SHE LIVER. SECRETION OP BILE. 585 



larger vessels, ducts, &c.) the intralobular veins commence directly from their 

 surface ; and the minute venules of which each is composed may be seen in an 

 ordinary injection, converging from the circumference towards the centre, as in 

 the transverse section of other lobules. The intralobular veins terminate in 

 the larger trunks, which pass along the bases of the lobules, collecting from them 

 their venous blood ; these are called by Mr. Kiernan sullobular veins. The 

 main trunk of the Hepatic Vein terminates in the ascending Vena Cava. 



625. The Hepatic Duct forms, by 

 its subdivision and ramification, an 

 interlobular plexus very like that 

 of the portal vein; but the anasto- 

 mosis between the branches going 

 to the different lobules is less inti- 

 mate than that of the interlobular 

 veins, and cannot be directly de- 

 monstrated } although Mr. Kiernan 

 thinks that his experiments leave 

 but little doubt of its existence 

 a communication (which cannot be 

 seen to be established by any nearer 



channel) being proved to exist be- Horizontal section of two superficial Lobules, showing 



tween the right and left primary J^e interlobular &* of Biliary Dwts: 1,1, intralobu- 



i i ... / , i j rni lar vems 5 2 > 2 > trunks of biliary ducts, proceeding from 



subdivisions of the duct. The in- the plexus which traverges the lobuleg; 3j interlobular 



terlobular ducts ramify upon the tissue ; 4, parenchyma of the lobules. 



capsular surface of the lobules, with 



the branches of the portal vein and hepatic artery ; they then enter its substance, 

 and subdivide into minute branches, which are believed to anastomose with each 

 other, and to form a reticulated plexus, termed by Mr. K. the lobular biliary 

 plexus (Fig. 154). This plexus constitutes the principal part of the substance 

 of the lobule; and when seen through the meshes of the portal plexus, gives rise 

 to the appearance of caecal terminations of ducts. No such terminations of these 

 ducts have been traced, however, in the adult liver of any of the higher animals, 

 although they are sufficiently evident in the embryonic condition. From the 

 analogy of other organs, there would seem good reason to believe that the ulti- 

 mate ramifications of the hepatic ducts anastomose freely together, and that they 

 form a network, in which their terminations are lost, as it were, without forming 

 true caeca. This view of the matter finds confirmation in the curious fact pointed 

 out by Mr. Kiernan, that, in the left lateral ligament, the essential parts of a 

 lobule are found in the simplest form and arrangement. From the edge of the 

 liver next to the ligament, numerous ducts emerge, which ramify between the 

 two layers of peritoneum of which the ligament is composed. They are ac- 

 companied by branches of the portal and hepatic veins, and of the hepatic artery ; 

 which also ramify in this ligament, especially around the parietes of the ducts. 

 These ducts, of which some are occasionally of considerable size, divide, subdivide 

 and anastomose with each other ; and the meshes formed by the network of 

 larger or excreting ducts are occupied by minute plexuses of their ultimate 

 ramifications or secreting ducts. The more recent observations of Dr. Leidy 

 (loc. cit.) harmonize precisely with the view promulgated by Mr. Kiernan, and 

 seem to confirm the idea, that here, as elsewhere, the hepatic cells are inclosed 

 in a limitary membrane. " Th'e lobules are composed of an intertexture of 

 biliary tubes (Fig. 155) ; and in the interspaces of the network the bloodvessels 

 ramify and form among themselves an intricate anastomosis, the whole being 

 intimately connected together by a combination of the white fibrous and the 

 yellow elastic tissue. In structure, the biliary tubes (Figs. 155, 156) corre- 

 spond with those of Invertebrata, consisting of cylinders of basement-membrane, 



