lobular or hepatic veins; I, congested patches extending to the circumference of the lobules; F, uncongested portions. In Fig. 347, the lobules are in a state of portal venous congestion; not a common occurrence. It has been seen by Mr. Kiernan in children only.

The view of Mr. Kiernan has been held to explain also the diversity

Fig. 348.

other.

of the statement of anatomists as to the relative position of the red and yellow substances, which have been considered to compose the liver: the red is the congested portion of the lobules, whilst the yellow is the non-congested portion in which the biliary plexus appears more or less distinctly.

The liver has two coats;the outer, derived from the peritoneum, which is very thin, transparent, easily lacerable, and vascular, and is the seat of the secretion effected by serous membranes in general. It does not cover the posterior part, or the excavation for the gall-bladder, the vena cava, or the fissures in the concave surface of the liver. The inner coat is the proper membrane of the liver. It is thin, but not easily torn, and covers not only every part of the surface of the liver, but the large vessels that are proper to the organ. The condensed areolar substance, which unites the sinus of the vena portæ and its two great branches, the hepatic artery, common biliary duct, lymphatic glands,

1. External or peritoneal coat. 2. Areolar coat with its vessels injected. 3. Mucous coat covered with wrinkles. 4, 4. Valves, formed by this coat in the neck of gall-bladder. 5, 5. Orifices of mucous follicles at this point.

Fig. 349.

lymphatic vessels, and nerves in the transverse fossa or fissure of the liver,-was described by Glisson as a capsule; and hence has been called capsule of Glisson. It connects the various anatomical elements of the liver together.

The gall-bladder (Figs. 300 and 348) is a small mem

injected.

1. Cystic artery. 2. Branches of it which supply the peritoneal coat of the liver. 3. Branch of the hepatic artery which goes to gall-bladder. 4. Lymphatics of gallbladder.

shape, situate at the inferior and concave surface of the liver to which it is attached;

and above the colon and duodenum. A quantity of bile is usually found in it. It is not met with in all animals; is wanting in the elephant, horse, stag, camel, rhinoceros, and goat; in certain of the cetacea; in some birds, as the ostrich, pigeon, and parrot; and is occasionally so in man. No traces of it are met with in the invertebrata. It may be looked upon as a dilatation of the gall-ducts, and adapted for the reception and retention of bile. Its largest part or fundus is turned forwards; and, when filled, frequently projects beyond the anterior margin of the liver. Its narrowest portion, cervix or neck, is turned backwards, and terminates in the cystic duct. Externally, it is partly covered by the peritoneum, which attaches it to the liver, and to which it is, moreover, adherent by areolar tissue and vessels. Internally, it is rugous; the folds being reticulated, and appearing somewhat like the cells of a honeycomb.

Anatomists have differed with regard to the number of coats proper to the gall-bladder. Some have described two only;-the peritoneal and mucous; others have added an intermediate areolar coat; whilst others have reckoned four;—a peritoneal,—a thin stratum of muscular fibres passing in different directions, and of a pale colour,-an areolar coat, in which a number of blood vessels is situate, and an internal mucous coat. The existence of the muscular coat has been denied by perhaps the generality of anatomists; but there is reason for believing in its existence. Amussat saw muscular fibres distinctly in a gallbladder dilated by calculi; and Dr. Monro (Tertius),' Professor of Anatomy in the University of Edinburgh, asserts, that he has seen it contract, in a living animal, for half an hour, under mechanical irritation, and assume the shape of an hour-glass. The mucous coat forms the ruge to which we have already alluded. In the neck, and beginning of the cystic duct, there are from three to seven-sometimes twelvesemilunar duplicatures, which retard the flow of any fluids inwards or outwards. These are sometimes arranged spirally, so as to form a kind of valve, according to M. Amussat.2

On the inner surface of the gall-bladder, especially near its neck, numerous follicles exist, the secretion from which is said to fill the gall-bladder, when that of the bile has been interrupted by disease, as in yellow-fever, scirrhus of the liver, &c. The hepatic duct is the common trunk of all the excretory vessels of the liver; and makes its exit from that organ by the transverse fissure. It is an inch and a half in length, and about the diameter of an ordinary writingquill. It is joined, at a very acute angle, by the duct from the gallbladder-cystic duct-to form the ductus communis choledochus. The cystic duct is about the same length as the hepatic. The ductus communis choledochus is about three, or three and a half inches long. It descends behind the right extremity of the pancreas, through its substance; passes for an inch obliquely between the coats of the duodenum, diminishing in diameter; and ultimately terminates by a yet more contracted orifice on the inner surface of the intestine, at the

Elements of the Anatomy of the Human Body, Edinb., 1825. 2 Magendie, Précis, &c., ii. 464.

distance of three or four inches from the stomach. The structure of all these ducts is the same. The external coat is thick, dense, strong, and generally supposed to be of an areolar character; the inner is a mucous membrane, like that which lines the gall-bladder.

The secretion of bile is probably effected like that of other glandular organs; modified, of course, by the peculiar structure of the liver. We have seen, that the organ differs from every other secretory apparatus, in having two kinds of blood distributed to it ;-arterial by the hepatic artery; and venous by the vena porta. A question has consequently arisen-from which of these is the bile formed? Anatomical inspection does not positively settle the question; and, accordingly, argument is all that can be adduced on one side or the other. The most common and the oldest opinion is, that the bile is separated from the blood of the vena portæ; and the chief reasons brought forward in favour of the belief, are the following: First. The blood of the portal system is better adapted than arterial blood for the formation of bile, on account of its having, like all venous blood, more carbon and hydrogen, which are necessary for the production of a humour as fat and oily as the bile; and, as the experiments of Schultz' and others have proved, that portal blood contains more fat than that of other veins and arteries, it has been imagined, by some, that the blood, in crossing the omentum, becomes loaded with fat. Secondly. The vena portæ ramifies in the liver after the manner of an artery, and evidently communicates with the secretory vessels of the bile. Thirdly. It is larger than the hepatic artery; and more in proportion to the size of the liver; the hepatic artery seeming to be merely for the nutrition of the liver, as the bronchial artery is for that of the lung.

In answer to these positions, it has been argued. First. That there seems to be no more reason why the bile should be formed from venous blood than other fatty and oleaginous humours,-marrow and fat for example, which are derived from arterial blood. It is asked, too, whether, in point of fact, the blood of the vena portæ is more rich in carbon and hydrogen? and whether there be a closer chemical relation between bile and the blood of the vena portæ, than between fat and arterial blood? The notion of the absorption of fat from the omentum, it is properly urged, is totally gratuitous. Secondly. The vena portæ does not exist in the invertebrated animals; and yet, in a number of them, there is an hepatic apparatus, and a secretion of bile. Thirdly. Admitting that the vena portæ is distributed to the liver after the manner of an artery; is it clear, it has been asked, that it is inservient to the biliary secretion? Fourthly. If the vena portæ be more in proportion to the size of the liver than the hepatic artery, the latter appears to bear a better ratio to the quantity of bile secreted: and, Lastly. It is probable, as has been shown in another place, that the liver has other functions connected with the portal system, in the admixture of heterogeneous liquids absorbed from the intestinal canal; and, it may be, in depriving the blood of the vena portæ of principles

1 Rust's Magazine, B. xliv.; or Gazette Médicale, Aug. 15, 1835.

which go to the formation of bile and might be unfit for assimilation, if transported into the blood of the general system.

In the absence of accurate knowledge derived from direct experiment, physiologists have usually embraced one or other of these exclusive views. The generality, as we have remarked, assign the function to the vena porta. Bichat, on the other hand, ascribes it to the hepatic artery. M. Broussais1 thinks it probable, that the blood of the vena portæ is not foreign to the formation of bile, since it is confounded with that of the hepatic artery in the parenchyma of the liver; "but to say with the older writers, that the bile can only be formed from venous blood, is, in our opinion," he remarks, "to advance too bold a position, since the hepatic arteries send branches to each of the glandular acini, that compose the liver." M. Magendie likewise concludes, that nothing militates against the idea of both kinds of blood participating in the secretion; and that it is supported by anatomy, as injections prove, that all the vessels of the liver,-arterial, venous, lymphatic, and excretory, communicate with each other. Mr. Kiernan, as we have seen, considers that the blood of the hepatic artery, after having nourished the liver, is inservient to the secretion, but not until it has become venous, and entered the portal veins. He,-with all those that coincide with him in the morphological arrangement of the liver-denies that there is any communication between the ducts and bloodvessels; and asserts, that if injections pass between them, it is owing to the rupture of the coats of the vessels. Experiments on pigeons, by M. Simon, of Metz, showed, that when the hepatic artery was tied, the secretion of bile continued, but that if the portal and hepatic veins were tied, no trace of bile was subsequently found in the liver. It would thence appear, that in these animals the secretion of bile takes place from venous blood. But inferences from the ligature of those vessels have been very discordant. In two cases, in which Mr. Phillips tied the hepatic artery, the secretion of bile was uninterrupted, yet the same thing was observed in three other cases, in which the ligature was applied to the trunk of the vena porta.

The view, that ascribes the bile to the hepatic artery, has always appeared to the author the most probable. It has all analogy in its favour. There has been no disputed origin as regards the other secretions, excepting, of late, in the case of the urinary. All proceed from arterial blood; and function sufficient, we have seen, can be assigned to the portal system, without conceiving it to be concerned in the formation of bile. We have, moreover, morbid cases, which would seem to show that bile can be formed from the blood of the hepatic artery. Mr. Abernethy3 met with an instance, in which the trunk of the vena portæ terminated in the vena cava; yet bile was found in the biliary ducts. A similar case is given by Mr. Lawrence; and Professor Monro3 details a case communicated to him by the late Mr.

1 Traité de Physiologie, &c., Drs. Bell's and La Roche's translation, 3d edit., p. 456, Philad., 1832.

2 Edinburgh Med. and Surg. Journal, xc. 229.

3 Philosoph. Transact., vol. lxxxiii.

• Elements of Anatomy, Edinb., 1825.

4 Medico-Chirurgical Transact., iv. 174.

Wilson, then of the Windmill Street School, in which there was reason to suppose, that the greater part of the bile had been derived from the hepatic artery. The patient, a female, thirteen years old, died from the effects of an injury of the head. On dissection, Mr. Wilson found a large swelling at the root of the mesentery, consisting of several absorbent glands in a scrofulous state. Upon cutting into the mass, he accidentally observed a large vein passing directly from it into the vena cava inferior, which on dissection, proved to be the vena portæ ; and on tracing the vessels entering into it, one proved to be the inferior mesenteric vein: and another, which came directly to meet it, from behind the stomach, proved to be a branch of the splenic vein, but somewhat larger, which ran upwards by the side of the vena cava inferior, and entered that vein immediately before it passes behind the liver. Mr. Wilson traced the branches of the trunk of the vessel corresponding to the vena portæ sufficiently far in the mesentery and mesocolon to be convinced, that it was the only vessel that returned the blood from the small intestines, and from the cæcum and colon of the large intestines. He could trace no vein passing into the liver at the cavity of the porta; but a small one descended from the little epiploon, and soon joined one of the larger branches of the splenic vein. The hepatic artery came off in a distinct trunk from the aorta, and ran directly to the liver. It was much larger than usual. The greater size of the hepatic artery, in this case, would favour the idea, that the arterial blood had to execute some office, that ordinarily belongs to the vena porta. Was this the formation of bile? The case seems, too, to show, that bile can be formed from the blood of the hepatic artery.

Professor Gintrac1 has published a case in which there was ossification with obliteration of the vena porta. The patient died of ascites. The liver was pale or whitish, and irregularly wrinkled or mammillated on its surface. The gall-bladder contained a medium quantity of thickish yellow bile. The biliary ducts were normal. The vena portæ above the junction of the splenic and superior mesenteric veins was completely filled by an old clot, which adhered to the inner membrane. The clot was solid, and of a deepish black colour. At the same part of the vein several osseous plates were observed many lines in diameter, which were situate between the inner and middle coats of the vein, without having much adherence to either. All the abdominal veins that ended in these vessels were gorged with blood, and varicose. Professor Gintrac ascribed the ascites to the obliteration and ossification of the vena portæ, and he considered the case to prove, that although obliteration of that vessel probably modified the secretion of bile, it did not prevent it altogether; but interfered materially with the nutrition of the liver. Hence, he inferred, that the blood of the vena portæ contributes to the nutrition of the liver; but is not indispensable to the secretion of bile.

In Professor Hall's patient, the vena portæ and its bifurcation were completely filled with encephaloid matter, so that no blood could pass 1 Cited in Amer. Journal of the Med. Sciences, Oct., 1844, p. 476.

2 P. 304.