of the softness, tenuity, and transparency of 'the mucous membrane; but that it is really present, may be proved by the following process: — Tear oflfthe peritoneal coat from a piece of small intestine — invert the part and inflate it to an emphysematous condition; the epithe- lium will then be raised as a very thin pellicle, and may be dried in that state ; but as this pellicle retains the air, we hence infer that it lines the follicles, and is uninterrupted by any perforations. This epithelium, if the part be previously injected perfectly, shows dots of injecting matter like those left in the rete mucosum upon a mi- nute injection of the skin, but no arborescence if it be raised up from the veins by the inflation stated. In so doing the villi disap- pear, are in fact unfolded.

In addition to the above proof, the microscope in the hands of numerous modern observers now shows, according to the original opinion of Lieberkuhn, the existence of an epithelium over the whole alimentary canal, and which is formed of minute soft scales.

The villi cannot be seen to any advantage except they be erected by an injection, in which case those of the upper part of the small intestine are found to run into each other very much like the con- volutions of the cerebrum, and to press upon each other's sides in the same way. Some of them, however, are merely semi-oval plates, the transverse diameter of which exceeds the length or ele- vation. At the lower end of the small intestine they become sim- ply conical projections, somewhat curved, with the edges bent in or concave, and they retain this mechanism until they entirely dis- appear near the ileo-colic valve. In the whole length of intestine

* The observations more recently of Dr. Gaddi of Modena, have resulted in wit- nessing a similar indisposition of the arteries to ramify in the mucous coat, and the almost exclusive prevalence of the venous vessels there. He has some views besides of a peculiar nature, such as that the extremities of the veins begin by open mouths on the cavity of the intestine, then unite to form a hollow sphere situated in the submucous tissue, and that the terminating ends of the arteries discharge into these spheres or vesicles. Brit. «& For. Med. Rev. Oct., 1841, p. 530.

ANATOMY OF THE MUCOUS COAT. 51

there is, however, every variety of shape of villi, from oblong curved and serpentine ridges, to the laterally flattened cone standing on its base; the first condition changing gradually to the last in the de- scent of the bowel. Conformably to this definition of villi, none exist either in the stomach or colon, for there we have only the venous mesh. The villi of the jejunum are about the thirtieth of an inch high, and those of the ileum about one-sixtieth.

In the ileum, the superficial venous layer has great regularity and the conical villi stand out beautifully from its anastomoses, or in equivalent language, from the divisions of the follicles. In the upper part of the small intestine the follicles are in equal number to what they are in the ileum ; the regularity of their arrangements being interrupted by the long serpentine and oval villi; but inva- riably the same venous intertexlure exists and forms, in both parts, the chief bulk of the villi, by passing into them. •

In the stomach the follicles vary much in size, and there is an arrangement whereby many of the smaller ones are seen to open into the larger: on an average about two hundred and twenty-five are found upon every square of one eighth of an inch, which would give of course to an inch square sixty-four times that amount, or fourteen thousand four hundred follicles. Conceding the whole stomach to present an area of ninety inches, which is probably below the mark when this organ is moderately distended, as exhi- bited in the preparation upon which this calculation is founded, the entire number of follicles is one million two hundred and nine- ty-six thousand.

The great uniformity of size of these follicles in the colon, and its even surface, enable us to count them with more certainty, and they appear to exist at the beginning of this gut at the rate of about four hundred for every eighth of an inch square, but in the sigmoid flexure at the rate of about two hundred to the same area; they become, in fact, both smaller and less numerous in descend- ing towards the anus. Their average may be stated, therefore, as three hundred for every one-eighth of an inch square — and as nine- teen thousand two hundred for every inch square. Admitting the entire area of the colon to be five hundred inches, and nineteen thousand two hundred of these follicles, to exist on every inch square, the aggregate number will be nine millions six hundred and twenty thousand.

In the colon the resemblance is almost exact with what is called

52 ORGANS OF DIGESTION.

the perforated card or Bristol board, used by ladies for working embroidery or variegated needle-work.

Again, estimating the whole area of the mucous coat of the small intestine at fourteen hundred and forty inches, and allowing for interruptions occasioned by villi; about three hundred and ninety follicles exist upon every one-eighth of an inch square, or 24,960 upon an inch: say then, that about twenty-five thousand follicles are found upon every square inch, and the two numbers multiplied, produce thirty-six millions.

The entire number of follicles in the whole alimentary canal, is, by the preceding Q?,\\m^Xes, forty-six millions nine hundred thou- sand, and upwards. I am very far from pretending to have counted them all, but have made an approximation to the actual number by observing sections of different portions of the same sub- ject, and verifying the observations upon other subjects.

The external surface of the cutis vera presents, as it were, in outHne, the same follicular arrangement; the venous reticular inter- texture appearing broader, not quite so perfect, and more shallow, and forming the papillae ; but as additional experiments are want- ing, it may be passed over with this transient notice; perhaps, indeed, a more skilful hand in adopting the hint may perfect the details.*

In the stomach, the largest of these follicles is about one-ninety- eighth of an inch in diameter, and the smallest about one-four hun- dred and ninetieth. In the colon the largest is about one-two hun- dred and forty-fifth of an inch in diameter, and the smallest about one-four hundred and ninetieth. In the small intestines their size varies in about the same ratio as in the colon, but they are much more irregular in shape, being scattered more in groups, in conse- quence of the villi intervening : some of them penetrate obliquely towards the foundations of the villi ; hence, when examined from the exterior, their distribution is more regular, and they are seen lodged in the cellular coat of the gut.

I have endeavoured to keep the estimate of the number of folli- cles below what other calculators would make it upon an observa- tion of my preparations, and a fair measurement of the area of the alimentary canal, lest the number may seem excessive and incre-

• It is probably this which constitutes the bloody pimples (bourgeons sanguins) of the skin.

ANATOMY OF THE MUCOUS COAT. 53

dible; I have, therefore, the most reasonable assurance of being within bounds on that point. I may now ask their use; is it to secrete or absorb? If they are simply secernents of mucus, the number, one would think, much greater than so limited a secretion requires — moreover, why is it that they become smaller and less numerous towards the lower end of the large intestine, where greater lubrication is required for hardened faeces; in addition, are not the glands of Brunner, (soIUarice,) and of Peyer, {agminatcB,) amply sufficient to furnish the required mucus ? Again, after most sedulous observations upon the villi of all kinds, finely erected by my injections, and placed under most accurate, simple, and com- pound microscopes, I find, invariably, a polished reflecting surface, uninterrupted by foramina, either at their ends or sides, while many of these follicles are found passing obliquely into their bases. An excellent Woollaston's doublet, which makes the villi of ahe ileum appear an inch long, exhibits them with a polished translu- cent surface, without foramina, except where a villus from acci- dent has been broken, a contingency readily recognised by one in the habit of viewing them. Finally, if the lacteal foramina of Lieberkuhn and others, do really exist, why is it that the raising of the intestinal epidermis, by inflation, does not exhibit these fora- mina by the air escaping through them, but, on the contrary, admits of a dried preparation in that state, the villi being com- pletely efTaced.*

Taking into consideration these several objections to the theory of the follicles being secreting orifices, it appears to me that a bet- ter idea of their use is called for, which suggestion is submitted to the profession, with the hope that a more capable person will re- move the difficulty, by additional confirmation of preceding theo- ries, or by the invention of a new one : for my own part, I am much inclined to adopt the opinion of their absorbing faculties. It is generally conceded that the erection and prehension of the Fallopian tube is produced by a vascular turgescence, in which the veins, from their number, must execute an important part; in like manner, as these intestinal follicles are formed in the midst of

* In these and other microscopical observations, I owe much to my young friend, now Demonstrator of Anatomy, Dr. Paul Beck Goddard, who has acquired an ac- curacy and skill in such matters deserving of much confidence.

Vol. II.-6

54 ORGANS OF DIGESTION.

veins, their orifices only become erect and patulous by the disten- tion of those veins, and cannot be well seen by the eye alone, espe- cially in the small intestine, unless an injection has succeeded fully ; but the erection of these veins during digestion puts the follicles in a similar condition ; there is, therefore, some ground of inference, that the act of the Fallopian tube in conveying a germ, and of a follicle in conveying into the thickness of an intestine congenial matter, may be analogous.

The follicles would seem at least not to be essential to the secre- tion of mucus, as it is found where the follicles do not exist, for example, in the frontal, maxillary and sphenoidal sinus, and also in the cavity of the tympanum.

Notwithstanding the facility with which we can detect these follicles, I have failed entirely under various means of examination, in finding any orifices to Peyer's glands, in the dried intestine: they appear to be merely small lenticular excavations* in its sub- stance, and wherever a cluster of them exists, it disturbs the ar- rangement of the villi, and gives to them a scattering unequal dis- tribution. I would also suggest very respectfully to anatomists whether our knowledge in regard to them is sufficiently exact to render farther inquiry useless ? for my own part it appears that this subject requires some additional attention.

The above view, relative to the structure of mucous membrane, presents at least a degree of novelty, by determining, with some precision, the whole number of the G astro-enteric Follicles of the human body, or Follicles of Lieberkuhn, and how they are in every instance formed by meshes of veins^ while the arteries enter only inconsiderably into the composition of the same mucous membrane, to an amount in some measure comparable to the presence of the arteries in other erectile tissues, as the corpus spongiosum and cavernosum penis. In the latter it is familiar to every practised anatomist, that the branches of the arteries are but small, as they terminate in the cells of the penis, which are to be considered as only a modification of the incipient stage of venous trunks. If the corpus spongiosum were in fact spread out into a thin and single

* This observation has been confirmed in Germany by Boehm, who has come to the same conclusion. He says that they contain a white milky and rather thick fluid, with numerous round corpuscles of various sizes, but mostly smaller than blood globules. Am. Journ. Med. Sc. vol. xxi. p. 218.

ANATOMY OF THE MUCOUS COAT.

55

membrane, so as to line a hollow viscus, it would present no very undue representation of what I have denominated the superficial venous layer of the alimentary canal ; it being also admitted that within the circuit of every anastomosis, a follicle was formed.

Viewed on the preparations of the mucous membrane of the small and large intestines which I have, these follicles appear like puncta lachrymalia disseminated by thousands over every inch square, and existing so invariably upon every part, that, as I have stated, the smallest calculation of their numbers puts them at from forty to fifty millions.

It may now be represented, that it is the whole of this vascular and follicular structure, endowed with vital actions the most im- portant to life, and presenting in the aggregate an area of about thirteen square feet, the size of a small breakfast table; whose mor- bid derangements constitute the essential features of Asiatic cholera. It has been shown in some of my dissections, that this apparatus in the progress of cholera is detached entirely from the stomach and colon, in consequence of the excessive actions going on in them. The small intestines also, in some of my preparations, exhibit in patches a similar phenomenon; but as the entire obser- vation has been presented to me in its true light only since the disappearance of the disease, I have had no means of ascertaining the extent to which they suffer in this way.

The anatomy of the muciparous system of the alimentary canal unquestionably requires a more exact attention than has been here- tofore bestowed upon it, especially so as to distinguish between that part which is really glandular, and the foramina or follicles now under consideration. The following extract will explain the difficulty which still exists in regard to a proper conception of the latter.

" The mucous glands, called also follicles or cryptce mucosas, are to the membranes of that name what the sebaceous follicles are to the skin; that is to say, folds of the mucous membrane in form of a cul-de-sac, whose orifices open upon that membrane. These follicles have not yet been discovered over the whole surface of the mucous membrane ; but here, as with the skin, analogy leads us to admit them. It is not long since they have been discovered in the pituitary membrane, where their existence had been denied. Be this as it may, we shall use the same observation upon these

56 ORGANS OF DIGESTION.

glands that was made on the sebaceous, viz. the impossibility of making an exact dissection of the capillary tissues does not allow us to discover all the forms of animal matter; but wherever a particular humour is found in a tissue, we are forced to conclude that this latter is organized in such a manner as to be able to pro- duce it, and when in place of one humour we meet with many, we must acknowledge that the tissue is complex. Such is precisely the case with the mucous membrane of the digestive canal, and especially of the stomach, which could have a form of animal matter calculated to furnish digestive juices, although no gland destined to that purpose is discoverable."* This desideratum of positive evidence, instead of the inductive, is clearly supplied by my preparations.

In infancy, especially, the mucous glands have a sensible thick- ness, which enables us to see them, but the smallest of them require the aid of a microscope, and appear to have been described by Galeati.f As the paper is not to be had in any of the public libra- ries of this city, I can only quote from it on the current authority of anatomical works. In a note fo the anatomy of the human body by Sir Charles Bell, article Intestine, it is stated as follows : — "It has been supposed that the fluids excreted from the surface of the intestines were furnished by very minute foramina, (which are visible by particular preparations,) in the interstices of the villi. See the letter of Malpighi to the Royal Society of London on the pores of the stomach, and the paper by M. Galeati in the Bologna Transactions, on the inner coat, which he calls the cribriform coat. The pores, according to Galeati, are visible through the whole tract of the canal, and particularly in the great intestines." * Meckel designates these as glandular bodies under the name of glandulcB mucosce, cryptcB minimce. Another order of glands are those of Brunner.J They are readily found in the duodenum at all ages; and particularly well in infancy, as low down as the ileo-colic valve. The third order are the glands of Peyer, dis-

* Broussais' Physiology. First American edition, p. 419.

t De cornea ventriculi ct intestinorum tunica. Comm. Bonon., 1745.

X Glandulse inlestini duodeni vel pancreas secundarius; discovered in 1715. See Mangetus, Tiieat. Anal, where this paper is introduced with the plates illustrative of it.

ANATOMY OF THE MUCOUS COAT.

57

covered in 1G77.* The celebrated lluysch appears also to have understood the existence of the follicles of the stomach, and Swammerdam to have had some idea of those of the small intes- lines,t and he calls* them tubuli glandulosi intestinorum interiores. I may here remark, that the figure of the villi of the small intes- tines given by Hedwig, in his Disquisit. Ampullarum, &c. 1797, and which appears, from its introduction into Caldani's and M. Jul. Cloquet's Anatomy, to have a classical value, is, judging from my own preparations, too much a work of the imagination, executed under probably some fallacious views of the part itself: a cluster of cylindrical villi, with holes at the ends, would be an anomaly, for those of the upper part of the intestines are either serpentine folds, as represented in my preparations,, with branches running into contiguous folds; or semi-oval laminae; while those lower down are of a flattened conical shape, somewhat bent, but in every instance they are destitute of what has been termed by Lieberkuhn an ampulla, and to my eye have uniformly polished surfaces, un- interrupted by foramina.

Mascagni has also introduced views of a good kind in regard to the follicular structure of the stomach and colon.J But it is to Sir Everard Home, that we are indebted for one of the best papers on the glandular structure of the stomach of different animals. §

As the real muciparous glands have an orifice leading into each by the admission of anatomists, the follicles described commonly by them, are of this description, and are not comparable in number to the follicles found in the venous meshes. The highest estimate of the number of the former, as made by M. Lelut, fixes them at about forty^wo thousand. || In consulting many of the distinguished modern authorities on this subject, there seems to be scarcely any thing in the anatomy of the intestinal canal which is presented in a more indefinite way; especially in regard to the small intestines, than the difference between the follicles, properly speaking, and the glands ; and none of them, so far as 1 know, have undertaken to approximate the entire number of the follicles and to point out how each one is the centre of a venous anastomosis, is formed by

* Sec also Matiq:etus for the description from Peyer, with his plates. t Mangetus TheaU Anat. Vol. I. p. 310. t Frodr^mo dells grande anatomia. Tab. xiii. § Phil. Trans. 1807 and 1817; and also his Comparative Analomj,. II Bouillaud, Traite du Cholera, p. 25&.

6*

58 ORGANS OF DIGESTION.

it, and always exhibits itself in a collapsed state when the vein is not turgid.*

SECT. IV. — OF THE GENERAL ANATOMY OF THE MUCOUS MEMBRANES.

The extent of the nnucous coat of the alimentary canal, and the important and varied sympathies which it has with most other parts of the body, render useful some remarks on membranes of this kind generally. Mucous Membranes are so called from the nature of the secretion which they furnish : and the term having been first applied to the lining coat of the nose, a similitude of character has caused its extension to that of other organs. The celebrated Bichat, the founder of the science of general anatomy, was the first to adopt fully, and to perceive the value of this classi- fication ; since which it has been almost universally received by anatomists.

As the skin forms an external covering to the body, so mucous membrane lines the internal surface of the hollow viscera. When it is recollected that this membrane forms an internal tegument to the whole alimentary canal, from the mouth to the anus; to all the urinary and genital apparatus ; to the whole respiratory sys- tem, from the nose down the trachea and throughout the lungs; it will be admitted that its extension exceeds much that of the skin.

A mucous membrane presents two surfaces, one of which ad- heres to the contiguous parts,, and the other is free by being inter- nal. The adherent surface is attached by a cellular structure somewhat condensed. This cellular structure is principally re- markable for its want of disposition to secrete fat into its inter- stices; a properly of immense importance, as without it, obstruc-.

* The anatomy of the Gastro-intestinal raucous membrane has elicited several good papers in Europe since 1835, inclusive, the period of my own publication They are rather confirmatory of preceding observations than distinguished by novel- lies, and the venous anastomosis does not seem to be understood or appreciated, except by Dr. Gaddi, of Modena, alluded to in a preceding note. In addition to the authorities already quoted the reader may advantageously consult Boehm de Gland, Intcst. Struct. Penit. Berol, 1835. Boyd on the Structure of the Mucous Mem- brane of the Stomach. Edinburgh, 1836. Likewise Recherches Anatomiques sur la Membrane Muqueuse, &c., par M. Natalis Gaillot in L'Experience^ p. 161. Paris, 1837-8.

GENERAL ANATOMY OF THE MUCOUS MEMBRANES. 59

tions would be continually occurring to ihe destruction of life: it is pervaded by a multitude of fine vessels and nerves, running for- ward to be spent upon the mucous membrane ; and has been unfor- tunately named nervous coat, by anatomists of high authority. The strength of attachment which it furnishes is somewhat varied ; for example, in the small intestinal canal I have often seen the mucous membrane caught at one end and entirely withdrawn from the muscular coat, an experiment which alone can give rigid ideas of its greater length, as by it all the duplicatures or valvules conniventes are stretched out. The experiment succeeds much more certainly by the regular pressure of a column of water be- tween the tunics of the intestine. The mucous membrane of most organs is arranged into wrinkles and duplicatures, for the purpose of augmenting its extent. This arrangement prevails in the nose, and, as mentioned, in the cesophagus, in the stomach and intes- tines; to say nothing of many other instances which are noticed in the description of each organ. In some examples, they are per- manent, and, in others, depend on the slate of contraction of an exterior muscular coat. The interior face of the mucous mem- branes, allowance being made for the inequalities just stated, more- over, presents, when closly viewed, an abundance of more minute depressions and of elevations, causing it to resemble velvet. Some of these depressions are so large as to give it a cellular appear- ance,* as in many parts of the intestinal canal, and in the gall-blad- der, and have been particularly described by Sir Everard Home.

In regard to organization, the mucous membranes are of a soft, spongy consistence; easily yield to mechanical violence; and de- pend for their strength upon the surrounding cellular coat. They are not of a uniform thickness; for example, they are much thinner in the urinary and genital apparatus, than in the alimentary canal; they also present some varieties of consistence. They yield very readily to putrefaction, and are quickly reduced to a pulpy state by the action of the mineral acids. Caustics of all kinds act more promptly on them than on the skin, owing to the protection of the latter by a dry epidermis; Bichat states, that in the practice of the Hotel Dieu, this effect is frequently exemplified, by the administra-

* They are not to be confounded with the follicles, but are a miniature represen- tation of what is called tripe, in culinary language.

60 ORGANS OF DIGESTION.

tion of lunar caustic among the common people for the purpose of poisoning. The nitric acid leaving the silver, quickly applies itself to the mucous membrane of the stomach, and disorganizing it, forms a whitish eschar, which, if life be preserved long enough, is finally detached in a membranous form.

One of the remarkable properties of the mucous surfaces of the stomach and intestines is, that of coagulating milk. According to the experiments of Spallanzani, the gastric juice, in the living state, assists in this change ; but it is perfectly well known in do- mestic affairs, that the dried stomach of a calf, where the juices have been completely evaporated, is also productive of it. The observations of the same author led him to conclude, that the peri- toneal and the muscular tunics of the stomach are insufficient to produce this effect.

The internal surface of the mucous membranes is furnished with small projecting points or spiculae, called papillae or villi. They are particularly conspicuous and numerous, as mentioned, on the upper surface of the tongue and in the small intestine, and bear an analogy of function and organization with the very fine papillae which are seen invariably on the surface of the cutis vera. These papillae are constantly furnished with nervous filaments, giving them a high degree of sensibility; and with an abundance of blood vessels. The term papillae has been more exclusively applied to the projections on the surface of the tongue, from their greater size ; they are there also more distinctly covered with an epidermis, frequently called epithelium, or periglottis. The villi, from their connexion with the process of digestion, have been emphatically denominated the roots of animals. According to M. Beclard,* who has examined them upon a plan of his own contrivance well suited to accurate microscopic observations, they are presented under a diversity of shapes. Those of the pyloric half of the sto- mach, and of the duodenum being broader than they are long, are composed of very small thin laminae, having a tufted arrangement. Those of the jejunum are long and narrow, having more the form commonly assigned to them, while in the lower part of the ileum and in the colon they again become laminated.

It should be observed that notwithstanding the assertion of

* Anat. Gen. p. 253. These notions are not, however, in unison with my own, as just stated. Sect. III.

GENERAL ANATOMY OF THE MUCOUS MEMBRANES. 61

Lewenhoeck, Hewson, Hunter, and others, the fact is still called in question, by many of the most distinguished anatomists of the present time, MM. Beclard, J. F. Meckel, Rudolphi, Miiller, &c., whether the orifices of the lacteals are, under any circumstances, visible on the surface of the villi. Admitting that they do not open as stated, the power of interstitial absorption in the mucous membrane will still account for the chyle finally getting into the lacteals, as well as for fluids passing into the circulation from the stomach, when its continuity with the intestinal canal has been interrupted.*

The Epidermis or Epithelium of mucous membranes is very distinct at their external orifices, but becomes less and less appa- rent towards the interior of the body, until it finally cannot be dis- tinguished by the eye alone; and anatomists of a former period generally considered that it is entirely deficient, notwithstanding the assertion of Haller to the contrary. It is a matter of common ob- servation, that when the interior of mucous membranes is exposed by an eversion for a long time, to the action of the atmosphere; they take on more of the structure of skin, and become evidently covered with a cuticle which protects them and diminishes their secretion. This is exemplified in eversion of the vagina from pro- lapsed uterus, in elongated and tumid labia interna, and in other ways : restore the parts to their natural situation, and they are brought back to their original structure. In the partial prolapse of the mucous membrane of the rectum, from piles, corresponding circumstances occur. From this we infer, that the full deve- lopment of cuticle depends very much upon the degree of exposure which any surface of the body has to undergo. The reverse also lakes place : shut up or close any surface of the skin so that it is put in the condition of an interior cavity, and it immediately begins to assimilate itself to a mucous membrane. This is proved by the tendency in young children to a detachment of the cuticle, or ex- coriation of the opposed surfaces of the deep wrinkles about their thighs and in their perineum ; a tendency obviated by the' practice of nurses of covering these surfaces with powdered starch. It is also manifested frequently in the dressing of wounds with sticking

• Should the suggestion of the absorbing powers of the gastro-cnteric follicles which I have proposed in Section third, be correct, it will dispose of the difficulties and opposing opinions alluded to in this paragraph^

62 ORGANS OF DIGESTION.

plaster, where an incautious approximation of the contiguous sur- faces of the skin, not only is followed by excoriation, but even by ulceration; a fact, the importance of which was formerly set in proper relief by Dr. Physick in his surgical lectures, and of which I have seen an example in a case of extirpated female mamma. The state of this question is, in fine, such that I think we may safely admit upon general observation the existence of a very thin epidermis on the alimentary canal, but so pulpy that it cannot be distinguished except by the process alluded to in Section third of this Chapter. There is less difficulty in proving the existence of an epithehum every where else on mucous membranes, but the fact of its universal presence may be considered now, so definitely settled by the recent microscopical observers, as scarcely to admit of discussion.

The mucous membranes vary in colour from a very light pink to a deep red, which is owing to the blood that circulates in them. In cases of suflfocation, they become almost brown from the con- gestion of blood in them, while in fainting they turn white from the desertion of the latter. The vessels after having penetrated the thickness of the membrane, ramify with extreme minuteness on its surface. The veins in an injection invariably predominate over the arteries by their greater size and distensibility. In con- sequence of their superficial situation, the vessels being unsupported on one side, are exposed to rupture from slight concussions; in this way hemorrhage is produced in the lungs from coughing, and bleeding at the nose from blows upon the head.

Exhalent orifices exist in great numbers in the mucous mem- branes ; this is especially the case in the lungs, where the pulmo- nary perspiration, as it is called, is very obvious to common observation. Elsewhere, this discharge is so much blended with the mucus of the part, that it is difficult to appreciate its quantity. From the superficial situation of the blood vessels, it is clear that the exhalent orifices or pores, have but a short course to run. This is considered by Bichat as a satisfactory reason for the ten- dency of the blood to escape through them, or to ooze out where there is no rupture.

Absorbents exist also in great numbers, as proved by the absorp- tion of chyle, of watery drinks from the intestinal canal, and by the inhalation of the vapour of spirits of turpentine into the lungs.

GENERAL ANATOMY OF THE MUCOUS MAMBRANES. 68

rapidly communicating the particular smell of this article to the urine. There are, moreover, cases recorded of obstructed urethra, where the urine has been almost entirely absorbed by the mucous coat of the bladder.

In regard to nerves, the mucous membranes are well furnished with them. Bichat has remarked that wherever these membranes are situated near the surface of the body and enjoy common sen- sibility, they are almost wholly furnished from the central portions of the nervous system, as the brain and spinal marrow: this is ex- emplified in the conjunctiva, the pituitary membrane, the palate, the glans penis, &c. On the contrary, the sympathetic nerve fur- nishes the intestines, the bladder, and the excretory tubes gene- rally.

Mucous Glands, as they are called, exist throughout the system of mucous membranes, being situated either under them or in their thicknesses. From them is derived the mucilaginous fluid which lubricates so abundantly their interior surfaces, so as to facilitate the passage of extraneous bodies, and, at the same time, to protect the membrane from mechanical violence. These glands are of various sizes, from that of the tonsils and the muciparous glands on the lips, cheeks, and root of the tongue, to the almost impercep- tible cryptae of the bladder and urethra. Their shape is either lenticular, rounded, or that of a pouch. The former two have their parietes of a sensible thickness, but the last are too thin to be distinguished from the mucous membrane itself. For the most part, the excretory duct of these glands is short and patulous, so as to lead directly into the substance of the gland. This is re- markably the case with the tonsils, which consist in a congeries of these follicles; and with the glands on the root of the tongue. In some animals they are so numerous as to form almost a distinct lamina to the intestines; after the manner of the human subject, on the palate and parietes of the mouth.

The Mucosity discharged from these glands is cne of the prin- ciples of animals, and, as is well known, exists also to a great extent in some vegetables. When perfectly pure and fluid, it is white, transparent, inodorous, and insipid. It is insoluble in alco- hol, but soluble in acids. Water forms more than nine-tenths of it, the remainder is mucus, properly speaking, blended with some neutral salts of soda and potash.

64 ORGANS OF DIGESTION.

The mucus which covers the surface of the mucous membranes consists chiefly of separated particles of epithelium mixed with a fluid exudation, while the mucous follicles are said to pour out a fluid holding mucous globules suspended.

The mucous membranes are exposed to a multitude of morbid alterations, such as polypus, scirrhus, cancer, phlegmorrhagiae or serous fluxes, blennorrhagiae or mucous fluxes, inflammation in all its forms, gangrene, ulcerations, and congestions.

CHAPTER V. Of the Assistant Ghylopoetic Viscera.

SECT I. — OF THE LIVER.

The Liver {Hepar, Jecur) secretes the Bile, and is the largest glandular body in the human frame. It, as mentioned, occupies the whole of the right hypochondriac region, the upper half of the epigastric, and, as it becomes thinner in going towards the left side, it occupies a small space in the right superior part of the left hypochondriac region. Its whole superior face is in contact with the diaphragm ; on the left it is bounded by the spleen, and below by the stomach and the transverse colon ; behind it, are the verte- bral column and the ascending cava.

The shape of the liver is like one half of an ovoidal body cut into two in the direction of its long diameter, and having the thick end turned to the right side. It is about ten inches in length by six or seven wide, and weighs from four to five pounds in the adult. Its colour is a reddish brown, generally; though, on its under surface and about its edges, broad blue or black patches are constantly met with, which do not indicate any morbid derange- ment.

Its upper surface is of a uniform convexity, rather more promi- nent at the right posterior part than elsewhere ; adjusts itself accu- rately into the concavity made by the under surface of the dia-

THE LIVER. 65

phragm ; and is unequally divided from before backwards by the suspensory ligament. The anterior margin is thin, and is notched where the suspensory ligament begins ; the posterior margin is much thicker, and has near its middle a broad depression, to fit it to the pro- jection of the vertebral column. The ascending vena cava forms a superficial sulcus upon this margin, and frequently there is a com- plete canal through the substance of the liver for transmitting it. The right extremity is very thick, and almost fills the hypochon- driac region of that side, while the left extremity is reduced to a thin, tapering, and flexible edge.

The under surface of the liver is much more irregular than the upper; it is traversed in an antero-posterior direction, in a line corresponding with the attachment above of the suspensory liga- ment, by the umbilical fissure, {Sulcus Umhilicalis) which extends from the notch in the front edge to the depression behind, and ob- tains its name from having accommodated in the foetal state, the umbilical vein, now converted into a round ligamentous cord. In the posterior part of this fissure is likewise to be seen, in the same condition, what remains of the ductus venosus. The anterior por- tion of the umbilical fissure is not unfrequently converted into a complete canal, by a portion of hepatic substance crossing it like a small bridge. The transverse fissure {Sulcus Transversus, Inter- medius) is situated in the middle of the under surface of the liver, and extends alonsj a third or fourth of the lonor diameter of the latter. It begins somewhat to the left of the umbilical fissure, and crossing it at right angles, proceeds towards the right extremity. It contains the vena portarum, the hepatic artery, and the hepatic duct, lymphatics and nerves ; all of which are bound to each other by a close cellular substance.

The suspensory ligament above, and the umbilical fissure below, give occasion to divide the liver into Lobes, Right and Left; of which the right is by much the largest, and accommodates almost entirely the transverse fissure, having also on its under surface some subordinate elevations, to wit, the Lobulus Spigelii and the Lobulus Quartus, together with the Gall-Bladder.

The Lobulus Spigelii is placed between the transverse fissure and the posterior margin of the liver, to the right of the posterior end of the umbilical fissure. Its shape is somewhat prismatic, bifurcating in front ; one of the elongations or prongs is a papilla overhanging the transverse fissure, and is, therefore, considered as

Vol. II.— 7

06 ORGANS OF DIGESTION.

one side of the gate-way (porta) opened for the vena portarum ; the other elongation is a small ridge, sometinaes called Lobulus Caudatus, and is lost gradually on the under surface of the great lobe, by inclining to the right.

The Lobulus Quartus, or Anonynaus, is not by any means so elevated as the last, but having a flattened surface, is placed in front of the transverse fissure, between the fore end of the umbilical fissure and the gall-bladder; its posterior extremity is the other side of the gate-way (porta) of the Liver, and is just opposite to that furnished by the Lobulus Spigelii.

The liver, from being completely enveloped in peritoneum, has a smooth glossy appearance. The reflections of this membrane, from it to the parietes of the abdomen, form the ligaments, as they are called, which consist each of two laminae. The Falciform Ligament, or Suspensory, containing in its anterior margin the remains of the umbilical vein, now called Ligamentum Teres, begins at the umbilicus, extends from it along the linea alba and the middle line of the diaphragm, and, as mentioned, is reflected to the upper surface of the liver, from the anterior to the posterior margin. The Right Lateral Ligament is situated behind, and de- parts from the back part of the diaphragm to the posterior margin of the right lobe. The Left Lateral Ligament also goes from the back part of the diaphragm, and is attached along the posterior margin of the left lobe. Where the suspensory ligament inclines on each side into the lateral, it passes with so much obliquity as to leave some portion of the posterior margin of the liver unco- vered by peritoneum; the latter, where it describes the periphery of this space, has been rather unnecessarily designated as the Coronary Ligament.

In addition to the peritoneal coat, the liver has another, con- necting it with the peritoneum, and seeming to be only condensed cellular substance, which also penetrates into the substance of the gland, and holds its constituent parts together. It is particularly well seen within the circle of the coronary ligament.

Of the Organization of the Liver.

The glandular substance of the Liver is fragile and easily lace- rated ; and consists of a congeries of spherical or polyhedrical

THE LIVER.

G7

grains, called by Malpighi acini from their resemblance to small berries; they are best seen on tearing the organ, arc united in mass by the elongations of the celluhir coat, and traversed by the trunks of the blood vessels. Each of tiiese granulations is about the size of a millet seed, and is a representative of the entire gland, as its structure is complete in itself; being formed by the terminations of the blood vessels, and by the origin of a branch of the hepatic duct, called the porus biliarius. When examined with a micro- scope, it is said that these acini are observed to be composed of a yellow and of a brown-lookin^? substance; it has not, however, occurred to me to see the distinction in a very satisfactory way, though it is recognised by anatomists of high authority.*

The liver is made extremely vascular by the ramifications of three kinds of blood vessels, the Vena Portarum, the Hepatic Artery, and the Hepatic Veins. The first two convey the blood to it, and the third removes it again, into the general circulation, by emptying into the ascending vena cava. There are also the commencing radicles of the hepatic duct, lymphatic vessels, and the nerves.

The Vena Portarum having arisen from the junction of all the veins of the stomach, intestines, pancreas and spleen, is about three inches in length when it reaches the transverse fissure, by going over the duodenum and under the pancreas. It immediately divides into two branches, called collectively the Sinus Venae Por- tarum, which is at right angles with the trunk of the vein; the right branch being the shortest and largest, is distributed by radia- ting trunks to the right lobe of the liver; the left branch is distri- buted, after the same manner, to the left lobe, to the lobulus spigelii, and to the lobulus quartus. Some of its branches anastomose with the hepatic veins, which accounts for the ease with which an injection will pass from one to the other. Other branches of a smaller description anastomose with the biliary ducts, but with less freedom than in the preceding case: and lastly, the most deli- cate ramifications are spent upon the cortical or yellow matter of the acini, without penetrating to the brown.f

The Hepatic Artery is a branch of the cceliac, and in approach- ing the transverse fissure divides into three or more branches, that penetrate the substance of the liver, between the sinus venae por-

* Bicliat, Meckel, &.c. \ Mappes, J. V, Meckel, loc. cit.

ORGANS OF DIGESTION.

tarum and the ducts as they come out; one branch goes to the right lobe, another to the left, and a third to the lobulus spigelii. There is sonne variety in regard to the precise mode of distribution, and their division into subordinate ramifications frequently occurs before they get fairly into the substance of the liver. When there, they seem to be intended for the nourishment of this organ, accord- ing to the observations of several able anatomists; and follow the ramifications of the vena^^ortarum and of the biliary ducts, form- ing upon them a very delicate and. complicated tissue of anasto- mosing vessels; some of which, probably the vasa vasorum, com- municate with the vena portarum.

The Hepatic Veins arise in the acini from the capiHary termi- nations of the vena portarum and the hepatic , artery. Their branches are successively accumulated into three large trunks, the collective area of which vastly exceeds that of the vessels bringing the blood to the liver. Two of these trunks come from the right lobe and one from the left, to empty into the ascending cava, while it is still in contact with the liver, immediately below the diaphragm,; just below the preceding trunks there are five or six, sometimes more, small hepatic veins, coming from the posterior margin of the liver, and from the lobulus spigelii. I'he hepatic veins are destitute of valves, and remarkable for the thinness of their pa- rietes. An injection passes readily from them into the other systems of vessels. They may be recognised by their insulated course, and by their consisting in trunks which converge^ from the periphery of the liver to the vena cava> while all the other vessels diverge from the transverse fissure to the periphery, and conse- quently cross the course of the hepatic veins.

The commencing radicles or ramifications of the Hepatic Duct, take their origin in the acini: and, as is said, upon the boundary between the two kinds of matter, avoiding the brown and passing through the cortical.* The larger branches converge into their respective trunks successively or in pairs; while the primordial, or most minute ones, converge several of them to the same point, giving a penicillous appearance. These several tubes constitute the Biliary Pores (Fori Biliarii) and are always in the same group with the branches of the Vena Portarum and Hepatic Artery. It is unsettled whether these brush-like or penicillous ends of the pori

* J. F. Meckel, loc. cit.

THE LIVER.

09

biliarii are enlarged at their free extremities so as to be there like a pin at its head in a manner so common in glandular structure. Krause asserts the fact, and states that the enlargement measures from ^^ to -y of an English line, and there are said to be [)rcpara- tions of the kind in Utrecht.* It is asserted that a fine injection passes more readily from them into the lymphatics than into any other order of vessels ; which may account for the promptitude o{ jaundice upon an obstruction of the hepatic duct. The most minute branches of the biliary ducts in the acini are so close together that they seem to be united to one another. Their dia- meter, according to Miiller, varies from ^jy to -^l^ of an English inch; they are, therefore, much larger than the finest capillary blood vessels.

According to the observations of Mr. Kiernan,-|- the acini of anatomists generally should be called lobules, inasmuch as they consist in a collection of smaller granulated bodies, to which he restricts the name of acini. The objection to this principally is, that it introduces a new definition on a point heretofore considered as settled in the universal phraseology of anatomists, but as his descriptions are founded upon this assumption, the latter may be admitted for the time.^ His statement then is that the finer branches of the vena portarum, which he calls Interlobular veins, form a perfect and minute plexus surrounding the lobules or small granu- lar masses of the liver; they then form convergent lines of vessels directed towards the centre of each lobule and communicating by transverse branches with one another. These latter connexions or the sets of veins making them constitute the lobular venous plexus, and in their intervals are placed what he calls the acini or subordinate granules.

In pursuing farther his line of description, we have next to say that the Hepatic Duct forms a plexus upon the lobules like that of the vena portarum; the plexuses of the contiguous lobules being indisposed to anastomose, though he thinks there is ground to be- lieve in such anastomosis. The interlobular biliary ducts then pene- traJe the lobule and ramify by anastomotic connexion through it. The Hepatic Artery makes also a plexus upon the surface of

* Mailer, Phyp., p. 491. London, 1840. t Anat. and Physiol, of Liver, Pl)ii. Trans. London, 1833. 7*

70 ORGANS OF DIGESTION.

the lobule, and penetrates interiorly from its periphery towards the centre. Its ultimate branches supply the meshes of the vena por- tarum ; of the venae hepaticas, and of the biliary ducts, but their final termination is unsettled ; Kiernan believes that it is in the vena portarum ; and Meckel that they end in the incipient branches of the venae hepaticae.

The Hepatic veins, according to Mr. Kiernan, are seen as a small trunk in the centre of a lobule ; this trunk arises from the convergence of from four to eight venules from the periphery to the centre of the lobule. The trunks having escaped each from its respective lobule then unite with contiguous trunks similarly circumstanced, and as the arrangement is progressive by the suc- cessive junction of larger and larger trunks, we have, finally, the large Hepatic veins formed which discharge into the ascending vena cava.

It is stated by Mr. Kiernan, that the elements of the above arrangement of ducts and blood vessels are formed very distinctly, in the left lateral ligament of the liver.

He appears not to have succeeded in injecting the hepatic veins from the hepatic artery, though he can inject them from the vena portarum. His injection was probably not fine enough, as there is not the slightest difficulty in filling all' of the ducts and blood ves- sels of the liver from either set, provided one throws in a very fluid injection. The use of water simply will prove this beyond doubt; and I have made a very complete injection of the lymphatics of the liver when I threw the common size injection coloured with vermilion, into the hepatic arter3\

Miiller considers that there is an ultimate plexus of capillary blood vessels with which the other three communicate freely, this is probably the fact, including the lymphatic system also, but the precise mode of its formation is as yet not ascertained, an idea long ago advanced by Chaussier in regard to all glandular struc- tures.

As an ultimate feature in the microscopical structure of the liver its parenchyma or peculiar final atomic arrangement, according to Wagner, consists in nuchated cells, now ascertained to be a very common feature in the textures generally of the human body.

At the bottom of the transverse fissure of the liver is to be found a dense cellular fibrous tissue, which invests the vena portarum,

THE LIVER.

71

the hepatic artery, and the biliary ducts; and, as they all keep together in their ramifications, this tissue follows them throughout the substance of the liver, and thereby forms sheaths for them. It may be considered as continuous with the processes sent in from the cellular coat; and, contrary to the opinion of Glisson, whose capsule it has been called, it is devoid of muscular structure.

The liver appears in the embryo to be originally formed by a protrusion of the walls of a part of the intestinal canal;* the lungs and pancreas present a similar mode of evolution.

Of the Gall-Bladder.

The Gall-Bladder (Cistis Fellea) is a reservoir, for the bile secreted by the liver. It is fixed on the under surface of the great lobe, to the right of the umbilical fissure, and removed from the latter by the lobulus quartus.J It is an oblong pyriform sac, having its anterior extremity or fundus projecting somewhat beyond the anterior margin of the liver, while the posterior end reaches to the transverse fissure. Its long diameter inclines slightly /to the right side, so that it is not precisely in an antero-posterior line. It- varies in its shape in diflferent subjects, being much more sphe- roidal in some than in others. Its fundus is rounded and obtuse, while the posterior end is gradually reduced to a narrow neck, which is bent up on itself, so as to retard the flow of a fluid through it. Its upper surface is in contact with the substance of the liver, and is received into a broad shallow fossa, while the lower sur- face is projecting, and by coming in contact with the transverse colon, tinges it with bile, by transudation after death.

The Gall-Bladder has three coals, a peritoneal, a cellular, and a mucous one.

The Peritoneal Coat is not complete, but only covers that part of the sac not received into the fossa on the under surface of the liver; it is, therefore, a continuation of the peritoneal coat of the latter; sometimes,, however, the gall-bladder is so loosely attached

» Muller, loc. cit., p. 490.

\ I have seen an instance where it was to the left of the umbilical fissure, on the small lobe. The latter was mucl> longer than common. Dec. 1830.

72 ORGANS OF DIGESTION.

to the liver that it almost hangs off from it, in which case the peri- toneal coat is nearly complete.

The Second coat is condensed cellular membrane,. (Tunica Pro- pria.) Through it ramifies a great number of lymphatics, and blood vessels; below, it attaches the peritoneal to the mucous coal, and above, the latter to the liver.

The Mucous Coat is always tinged of a deep green or yellowy by the bile which it contains percolating after death; for it is said to be, before that, of a light colour. This coat is thrown into irregular tortuous folds or wrinkles of extreme delicacy, in the intervals of which are many round or polyhedrous cells, causing it to look, when floated in water, like a fine honey comb: such as are about the fundus of the sac are superficial, and not so distinct ; but those near its middle and about the neck, are a line or a line and a half deep. In the neck or apex, and in the beginning of the cystic duct, are from three to seven, sometimes twelve, semilunar duplicatures of the internal membrane, which also retard the flux and afflux of any fluid, though they do not afford so much resis- tance to the ingress as to the egress of it. These duplicatures are sometimes partially arranged into a spiral valve, projecting from the inside of the duct, and forming two or three turns.* Very small mucous follicles exist over the internal face of this membrane, the discharge of which fills the gall-bladder when the secretion of bile has been interrupted by diseased action, as in yellow fever, or by scirrhus of the liver.

The artery of the gall-bladder is a branch of the hepatic. Its veins empty into the vena portarum. Its nerves come from the sympathetic, and its lymphatics join those of the liver.

The gall-bladder is developed as a diverticulum from the Hepatic Duct.

Of the Biliary Ducts,

A succession of very fine branches having arisen from the acini of the liver, these branches are united into three or four trunks by the time they reach the transverse fissure. The trunks then co-

* Discovered latterly by M. Amussat, of Paris. M. Amussat has also detected muscular fibres in the gall-bladder and biliary ducts, in which we see an analogy with other hollow viscera. — Am. Jour. Med. Sciences, Vol. ii. p. 193.

THE LIVER. 73

alesce into a single Duct, the Hepatic, of eighteen or twenty lines in length, and about the diameter of a writing-quill. The Hepatic Duct is then joined at a very acute angle with the duct from the gall-bladder, which is somewhat shorter and smaller; the union of the two forms the Common Duct, {Ductus Communis Choledochus.) The latter is larger than either of the others singly, and is three or three and a half inches long; it descends behind the right ex- tremity of the pancreas through its substance, passes nearly an inch, obliquely, between the coats of the duodenum, becoming at the same time diminished in diameter; and, finally, ends by an orifice still more contracted, on the internal face of this gut, on its second turn, and about three or four inches from the stomach. The ori- fice is marked by a small surrounding tubercle somewhat obscured by the valvulse conniventes.

The Hepatic, the Cystic, and the Common Duct are situated, as mentioned, along the right margin of the lesser omentum, and have the vena portarum and the hepatic artery to their left.

The bile ducts are formed by two coats ; the external is a fibrous, lamellated, and very extensible membrane, while the internal is mucous, having the same structure with that of the gall-bladder, of which it is in direct continuation. In the Cystic Duct, and at the lower part of the Common Duct are several longitudinal folds. The Common Duct sometimes receives, just before it empties into the duodenum, the Pancreatic Duct.

Of the Bile,

This secretion from the liver, is of a deep yellow, sometimes green colour: when recent, it is thin and fluid; but after it has been conveyed to the gall-bladder, and permitted to remain there for some time, it becomes as thick as molasses, and increases also in the intensity of its colour and in bitterness. Some anatomists have believed that there was a more direct communication between the liver and the gall-bladder than that through the hepatic and the cystic duct; but repeated and close observations have proved the opinion to be erroneous, or at least destitute of proper proof: it is therefore, clear, that the difference between the hepatic and the cystic bile, depends upon the watery particles being removed from

74 ORGANS OP DIGESTION.

the latter by the absorbing power of the internal coat of the gall- bladder.

According to Berzelius, the chemical analysis of bile furnishes about eighty parts of water, eight of a particular substance which assunnes a resinous condition on the application of an acid : three of nnucus; and nine of saline matters; of which soda is a principal constituent.

SECT. II. — OF THE SPLEEN.

The Spleen {Lien, Spleny is situated deeply in the posterior part of the left hypochondriac region, and is bounded above by the diaphragm, below by the colon, and on the right by the great end of the stomach, and by the pancreas. It is not ascertained that it secretes any thing.

Its colour varies from a deep blue to a dark brown. In shape it resembles the longitudinal section of an oval, being flat or very slightly concave on the surface next to the stomach, and convex on that contiguous to the diaphragm. Occasionally its margins are notched, but this is not invariably the case. Its flat surface is slightly depressed longitudinally in the centre into an imper- fect fissure, where the blood vessels enter it by six or eight foramina.

Several spleens sometimes exist in the same individual, in which case the supernumerary ones are not larger than nutmegs. The common size of this organ is about four and a half inches long, by two and a half or three wide, in which case it has a solid firm feel; but it very often exceeds these dimensions; its transition and va- rieties of magnitude are so frequent, that no settled rule can be established. In it's inordinate enlargements I have seen it only a little smaller than the liver ; its texture in this case is soft and easily lacerated.

It is fixed in its place by three lines of reflection or processes of peritoneum, called ligaments, whose names indicate their places of attachment. They are the Gastro-Splenic Ligament or Omen- tum, which passes from the stomach to the spleen, and in which are the vasa brevia of th^ stomach; the Splenico-Phrfenic Liga- ment, which goes from the spleen to the diaphragm: and the Splenico-Golic Ligament, which passes from the spleen to the

THE SPLEEN. 75

colon. These reflections, by being continued over the spleen, give it a complete peritoneal coat, which is raised up with more difli- culty than the corresponding membrane ot" any other viscus of the abdomen, and is commonly thrown into very small inequalities or wrinkles.

The internal or proper coat of the spleen is a grayish, compact, extensible, and elastic membrane, the use of which is evidently to sustain the natural shape of the organ, and to support its parenchy- matous structure. It sends in processes to accompany the blood vessels, and from its internal face there proceeds a multitude of lamellae and of fibres, which traverse its cavity in every direction, and reduce it into a cellular condition, not unlike the spongy struc- ture of bones.

The spleen, in proportion to its size, is furnished to a remarkable degree with blood. The largest branch of the coeliac artery runs to it along the superior margin of the pancreas, forming numerous serpentine flexures, and distinguished for its thickness ; it divides into several trunks for penetrating into the spleen, and enters by the foramina in the fissure. The veins come out by a number of trunks equal to what the artery is divided into; they assemble then into a single trunk, which attends the artery along the pancreas, and is remarkable for the tenuity and extensibility of its coats. The splenic vein is destitute of valves, and empties into the vena portarum.

The spleen has also lymphatic vessels ; and is furnished with nerves from the solar plexus.

Of the Intimate Structure of the Spleen. — The Splenic artery having penetrated into this organ, is divided and subdivided into a radiating succession of very fine branches, which, according to the injections of Ruysch, do not anastomose with each other; in con- sequence of which, one part is sometimes finely injected and not another, of which, in my own observations, I have had an example. The veins, on the contrary, do anastomose, not only as regards the collateral branches of the same primitive trunk, but also by the collateral branches of diflferent trunks. These anastomoses are not large. The arteries terminate freely in the veins, as may be proved by fine injections, and by the microscope.

The mass of the spleen, upon superficial examination, seems to consist in a dark brown bloody pulp, which is contained in the cells

76 ORGANS OF DIGESTION.

dividing the cavity of the internal coat, and may be easily demon- strated by tearing the spleen, and scraping it with a knife handle. MM. Assolont and Meckel believe, that blood, besides being in the arteries and veins, is placed in a state of particular combina- tion and of intimate union with the other organic elements of this viscus, and with a large quantity of albumen; and that this combi- nation of the blood forms the dark brown pulp alluded to. The great quantity of albumen in the pulp, is readily proved by the hard coagulum which it forms, when steeped in alcohol.

A question has arisen whether the pulp be extravasated in 'the cells which contain it, or whether it be still retained in the extre- mities of the blood vessels. Superficial examination is in favour of the first, but M. Marjolin denies it on the following grounds; that injections, cautiously made, pass immediately from the arte- ries into the veins ; and that the spleen, when successfully in- jected and frozen, does not exhibit ice in the interstices of its ves- sels, while their capillary ramifications distended by the injected fluid, are distinctly seen. From these facts he concludes that the glandular structure of the spleen is formed essentially of arterial and venous capillary vessels with very delicate and extensible coats ; that they communicate with one another without the intermedium of any cell ; and that the extreme tenuity of these vessels, and their extensibility in every direction, are sufficient to explain the aug- mentation of volume of the spleen, under certain circumstances, as well as the promptitude of its diminution under others.

The pulpy substance of the spleen under the microscope, is com- posed of small spheroid or oval granules of a reddish brown colour, and about the size of the globules of the blood. According to Mr. Gulliver,* they are more unequal in size than the blood discs, their diameter varying from 1-1777 to 1.600 of an inch, and they are found in blood taken from the splenic vein. They are easily sepa- rated from one another.

The minute arteries of the spleen ramify in tufts among them and then terminate in a plexus of venous canals whose walls are so thin that the veins appear as mere channels in the pulp.

In addition to this pulp, many observers have met in the spleen with an abundance of rounded corpuscles, varying in size from an almost imperceptible magnitude to a line or more in diameter.f

* Gerber's Genl. Anat. p. 102.

'I" Malpighi, Ruysch, Hewson, Home, Dupuytren, Meckel, &c.

THE SPLEEN.

77

They are of a gelatinous consistence, soft, grayish, and semi-trans- parent, and either cluster together, or arc widely separated. By Malpighi, they were considered glandular, and by lluysch,* as con- voluted vessels. Professor Soemmering, from the following para- frraph, seems to join in the opinion of the latter: "Qui nonnun- quam occurrunt, acini vel glomeruli, microscopii ope accuratissime explorati nihil sunt, nisi vasorum fasciculi, vel teretes penicilh aut cirri vasculosi." According to the ob~servations of Sir Eve- rard Home, they swell considerably after an animal has finished drinking.

The corpuscles are seen with difficulty in the human spleen, in animals they are much more distinct, as in the hog, sheep, and ox. Miillerf admits their connexion with the arteries, but is in- clined to consider them as excrescences from their coats, as in his injections the arteries were seen to pass through, but not to ramify in them. Their exact structure is undetermined.

The spleen, from having no excretory duct, and consequently, from our inability to ascertain whether it secretes, has its nature and uses shrouded in mystery. No single theory concerning it has ever been generally adopted, for speculations have multiplied in proportion to the obscurity of the subject. The idea, however, on the use of this body, which to me is most reasonable, is, that it acts a subsidiary part to the liver. It would seem, indeed, as a general rule in regard to glandular structures and such other highly vascular organs of the body as have an intermittent func- tion, that the blood which is sent to them during their state of activity, should be passed off through a different channel, while they are in a state of repose. This does a double service, it pre- vents superfluous secretions, and it also keeps up the vascular equi- librium of the body, as there must be always in readiness a quan- tity of blood sufficient for the supply of any secretion which may be wanted for the time.

This proposition will derive some additional illustrations from the foetal state. The kidneys being then inactive the capsulaj renales take oft' their blood, and thereby prevent what would other- wise be a very inconvenient secretion of urine; again, the lungs being also then inactive, the circulation through them is propor-

• Epis. Anat. IV. t Physiol, p. 618.

Vol. II.-8

78 ORGANS OF DIGESTION.

tionately reduced, and the superabundant blood is conducted through the thymus gland. But as the full functions of the lungs and of the kidneys are established upon birth, and continue unin- terrupted during life, their supplementary organs, the thymus gland, and the capsulse renales, are not wanted, and they wither away after the early period of infantile existence is passed.

In regard to the hver, its functions also suspended during the foetal state, are of an intermittent kind throughout life, the spleen may, therefore, be considered a vicarious organ for it during the whole period of existence, receiving its blood during the conti- nuation of uterine life, and, in the intermission of action, during common life. The spleen is, therefore, an organ useful to the foetal and to the perfect state, and we, consequently, never see it in the collapsed and dwindled condition of the thymus gland, and renal capsules.

The same reasoning which applies to the spleen, will also apply to the Thyroid Gland: the latter may be considered as exe-, cuting for the salivary glands during foetal and perfect exist- ence, what the spleen does for the liver. For it is ascertained, that the salivary glands are inactive during fcetal existence, have only an intermittent action during perfect life, and, therefore, probably stand in need of a supplementary organ during their pe- riods of inactivity.

SECT. III. — OF THE PANCREAS.

The Pancreas (Pancreas) secretes saliva, and is the largest of the salivary glands. It is fixed in the lower back part of the epi- gastric region ; and extends horizontally across the spine, being separated from it by the lesser muscle of the diaphragm. It is connected to the spleen on the left ; at its right extremity is sur- rounded by the curvature of the duodenum ; is bounded in front by the stomach, which conceals it; and is placed between two laminse of the mesocolon.

The pancreas is about six or seven inches long, two wide, and flattened before and behind. Its figure would be represented by a parallelogram, were it not that its right extremity is en- larged considerably into a head or tuber, to which Winslow gave

THE PANCREAS. 79

the name of the Lesser Pancreas. The anterior face of this organ is turned obliquely upwards, and is covered by the superior lamina of the mesocolon. The posterior face looks obliquely downwards, and is in contact with the aorta, the vena cava ascendens, the superior mesenteric vessels, and several nerves: along the superior margin of this face exists a long superficial fossa, occupied by the splenic artery and vein.

With ihe exception of the loose covering given by the meso- colon, the pancreas has no peritoneal coat; neither has it an ap- propriate tunic, unless we consider as such the lamina of con- densed cellular membrane which envelops it, and sends in processes between its lobules, as in the case of the salivary glands in the neck. .

Of ihe Minute Structure of the Pancreas. — This body, like the other glands, which discharge saliva, is of a light gray or pink colour. It consists in lobules of various forms and sizes, united by an intermediate cellular tissue, and having their interstices occupied by numerous blood vessels. These lobules, by a slight maceration, may be separated and resolved into small granular masses, constituting integral portions of the gland.

The arteries of the pancreas come principally from the splenic, as it cruises along the superior margin. The veins empty into the splenic, and thus, finally, into the vena portarum. It is furnished with nerves from the solar plexus, and has lymphatics.

The excretory duct of this gland (Ductus Wirsungii) arises, by very fine roots or tubes, from each of the small granular masses. These roots have vesicular commencements like those of the sali- vary glands. The tubes coalesce into larger ones, which run transversely from the periphery towards the centre of the gland, inclining slightly, at the same time, towards the right. These secondary tubes finally discharge successively into a single one, which runs the whole length of the gland nearly in its middle. The single tube, by these additions, enlarges continually from left to right, being small where it begins at the splenic extremity of the pancreas, and about the size of a crow-quill at the duodenal. At the latter place, it is joined by the duct of the lesser pancreas, which is derived after the same rule as itself. The pancreatic

80 ORGANS OF DIGESTION.

duct, almost immediately afterwards, empties into the ductus com- munis choledochus ; or runs at the side of the latter, and makes a distinct opening near it into the duodenum, at the posterior part of the second curvature.

The diameter of the cell-like extremities of the duct of the Pan- creas is from six to twelve times greater than that of the capillary blood vessels.

BOOK V.

OF THE URINARY ORGANS.

The Urinary Organs, (Organa Uropoietica) being destined to secrete and convey the urine out of the body, consist in the Renal Capsules, the Kidneys, the Ureters, the Bladder and the Urethra.

Of the Kidneys.

The Kidneys (Renes) are two glandular bodies for the secre- tion of urine, fixed one on either side of the spine. They are in the back part of the lumbar regions, have their internal edges inclining very slightly forwards, and extend from the upper mar- gin of the eleventh dorsal to the lower margin of the second lumbar vertebra : the right, however, is ten or twelve lines lower than the left, owing to the thick posterior margin of the right lobe of the liver, which presses it downwards. The kidneys are covered in front by the peritoneum and the lumbar portions of the large intes- tine, but in such a manner as to be separated' from them, in cor- pulent subjects, by a surrounding layer of fat ; behind, they repose upon the lower part of the great muscle of the diaphragm, upon the quadrali lumborum, and upon the upper end of the psoas magni muscles.

The kidney is a hard solid body, of a brown colour; in shape it is a compressed ovoid, excavated on the margin which it pre- sents to the spine, and bears a very strong resemblance to the common kidney bean. Its flat surfaces present forwards and backwards, and the broad end of the ovoid is above. Its peri-

8*

82 URINARY ORGANS. \

phery is smooth, so that one does not infer from an external exa- mination, the lobules or internal divisions. The excavation of the kidney, called its fissure, {hilum renale) occupies about one-third of its long diameter, is bevelled in front, and leads to the very interior of the gland; conducting its blood vessels and excretory duct, which have to pass through a quantity of cellular and adipose matter. The kidneys are generally of equal size, being about four inches long, and two wide; and each one weighs three or four ounces. They have no ligaments for keeping them in position, but depend for the latter upon the adjacent cellular adhesions and blood vessels.

The kidney being destitute of a peritoneal coat, has a well marked capsule which envelops it entirely and penetrates into its fissure for some depth, where it is perforated with foramina for transmitting the blood vessels and the ureter. This capsule is white, semi-transparent, fibrous, strong, and elastic : it adheres to the surface of the kidney by delicate cellular and vascular fila- ments, which are so weak that they permit it to be stripped off' without difficulty, and when so removed, some indications of a lobu- lated condition of the organ are seen.

Of the Minute Structure of the Kidney. — The lobulated state of the kidney is well marked in the foetus; and some of the lower orders of animals, as the bullock exhibit it very clearly through life. In the human adult subject, by tearing the kidney up according to the superficial lines marking a tendency to the lobulated condition, it vv'ill be found that there are really about fifteen divisions of it, more or less, each of which constitutes a small kidney (Renculus.) When the kidney is cut open longitudinally, it obviously consists of two kinds of substance, difiering in their situations, colour, con- sistence, and texture. The one making the periphery of the gland is called from its position Cortical, [Substantia Coriicalis, Glandu- ?osa,) while the other, being more internal, is designated as the Medullary or Tubular, (Substantia MeduUaris ; Tubulosa : Fi- brosa.)

The Cortical or Secretory Substance forms the whole circum- ference of the kidney, and, on an average, is about two lines in thickness; but it is thicker at some points, as, from its internal face, processes converge towards the centre of the gland, which

THE KIDNEYS.

88

separate the tubular part into as many distinct portions of a co- noidal shape. It is composed principally of arteries and veins ramifying, among small granular corpuscles (Corpora Malpighiana or Glomeruli) that arc very distinct when viewed with a micro- scope. It tears with facility, thereby presenting this granular ap- pearance, and is of a dark or reddish brown colour, varying con- siderably, however, according to the cause of death.

The Granular corpuscles which form the mass of the cortical or secretory substance, are, individually, imperfectly visible to the naked eye, and appear like rounded points.

The celebrated Ruysch, who was distinguished for the success of his injections, and for the acuteness of his vision, declared that they consisted wholly in the very fine extremities of arteries and veins having a penicillous arrangement ; while Malpighi and Schum- lansky viewed them as purses or small sacs of a glandular cha- racter, specifically suited to secrete urine, and upon whose pari- etes the blood vessels ramified. From these granuli or acini the incipient extremities of the tubuli uriniferi they asserted take their rise.

The Tubular or Conoidal Substance, consists in from twelve to eighteen conoidal fasciculi, say on an average fifteen {Pyramides Malpigliiancc) presenting their rounded bases towards the cortical matter, and enclosed in it, while their apices converge to the cen- tral cavity of the kidney, the surface of which they form. The bodies of these pyramids, as just mentioned, are separated by pro- cesses of the cortical matter ; but tiieir apices are free, and project from the internal surface of the kidney so as to resemble as many small nipples, whence they are called Papillae or Mammellos Renales. Frequently two of the pyramids coalesce so as to form but one papilla together; in such case the latter generally pre- serves a duplicate appearance. The papillae are arranged into three vertical rows, one before, one in the middle, and another be- hind ; those of the foremost row are turned backwards ; those of the middle look hiwards; and those behind look forwards. Not unfrequenlly, there is a small depression (foveola) on the very sum- mit of the papilla. The tubular part is of a lighter colour and harder than the cortical, but the difference in these respects is not always manifest and sometimes is reversed.

84 URINARY ORGANS.

The conoidal fasciculi may each be considered, along with its appertaining cortex, as a sort of distinct gland {Renculus,) or at least as a lobe ; for upon them depends the lobulated appearance as stated of the kidney of a foetus, and of animals. Each cone, when analyzed, is found to consist in a collection of tubes {Ductus Uriniferi Bellini) converging from the circumference of the kid- ney to the apex of the papilla. These tubes are more numerous near the base of the cone, in consequence of their successive junc- tion subsequently in approaching the apex :* their terminating ori- fices, on the latter, appear like small pores, from which the urine can be squeezed in little drops.

In the early part of the course of the ductus uriniferi, while they are still in the cortical matter, they are wound about in a very serpentine and tortuous manner, and are distinguished by the name of Cortical Canals, {Ductus Ferrenii.f) They there commonly go alone, winding their way in the cortical substance until they reach its most interior face ; they then become straight, form the medul- lary substance, and have the name of the conduits or uriniferous ducts of Bellini.J

Some of the calculations on this subject are not a little curious. It was ascertained by Ferrein that iri each of the conoidal fasciculi {Pyramides Malpighiance) there were, at least seven hundred subor- dinate cones or Y>yY3imids, Pyramides Ferrenii ; and as the number of conoidal fasciculi is generally about fifteen, these pyramids would amount to ten thousand five hundred. Again, each of the subordi- nate pyramids {Pyramides Ferrenii) is composed of many hun- dred uriniferous tubes, and, by the observations of Eysenhardt,§ each of these tubes consists of twenty smaller ones. ' The cortical canals of Ferrein, it is believed by many, terminate at their peripheral extremity, by forming loops upon themselves, and anastomoses with contiguous similar canals.|| It is also held by some, as Wagner, that in addition to this mode of termination others of those canals end in caeca or blind extremities, which

* Schumlansky, Diss, de Struct. Renum, Strasburg, 1788.

t A. Ferrein; sur la Structure des reins et du foie. Mem. de Paris, 1749.

X L. Bellini, de Structura Renum Florence, 1662.

§ De Struct. Renum Obs. Micros. Berlin, 1818.

B Muller, Krause, Owen, Weber, See Muller's Physiol. 2nd ed. p. 496.

THE KIDNEYS. ' 85

are cither single or bifid. Should the observations in this respect turn out correct, the arrangement lias been at least found more de- cided and frequent in the lower animals than in man.

Huschke* and John Miillerf have denied the connexion of the Granular corpuscles with the Ducts of Ferrein. In opposition to this view, besides the testimony of preceding anatomists, we have a very good paper, by W. Bowman, of Kings' College, London,J showing by injections this connexion, and that the arteries and veins make there a tufted junction with one another.

It appears that in the Boa Constrictor, there is a vena portarum to the kidney — some approach to which the last author considers to exist in the human subject.

The Kidney receives from the aorta one or more branches, called the renal or emulgent arteries, which divide as they approach the fissure ; and having got into the substance of the gland are distributed by innumerable twigs to all parts of it. The veins equal in number the arteries, and are somewhat larger. When both, or even one, of these systems of blood vessels is injected with wax and corroded, its branches are so abundant as to retain the form of the gland. In engaging in the fissure of the kidney, the arterial ramifications are in front, the veins in the middle, and the commencement of the ureter behind. § The artery on the right side is longer than that on the left. The reverse is the case with the emulgent veins, as they empty into the vena cava ascendens. This arrangement is owing to the relative position of the aorta and the vena cava ascendens, as the first is on the left side of the spine, and the last on the right side.

The arteries of the kidneys, in ramifying minutely through its structure, adopt the following arrangem.ent. They first of all pass through the processes sent inwards from the cortical matter be- tween the Pyramids of Malpighi, or large cones, and, having got fairly into the cortical matter, they divide into very fine twigs^ which form arcades around the bases of the pyramids of Ferrein, and pass between them.|| These arcades have anastomoses with

» Ueber die Texlur der Nciren, Isis, 1828, p. 561.

+ De Gland Struct. Leips. 1830.

t Transactions Royal Society, London, Part 1st, 1842.

§ This rule is subject to frequent variations.

I) Schumlansky.

86 UEINARY ORGANS.

each other, and their larger branches go almost exclusively to the cortical substance, but few of them being found on the tubular. The branches radiate from the convexities of the arches, so as to surround the base of each cone, and to penetrate to the surface of the kidney. Some of these branches terminate in corresponding veins, and others on the granular corpuscles, or acini. -The con> nexion between4he corpuscles and the arteries, has been compared to that between grapes and the stems on which they grow, so as to form a bunch. The veins penetrate the substance of the kidney, and have a similar distribution ; but they are much larger than the arteries, and have free, large and numerous anastomoses. A con- nexion of the corpuscles with the veins is not quite evident, and, even if it does exist, remains yet to^be proved; at least, in the opi- nion of some anatomists: the fact, however, is well established, that fine injections will readily pass from the veins into the tubuli uriniferi. Also air blown into the ureter will pass readily into the veins.

In my own injections the corpuscles of Malpighi are seen very distinctly to be formed of convoluted arteries, I have not seen the veins under this arrangement, neither have I traced the cortical canals to these corpuscles or acini.

From the concave side of the arterial arcades very fine capil- lary branches converge in company with the ducts of Bellini in a line with them, and penetrate to the surface of the papilla renalis. Upon this surface is made a highly attenuated capillary intertex- ture, the meshes of which surround the orifices of the tubuli urini- feri. The converging arteries anastomose across the tubuli, making elongated meshes. A similar arrangement of the veins takes place from their cortical branches and arcades, it being in company with the arterial arrangement. The facility of injecting these minute tubular arteries and veins has frequently given rise to the mistake of considering them as the tubuli uriniferi themselves; an error which has been pointedly marked out by Miiller.*

The nerves of the kidneys come from the solar plexus of the sympathetic ; and adhering to the arteries cannot be traced very far through the glandular structure. The quantity of lymphatics is considerable.

The kidneys are subject to a false position : in one instance, I

* Physiol, p. 225.

THE KIDNEYS.

87

found in a young female subject, one of the kidneys in the pelvis in front of the rectum. A similar case has been seen by Professor Hensino-er.* I have met v^^ith several instances of a coalition across the spine, of the two kidneys, so as to present the appear- ance of a bilobed organ.

Oftfie Excretory Duct of tht Kidney , or the Ureter.

The Ureter is a canal which conveys the urine from the kidney to the bladder. It commences in the centre of the kidney by an enlargement called pelvis^ which branches off into three or four portions, (calices,) one above, one below, and one or two inter- mediate. Each of these calices, is divided, at its free extremity, into three or four short funnel-shaped terminations, (Infundibula.) Each of these terminations embraces by its expanded orifice, the base of a papilla, so as to permit the latter to project into it, and thereby to distil its urine there. Very frequently the number of papillro exceeds that of the infundibula, in which case two of the former project into one of the latter.

The pelvis of the kidney having emerged at the fissure behind the vessels, from being expanded and conoidal in shape is reduced to a cylindrical canal, which, properly speaking, is the ureter: the latter is about the size of a goose-quill, and descends through the lumbar region, between the peritoneum, and the psoas magnus muscle. It dips into the pelvis by crossing in front of the primi- tive iliac vessels and the internal iliac, crosses the vas deferens at the back of the bladder, and penetrating obliquely the coats of the latter, terminates in an orifice ten or twelve lines behind that of the neck of the bladder.

The excretory duct of the kidney is formed by two coats. The external is a dense, fibrous, and cellular tissue, but is destitute of any thing like muscle. The internal is a thin mucous lamina, which can be raised up without much difficulty, and is continuous, at its lower end, with the internal coat of the bladder; at the upper end, it is supposed by some anatomists to be reflected over the papillae, and even to pass for some distance into the tubuli uriniferi. This duct has considerable powers of extension, as manifested by its transmitting large calculi from the kidney, and also, by its

* Amer. Med. Jour., Vol. iii. p. 442.

88 URINARY ORGANS.

general enlargement in some cases of obstructed urethra ; its sen- sibility is exquisite when irritated by a calculus passing down it.

The walls of the tubuli uriniferi are the surface upon which the secretion of urine most probably taiies place exclusively. The mucous membrane of the pelvis of the kidney being continued over them so as to form the surface ; these canals, delicate as they are, are said to exhibit an epithelium formed of nucleated cells.

Of the Renal Capsules.

The Renal Capsules (Capsulce Renales, Renes Succenturiaii,) are two small bodies, one on either side, placed upon the upper end of the kidney. They are of a yellowish brown colour tinged with red, have no excretory ducts, and are more distinctly deve- loped and softer in the perfect fcetus than in the adult ; whence they are ranked among those organs, as the thymus gland, and others ; which, having some peculiar value in foetal existence, are perhaps unnecessary to that of the adult.* They are of a trian- gular pyramidal shape, flattened before and behind, and rest by a concave base upon the kidney ; they are about fifteen lines high and as many wide.

They are surrounded by a proper coat of lamellated dense cel- lular tissue, which, by detaching inwards its prolongations, keeps the parts of these bodies together, and marks out their divisions. In the centre of the renal capsule, a cavity may, from time to time, be found ; but, according to my own observations, nothing in our structure is less certain than its existence; and, in the opi- nion of Meckel, when found, it is the result of cadaverous decom- position. In the foetus it contains a reddish viscid fluid, which seems to consist in a large share of albumen, as it coagulates with alcohol; in children, this fluid becomes yellow: in adults it is dark brown; and in old people it is either entirely deficient, or in a re- markably small quantity.

Of the Minute Structure of the CapsulcB Renales. — The arteries of these bodies come from the emulgents, from the phrenics, and from the aorta. The veins of the right one terminate in the cava

* This opinion has been confirmed in a dissection of a fcetus, where I found the capsulee renales, though the kidneys were absent.

THE RENALE CAPSULES.

89

ascendens, and of the left in the left emulgent. Each one is divi- sible into lobes, and by a slight maceration may be reduced into lobules and small granulations. The granulations seem to have an intimate connexion with the veins, as they are easily penetrated by fluid injections from the latter. The external part is rather more consistent and yellow than the internal ; hence, a division has been adopted into cortical and medullary portions.

In the cortical portion the minute arteries and veins are about the size of the capillaries of other parts, and are of nearly uniform magnitude. They are arranged in a radiated manner, so as to run in lines from the surface towards the centre. The arteries anastomose with the adjoining branches, so as to form very long meshes: the veins do the same. On the periphery of the organ there is an ordinary capillary net-work of vessels. A spongy venous tissue composes the greater part of the medullary or more interior portion ; this spongy tissue receives the radiated venous branches of the exterior, and discharges its own blood into a large vein (Vena supra-renalis) in the interior of the organ. Miiller,* in addition to the above, says that the only cavity in this organ is the vein just alluded to, and that by forcing air into the vein the whole medullary tissue may be distended.

Examination with the microscope, by Mr. Gulliver,f exhibited the proper structure or pulp as formed of spherules, from the iT-hs to the 6^00 of an inch.

Alleged excretory ducts for these bodies have been found going to the testicle, to the pelvis of the kidney, and to the thoracic duct, but no credit is now attached to such assertions.

Corpora Wolffian a.

The Corpora Wolffiana, called after their discoverer, are small bodies found only in the earlier stages of foetal life, and of which there are scarcely any traces at the end of the fifth month. When in full development they are so large as to conceal the kidneys and the supra renal capsules, but as these latter organs grow the cor- pora Wolffiana diminish, and are finally placed lower down. They are supposed to be vicarious kidneys for the time, and they consist in

» Physiol., p. 621.

t Gerber's General Anatomy, Appendix, p. ]03. London, 1842.

Vol. II.— 9

90 URINARY ORGANS.

transverse ccecal tubes, which are numerous. They have each an excretory duct, v^^hich leads from their lower part into the Sinus Uro-genitalis. The latter is also peculiar to the foetal state, and is a tube which for the time receives the ureters, the vasa effe- rentia, the ducts of the corpora Wolffiana; and is prolonged into the urachus. The Sinus Uro-genitalis is finally divided into two branches, from one of which is evolved the urinary bladder, and from the other the vesiculee seminales.*

Of the Bladder.

The Bladder {Vesica Urinaria,) is the reservoir for the urine, and is placed in the pelvis, just behind the symphysis of the pubes. When pressed upon, as it commonly is, by the adjacent viscera, it is flattened somewhat before and behind; but removed from the body and inflated, it is an elongated sphere or an oval ; the great- est diameter of which is vertical, in regard to the linea ileo-pec- tinea. The superior end of the bladder is called the upper fundus, and the lower end the inferior fundus; the latter is rather more obtuse than the other; and between the two is the body. The neck of the bladder is its place of junction with the urethra. The form of the bladder is influenced by age and by sex ; in very young infants it is cylindroid, and owing to the smallness of the pelvis, rises up almost wholly into the abdomen. In the adult woman, who has frequently borne children, it is nearly spherical, has its greatest diameter transverse,f and is more capacious than in man.

The bladder is bounded in front by the pubes, above by the small intestine, behind by the rectum, and below by the prostate gland and the vesiculse seminalcs. From its superior end there proceeds to the umbiHcus a long conical ligament, the urachus, which is placed between the linea alba and the peritoneum, and produces a slight elevation or doubling of the latter. In mankind, the urachus is solid ; but some very rare cases are reported, in which it has been hollow, so as to permit the urine to flov*^ through it from the bladder. This anomalous conformation has generally been attended with a congenital obstruction of the urethra.J When

* Mailer's Pbys., p. 1639. t H. Cloquet, Anat. Descrip.

\ Sabatier, Anat., vol. iii. p. 19,

•rtlE BLADDER. 91

the anterior parietes of the abdomen are put upon the stretch, a semi-lunar fold of the peritoneum, as formerly mentioned, is seen to proceed, on either side of the urachus, from the lateral surface of the bladder almost to the umbilicus. These folds contain, in their free edge, the fibrous remains of the umbilical arteries of the fcEtus, called, subsequently to uterine life, the Round Liga- ments of the bladder, though they have little or no influence on its position. The bladder is also fixed in its situation by the pelvic aponeurosis, a metnbrane elsewhere described with the organs of generation.

The bladder consists of tour coats : the Peritoneal, the Muscu- lar, the Cellular, and the Mucous.

The Peritoneal Coat is very imperfect, and is derived from the part of the peritoneum which descends from the anterior parietes of the abdomen into the pelvis. It covers the upper and the pos-. terior face of the bladder, and then passes to the rectum, by sink- ing down between these two organs, so as to form the small pouch beneath the lower fundus of the bladder; the apex of this pouch reaches within an inch of the base of the prostate. The upper margin of this pouch next to the bladder, forms a strong horizon- tal doubling, stretching across the pelvis, when the rectum is empty, and is on a level with the posterior end of the vesiculae seminales. Being connected to the subjacent muscular coat by a thin lamina of loose cellular membrane, the peritoneum may be dissected ofl' without difficulty. In considerable distentions of the bladder, it is reflected from the upper end of the latter to the abdominal mus- cles in a line much above the pubes ; whereby a good opportunity is aflbrdcd of reaching, with an instrument, the cavity of the blad- der without injuring the peritoneum.

The Muscular Coat is of a thickness intermediate to that of the stomach and of the oesophagus, and its fibres are pale. They pass in very varied directions,* and are collected into flattened fasciculi, leaving interstices between them, through which the internal coat is occasionally caused to protrude, in strictures and other obstruc- tions of the urethra. Many of these fasciculi, arise about the neck of the bladder, and ascending upwards, before, behind, and laterally, terminate at the superior fundus in the base of the urachus. Within

* Santorini, Septemd. Tabul.

92 URINARY ORGANS.

these, which may be considered as the longitudinal fibres of the bladder, there are others forming a thinner lamina, whose course is transverse, or oblique : they serve to connect the preceding. As the muscular fibres are collected at the neck of the bladder, and at the urachus, there is, of course, an increased thickness at these points.

The Cellular Coat {Tunica 'propria) like that of the alimentary canal consists in a close, dense, lamellated, and filamentous cellu- lar tissue, very extensible and difficult to tear. It is impervious to water, adheres closely to the muscular coat without, and to the mucous within, so as to form a strong bond'of union between them. It is pervaded by many vessels and nerves, which it conveys to the mucous coat.

The Mucous Coat is also called the villous, but is much more smooth than the corresponding one of the stomach. It is white, with a slight tinge of red, and abounds with mucous follicles, which, though small and scarcely discernible in a natural state, are rendered very obvious by disease. It stretches with much fa- cility, but, like other mucous membranes, does not restore itself fully, and is rather thrown in the contracted state of the bladder, into wrinkles or folds, having a diversified course, and of a fugi- tive character, as they disappear again upon the next distention. It is very vascular.

The internal face of this coat presents, at its inferior part, the following appearances :

1. The Yes\Q,di\TY\^.n^e {Trigonus Lieutaudi, Trigone Vesicate) is placed immediately behind and below the neck of the bladder, occupying the space between it and the orifices of the ureters. It is an equilateral triangle of an inch in length, its surface is smooth, is not affected very materially in extent either by the dilatation or the contraction of the bladder, and is elevated so as to be suffi- ciently distinct and well defined.

2. The anterior angle of the triangle looks into the orifice of the urethra, and is generally so elevated that it has obtained the name of Uvula Vesicae; it is, however, simply a projection of the mu- cous membrane depending upon the subjacent third lobe of the pros- tate ; which, at this point, is not unfrequently much enlarged in the

THE BLADDER. 93

aged, and then presents a great difiiculty in the introduction of a catheter.

3. The Orifices of the ureters form the posterior angles of the triangle, and are contracted somewhat below the size of the canals themselves. They are said by Sir Charles Bell,* to be furnished, each one, with a small fasciculus of muscular fibres, which runs backwards from the orifice of the urethra, just beneath the lateral margins of the triangle, and, in its contraction, will stretch the ori- fice of the ureter so as to permit an easy passage of the urine into the bladder. The retrogradation of the urine is prevented by the ureter passing obliquely, for six or eight lines, between the muscu- lar and the mucous coat; there is something also in the obliquity of the orifice itself which assists in this eflfect ; as I have ascertained by removing the muscular coat entirely, at this point, and dissect- ing up the ureter, notwithstanding which, the bladder, when in- flated, still retained its contents. Where the ureter penetrates the muscular coat, there is often found a layer of longitudinal muscular fibres ascending and enveloping it for half an inch, or an inch.

4. The Inferior Fundus of the bladder (Bas-fond of the French) is a depression of the general concavity of the bladder, of about six lines in depth, placed between the base of the vesical triangle and the posterior side of the bladder. In the erect position, calcu- lus, when present, lodges there.

5. The Internal Orifice of the neck of the bladder resembles strongly that of a Florence flask, modified, however, by the pro- jection of the uvula vesicas, which makes it somewhat crescentic below. The neck of the bladder penetrates the prostate gland, but, at its commencement, is surrounded by loose cellular tissue containing a very large and abundant plexus of veins.f The in- ternal layer of muscular fibres is here transverse ; and they cross and intermix with each other in different directions, forming a close compact tissue, which has the effect of a particular apparatus for retaining the urine, and is called Musculus ^hincter Vesicae

* Med. Chir. Trans. Vol. iii.

t Mascagni, Anat. Univ. Str. Prim. Tab. Spec. Fig. V. 9*

94 URINARY ORGANS.

Urinariae. Generally, anatomists have not considered this struc- ture as distinct from the muscular coat at large; but Sir Charles Bell, late Professor in tlie University of Edinburgh, whose reputa- tion as an anatomist is well established, gives the following account of it.

" Begin the dissection by taking off the inner membrane of the bladder from around the orifice of the urethra. A set of fibres will be discovered, on the lower half of the orifice, which, being care- fully dissected, will be found to run in a semicircular form round the urethra. These fibres make a band of about half an inch in breadth, particularly strong on the lower part of the opening, and, having mounted a little above the orifice, on each side, they dis- pose of a portion of their fibres in the substance of the bladder. A smaller and somewhat weaker set of fibres will be seen to complete their course, surrounding the orifice on the upper part ; to these sphincter fibres a bridle is joined, which comes from the union of the muscles of the ureters."*

After repeated observations on this point, I have come to the conclusion that Mr. Bell has indicated a real structure ; but my own dissections have resulted as follows: The inferior semicir- cumference of the neck of the bladder is defined by a thick fasci- culus of muscular fibre, half an inch wide, running in a transverse direction, and having its ends attached to the lateral lobes of the Prostate Gland, being above the third lobe of the latter. This fas- ciculus is perfectly distinct from the ordinary muscular fibre of the; bladder, and resembles in its texture the musculo-fibrous coat of the arteries. The superior semicircumference is also surrounded by a thin layer of muscular fibres of an ordinary kind, forming a broad, thin band of a crescentic shape, the lower ends of which are insen- sibly lost in the adjacent muscular coat of the bladder by being spread out. And, lastly, beneath the mucous membrane of the ve- sical triangle, there is a triangular muscle of the same size as the vesical triangle. Having elongated angles, the anterior angle may be traced to the posterior part of the caput gallinaginis, and the posterior angles to the orifices of the ureters and the adjacent part of the bladder* ThQ texture of this muscle is, also, like that of the musculo-fibrous coat of the arteries. When a bladder is recent, this detail of structure is made out with difficulty : it re-

» Diseases of the Urethra, &c., p. 10. Lond. 182.0,

THE BLADDER. 95

quires to be previously hardened in spirits of wine. That a power exists in the neck of the bladder of retaining completely the urine, has been satisfactorily demonstrated to me in a case of fis- tula in perineo, which was presented to the notice of the late Dr. Physick and myself, some years ago.*

Occasionally there exists on each side of the neck of the blad- der, passing from it to the pubes, a muscle of half an inch in breadth, the effect of which is to draw the neck of the bladder towards the symphysis pubis. This, called by some the muscle of Wilson, or the Compressor Urethrae has also an influence in retaining the urine. When it exists in a distinct state it is evidently, the anterior fasciculus more detached than usual of the Levator Ani; but under ordinary circumstances it appears as the anterior margin of that muscle, and