LIVKK. 



L1VKK. 





by a third set, the hepatic wine, which iesue from the liver at it* poste- 

 rior border, and immediately enter the inferior vena cava near the heart 

 The ultimate arrangement of these different Wood-vessels in the 

 Hirer it wry peculiar : it was first accurately described by Mr. Kiernan. 

 When the substance of the liver U torn, it is seen to be composed of 

 innumerable granule* of about the of a pin's head ; each of these 

 contain* the ileeaenta of a liver. They are connected most intimately 

 with the branches of the hepatic vein, a small twig of which is con- 

 in the interior of each, while on their exterior surface and in 

 interstices ran branch** of the portal vein, hepatic artery, and 

 The mass of each granule or lobule is constituted in great 

 put of a dose network of capillary blood-vessels, which communicate 

 on the exterior with the email branche* of the portal, and on the 

 interior with the twig of the hepatic vein. The blood brought by the 

 portal vein therefore is poured into the capillary network of each 

 granule or lobule of the liver, and, after yielding in it the constituents 

 of the bile, is received into the branches of the hepatic vein, whence 

 it is transmitted to the general vascular system. The branches of the 

 htcsitk artery soon become very minute on the exterior of the lobules, 

 and few can be traced into their interior; it is probable that, after 

 having nourished the coats of the vessels and ducts, and other tissues 

 of the liver, the blood of the hepatic artery is poured into the minute 



d by the ultimate division of the portal vein, and con- 

 with the blood of that win to yield the constituent* of 

 thebOe. 



The form and disposition in the liver, of the primitive radicles of 

 the secreting canals or bile-duct*, have been the subject of much dis- 

 isstsinn Dr. Handfield Jones, in a paper in the 'Philosophical 

 Transactions,' arrive* at the following conclusions : 



" The liver in all vertebrate animals may be regarded as consisting 

 of a eeoretory parenchyma and of excretory duct*. The size of the 

 excretory apparatus bean only a small proportion to that of the 



'Then two portions of the liver are not continuous with one 



rtber, bat are disposed simply in a relation of juxtaposition. 



" The action of the liver seems to consist in the transmission of bile 

 at U is formed from cell to cell, till it arrive* in the neighbourhood 

 of the excretory duct, by which it U absorbed. This action is pro- 

 bably slow and very liable to be interfered with, contrasting remarkably 

 with that of the kidney, where a particular apparatus U added to insure 

 completeness and rapidity of action. The secretion of the hepatic 

 wilt is very liable to be retained within the gland, either in the cells 

 or in a free state. This circumstance, at well at it* structural rela- 

 tions, teem* to point oat the liver at approximating to the clars of 

 dnetleas glands. 



" For the same reason it U highly probable that a part of the 

 secretion of the cells i* directly absorbed into the blood which traverses 

 the lobules." 



From an exteualTe series of reeearche* in all classes of Vairhrala, 

 I'r. H. Jones comet to the conclusion that the excretory system of the 

 liver always terminates in doted tube*. He describes the duct* of 

 the eheep't liver, which in all essential particular* agrees with that of 

 man and the pig, at follows : 



" In the minuteet branche* (of the biliary dncte), which seem to be 

 Tr********"*; their termination, and which can sometimes be examined 

 and isolated in the most satisfactory manner, the epithelial particle* 

 are remarkably modified ; they can scarcely be said to exist as sepa- 

 rate individuals, but rather their nuclei, which are often large and 

 distinct, are eat doe* together in a tnbgranular or homogeneous basis- 



In duct* where this condition of epithelium exist* then is 

 any distinct trace of basement-membrane, the margin, though 

 eoOcientiy even, yet exhibiting the buhring outlines of the component 

 nuclei; still lees Is there any proper fibrous coat, though the dncte 

 may be more or less involved in the filamentary expansions of the 

 capsule of Oliaeon. Dncta of this character have usually a diameter 

 of about 1-lOOOth of an inch ; they can sometime* be followed for a 

 soneiderahl. distance without being seen to give off any branches, or 

 to diminish much in calibre. Their mode of terminating it various : 

 several have been distinctly teen to terminate by rounded and doted 

 extremities, which have nearly the same diameter as the duct iUelf ; 

 others teem to lose their tubular character, their nuclei become lees 

 closely set together, and the uniting substance more faintly granular 

 and indefinite, the duct in short gradually on***, losing all determi- 

 nate *troettu. In tome of rather minute site, 1 -3000th to 1 -2000th of 

 an inch in diameter, the exterior form remain* distinct, but the canal 

 is almost obliterated by the doee approximation of the nuclei of the 

 opposite wall*. These structures now described I believe to be truly 

 the terminal branches of the hepatic duct, from which they certainly 

 originate. They seem gradually to lay aside the several component 

 I of the Urge doota, the fibrous coat blending with the ramifi- 

 of Oliam'a capsule, the basement-membrane imperceptibly 

 . and the epithelium becoming resolved at lost into it* simple 



important to remark that in a dog Dr. H. Jones found Mliary 

 matter in the interlobular fissure.. From the fact that In the contents 

 of the hepatic ducte of man and the sheep, extracted by means nf a 

 forceps and without injuring the organ, hepatic cells may be detected, 

 Mr. Wharton Jonee ( Phil. Trans., 1 1848) draws the conclusion that 



the hepatic cells are endogenous cells, answering to the epithelium of 

 other glands. 



The view taken by Dr. H. Jnnes that the liver is essentially of the 

 same order as the ' ductless ' glands, and should be placed in the same 

 category a* the Peyerian follicle*, spleen, Ac., is probably correct 

 In fact, startling at this view may at first appear, a very clear 

 transition between the Peyerian follicles, kc., and the liver is afforded 

 by the -tonsils, which on the one hand are identical with Foyer's 

 follicles, in so far a* they are solid vascular networks whose meshes 

 are filled by a morphologically indifferent tissue ; while on the other 

 band, without differing from the liver in this respect, they resemble it 

 in having these element* arranged around diverticula of the intestinal 

 mucous membrane. 



The biliary canals, reduced in number by successive re-union to two 

 tubes, one from the right, the other from the left lobe of the liver, 

 issue at the transverse fissure of its under surface, there soon unite, 

 and form one main trunk, the hepatic duct After running a short 

 distance, together with the portal vein, hepatic artery, and nerves, in 

 a quantity of dense cellular tissue inclosed within the fold of the 

 peritoneum that connects the liver with the stomach, the lesser 

 amentum [PERITONEUM], the hepatic duct meet* and unites with the 

 duct of the gall-bladder, or cystic duct. The tube resulting from the 

 junction of the hepatic with the cystic duct is called the Ductus 

 Comnmnis Choledocbus : it is about 3 J inches in length, and termi- 

 nates by opening, together with the duct of the pancreas, into the 

 portion of the intestine named Duodenum, at the distance of a few 

 inches from the stomach. 



The Gail-Bladder is a pyriform membranous sac, lodged in a shallow 

 depression at the inferior surface of the liver, which communicates, 

 as we have stated, with the excretory duct of the liver, by means of 

 a tube called the Cystic Duct At times, when a supply of bile is not 

 required in the intestinal canal for instance, during fasting the bil-.- 

 flowing from the liver is impeded in its progress through the ductus 

 communis choledochus into the intestine, and U consequently obliged 

 to regurgitate through the cystic duct into the gall-bladder, which 

 serves as a temporary reservoir for the secretion, discharging it again 

 when the presence of bile is required in the intestine to aid the 

 digestive process. At the neck of the gall-bladder, close to its termi- 

 nation in the cystic duct, the lining membrane forms a spiral fold, 

 which seems destined to retard the flow of the bile from the reservoir. 

 The gall-bladder is not constantly present ; the animals in which it 

 does not exist are for the most part, though not universally, herbivo- 

 rous, and such in which digestion is constantly going on, and a 

 reservoir for bile consequently not required. But many herbivorous 

 animals have a gall-bladder ; and sometimes, where it is absent, the 

 bile-duct present* a considerable dilatation of its cavity near the 

 intestine : such is the case, for example, in the horse and elephant 



The functions of the liver are important The analysis of the fluid 

 which it secretes shows that it frees the blood from on excess of 

 matters composed of carbon and hydrogen ; and by this means, and 

 probably also by effecting some changes in the matters which have 

 been added to the blood during it* circulation through the viscera of 

 the abdomen, the liver assists in preparing that fluid for the nutrition 

 of the body. The bile seems also to have a direct influence in the 

 formation of the chyle, the nutritive fluid derived from the food ; and 

 some of it* ingredient* serve a* a natural stimulus of the peristaltic 

 action of the intestines. [BiLB.1 



The liver is developed upon the tame plan as the other glands. 



According to the latent observations, particularly of BUchoff and 

 Remak, the development of the liver may be thus best understood : 

 " The primary rudiment of the liver, which appears at a very early 

 period (about the 55th to the 58th hour in the chick ; in Mammals 

 after the Wolman bodies and the alUntou), consist* of two masses of 

 cells, an external, proceeding 'from tho fibrous membrane of the 

 intestine, and an internal epithelial, which at first form a simple and 

 afterwards a dichotomously-divided sac. Solid procesucs, the hepatic 

 cylinders of Kemak, are now developed from the epithelial lamina, 

 which, as in the intestine, consists at first of round cells, probably iu 

 many layers, by the multiplication of it* cells, and extend into tho 

 outer lamina, branching out and anastomosing, while at the same time 

 the cells of the outer lamina included in the meshes of this net- work 

 multiply and become successively changed into vessels, nerves, con- 

 nective tissue, 4c. The difficulty is to say how this peculiar reticulated 

 parenchyma of cells and rudimentary vessels become* ultimately 

 arranged a* we know it to be. In the first place, as regards the 

 hepatic-cell net-work, to which by a continual new development of 

 o-lls fresh processes are added, which unite into new networks, so 

 that the hepatic-cell net-work of the adult liver is the direct progeny 

 of the original reticulation. More detailed information concerning 

 the separate steps of the formation of the hepatic-cell net-work is at 

 present wanting ; yet from what is known it would appear to take place 

 in somewhat different modes. Sometimes, in the subsequent stages, 

 free cylindrical processes of the hepatic-cell net- work do not exist to any 

 extent; but it would appear to Increase by the continual addition of new 

 meshes at it* edges, perhspn also by the constant elongation of the exist- 

 ing columns nf hrpatio evils and the development of fresh anastomoHea 

 between them ; this is, if I have observed rightly, the cose in man, where 

 in the seventh week I did not succeed in clearly distinguishing free 



