THE LIVER SECRETION OF BILE. 623 



pearance of ccecal terminations of ducts. The ultimate terminations of these ducts have 

 not, however, been traced 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 ultimate 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 cceca. 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 lobe 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 peri- 

 toneum of which the ligament is composed. They are accompanied 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 considera- 

 ble 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. 



d. The Hepatic Artery sends branches to every part of the Liver, supplying the walls of 

 the Portal and Hepatic Veins, and of the Hepatic Ducts, as well as Glisson's capsule. The 

 principal distribution of its branches, however, is to the Lobules, which they reach, in the 

 same manner with the Portal vessels and Biliary Ducts, by spreading themselves through the 

 interlobular spaces. There they ramify upon the interlobular ducts, and upon the capsular 

 surface of the lobules, which they then penetrate; their minuteness prevents their distribu- 

 tion within the lobules from being clearly demonstrable ; but, as they enter along with the 

 biliary ducts, there can be little doubt that, here as elsewhere, they are principally distributed 

 upon the walls of these. As to the ultimate termination of the capillaries of the Hepatic 

 Artery, whether they enter the Portal plexus, or the Hepatic Vein, there is a difference 

 of opinion amongst anatomists ; the former view being upheld by Kiernan, the latter by 

 Miiller. The question is a very interesting one in a physiological point of view; since, if 

 the former account be the true one, the Blood which is brought to the Liver by the Hepatic 

 Artery becomes subservient to the secretion of Bile, only by passing into the Portal plexus; 

 whilst, if the latter be the correct statement, either the arterial Blood is not at all subservient 

 to the formation of Bile, or the secretion can be elaborated from the arterial capillaries. The 

 experiments of Mr. Kiernan have satisfactorily proved, that the Intralobular or Hepatic Veins 

 cannot be filled by injection from the Hepatic Artery, though they maybe readily filled from 

 the Portal plexus; whilst, on the other hand, there is reason to believe, that a very fine in- 

 jection into the Hepatic arteries, will find its way into the Portal plexus.* It is certain that 

 all the branches of the Hepatic artery, of which the termination can be ascertained, end in 

 the Vena Portse; a free capillary communication existing between their two systems of 

 branches, on the walls of the larger blood-vessels and ducts. According to Miiller, there is 

 an ultimate plexus of capillary vessels, with which all the three systems freely communicate ; 

 but for this idea there is no adequate foundation; and it is inconsistent with the fact just stated, 

 that injection into the Hepatic Artery does not return by the Hepatic vein. And the views 

 of Mr. Kiernan have lately received important confirmation from the researches of Mr. 

 Bowman on the circulation in the Kidney ( 841). 



e. It now only remains to describe the Hepatic Veins, the branches of which occupy the 

 interior of the Lobules, and are termed intra-lobular veins (1, 1, Figs. 230 and 231). On 

 making a transverse section of a lobule, it is seen that the central vessel is formed by the 

 convergence of from four to six or eight minute venules, which arise from, the processes 

 upon the surface of the lobule. In the superficial lobules, (by which term are designated 

 those lobules which lie upon the exterior of the glandular substance, not only upon the sur- 

 face of the Liver, but also against the walls of the larger vessels, ducts, &c.,) the Intralobular 

 Veins commence directly from their surface; and the minute veriules of which each is com- 

 posed 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 tne bases of the lobules, collecting from them their 

 venous blood; these are called by Mr. Kiernan sublobular veins. The main trunk of the 

 Hepatic Vein terminates in the ascending Vena Cava. 



/. In regard to the mode in which the nucleated Cells, that are the real agents in the 

 Secreting process, are arranged in the Liver of Man and the higher animals, there is much 

 uncertainty; owing especially to our want of acquaintance with the mode in which 

 the Hepatic Ducts terminate. They would seem to form the greatest part of the Paren- 

 chyma, which fills up the interstices between the reticulations of the Blood-vessels 

 and Ducts ; but it is obvious, from their functional operation, that they must have a more 



This is stated to have been the case in the injections of Lieberkiihn, although Mr. Kier- 

 nan has not succeeded in effecting it. 



