424 



THE DIGESTIVE APPARATUS IN MAMMALIA. 



directed from the periphery towards the centre of the lobule, where they 

 unite to form the afferent vessel. It results from this arrangement that the 



hepatic cells which fill the spaces 

 between the vessels are placed in 

 radiating series. 



Efferent series. Situated in the 

 centre of the lobules, this vessel 

 receives all the ramifications of 

 the capillary plexus, and is named 

 the intralobular or central supra- 

 hepatic vein. It is voluminous, 

 and communicates with the other 

 intralobular veins. (These intra- 

 lobular veins terminate in the 

 larger trunks that run along the 

 bases of the lobules, and are named 

 the siibldbular veins.) 



Lymphatics. In a hepatic lo- 

 bule are found very fine lymphatic 

 vessels that surround the branches 

 of the hepatic plexus, where they 

 form the lymphatic vaginae, or 

 canals which contain the blood- 

 vessels. 



Connective tissue. The intra- 

 lobular connective tissue is scanty, 

 the lobule being almost entirely 

 composed of cells or capillaries ; so that only some trabeculae exist around 

 the lymphatic sheaths. There is, however, a larger quantity in the inter- 



lobular spaces ; and in some 

 animals especially the Pig 

 Glisson's capsule sends 

 somewhat thick lamellae of 

 connective tissue between 

 these lobules. 



EXCRETORY APPARATUS. 

 This is very simple in Soli- 

 peds, and is composed of a 

 vessel named the ductus chole- 

 dochus, resulting from the 

 union of several trunks lodged 

 in the posterior fissure of the 

 liver, and which come from the 

 three lobes. Traced in the 

 substance of the hepatic tissue, 

 these branches divide into 

 more and more attenuated 

 ramuscules that arise from 

 the periphery of the lobules, 

 and are continuous with the biliary ducts that envelop and penetrate these. 



Course. At its exit from the liver, the ductus choledochus is placed 

 between the layers of the gastro-hepatic omentum, and ascends to the wall of 

 the duodenum, which it passes through at about six inches from the pylorus, 



HORIZONTAL SECTION OF THREE SUPERFICIAL 

 LOBULES, SHOWING THE TWO PRINCIPAL 

 SYSTEMS OF BLOOD-VESSELS. 



a, a, Intralobular veins, terminating in the 

 hepatic veins ; 6, 6, Interlobular plexus, 

 formed by branches of the portal vein. 



Fig. 215. 



SECTION OF A SMALL PORTION OF THE LIVER OF A 

 RABBIT, WITH THE HEPATIC OR INTRALOBULAR 

 VEINS INJECTED, 



