132 GLANDS. 



stitute an epithelial network, which is interwoven thus 

 with the web of capillary vessels. The elements of 

 the liver which we have studied thus far constitute 

 its glycogenous apparatus. 



Hepatic duct. The hepatic duct enters the liver at its transverse 

 fissure along with the hepatic artery and portal vein, 

 and accompanies these vessels to the lobules. In its 

 course it gives off a great many arborescent branches, 

 of which the larger anastomose frequently with each 

 other, whilst the smaller ones remain solitary and 

 continue on to the surfaces of the lobules. From 

 these minute perilobular ramifications arises a set of 

 capillary tubes which enter the substance of the 

 lobules not very deeply and there terminate in 

 blind extremities ; they are lined within by a simple 

 epithelial layer, made up of the smaller cells which 

 have been described above (PL XXII. fig. VI. 5, 6, 

 7). In the biliary ducts which possess a diameter 

 beyond sVth of a line, according to Kolliker, their 

 pavement epithelium is replaced by a cylindrical epi- 

 thelium. Finally, the hepatic ducts proper, together 

 with the cystic duct and the ductu-s communis chole- 

 doclius have muscular fibres in their walls, and also a 

 considerable number of minute racemose glands. The 

 hepatic artery accompanies the hepatic ducts to the 

 lobules, supplies them with very numerous branches, 

 and finally terminates in the capillary plexus of the 

 portal vein. This second apparatus, composed of the 

 biliary ducts and the hepatic artery, constitutes a 

 tubular gland. The liver then is made up of two 

 glands, which are intimately intermingled with each 

 other ; one of these (a blood-gland) is concerned in 



