STRUCTURE OF THE BILE DUCTS. 393 



bine, while the intervening' cells remain free from colotu-. By killing the animals 

 sooner after the injection, the blue colom-ing matter was found withm the hepatic 

 cells, thus demonstrating- that it was through theii- agency that the canals were 

 filled. Further experiments were made in animals in which the portal vein and 

 hepatic artery respectively had been tied, and the result obtained was that, when 

 the hepatic artery had been tied, the iieripheral jjarts of the lobules showed the 

 blue canals, while the centre of each was left colourless ; and that, when the 

 portal vein had been tied, the reverse effect was produced — the centre of each 

 lobule showing blue canals, while in the intervening spaces only the larger 

 ducts were seen, showing that, as previously stated, the caijillary network of the 

 lobules is in part supplied dii'cctly by the hepatic artery. 



It is still a matter of doubt whether the intercellular passages above 

 described possess proper walls distinct from the cells, or whether they 

 are to be regarded as mere channels formed by the apposition of corre- 

 sponding grooves on the sides of the cells, but the balance of evidence 

 appears to be in favour of the former supposition. It is worthy of 

 remark that the biliary capillaries are almost always found on the 

 flattened surfaces, seldom or never running along the corners of the cells. 



Lynipliatics of tlie Liver. — Lymphatics are seen on the prolonga- 

 tions of Glisson's capsule between the lobules (interlobular), where 

 they accompany the blood-vessels, and in some cases surround and 

 enclose them. They originate from the spaces around the capillaries 

 of the lobules (p. 391). In the pig's liver lymphoid follicles 

 have been noticed by Kisselew and Chrzonszczewsky, in connection 

 with the interlobular lymphatics. These deep lymphatics unite into 

 larger vessels which run along the portal canals and emerge at the 

 portal fissure. They are in communication with a close subperitoneal 

 plexus on the under surface of the organ. The corresponding plexus 

 on the upper surface communicates, through the ligaments of the 

 liver, with tlie thoracic lymj^hatics. 



Structure of the Ducts. — The larger bile-ducts have strong dis- 

 tensible areolar coats, containing abundant elastic tissue, and the 

 largest, a certain amount of plain muscular tissue. They are lined 

 with columnar epithelium. The minute ramifications between the 

 lobules have walls composed simply of a basement membrane, with a 

 lining of columnar epithelium. As they pass into the lobules, however, 

 tliis columnar epithelium becomes shorter and broader, and approaches 

 more and more in character to the hepatic cells, at the same time filling 

 up the tube so that only a very small passage is left. The basement 

 membrane is no longer complete, and the intercellular bile passages 

 open freely into the minute ducts. In the portal canals, where they 

 are somewhat larger, the ducts present numerous openings on the 

 inner surface, which are scattered irregularly in the larger ducts, but 

 in the subdivisions are arranged in two longitudinal rows, one at each 

 side of the vessel. These openings were formerly supposed to be the 

 orifices of mucous glands ; but while the main ducts are studded with 

 true mucous glands of lobulated form and with minute orifices, the 

 openings now i-eferred to belong to saccular and tubular recesses, 

 which arc often branched and anastomosing, and may be beset all over 

 with ca3cal projections (Theile). Sappey and Henle, who have made 

 these recesses the subject of special investigation, find that they are so 

 numerous as sometimes to conceal the parent tube, and on this Henle 

 w\as led to base a suggestion (System. Anat.) that they and not the liver 

 cells are engaged in the secretion of bile. 



