THE LIVER AND BILIARY APPARATUS. 191 



Division of a nucleus, as described by Kolliker, I have never been able to 

 confirm. When two nuclei are placed in contact, there may be an appear- 

 ance of division, but the actual process is not easy to see. 



Thin liver sections may be stained either in carmine fluid or 

 hsematoxylon, and preserved in glycerine or balsam. 



The larger bile-ducts. If, for the sake of convenience, we 

 imagine that the hepatic duct enters the liver to be distributed 

 to its substance, we may describe it as giving off two primary 

 branches at the transverse fissure, one passing to the right 

 lobe, the other to the left. As these branches continue their 

 course, following the subdivisions of the hepatic artery and 

 portal vein, they also undergo successive divisions, and at 

 length enter the interlobular canals. In this position their 

 diameter varies between 0.02 and 0.03 mm. 



The primary branches do not, however, pass unchanged 

 into the liver tissue. They ramify even before entering the 

 gland, but such vessels are distributed only to the under 

 surface (Henle). Other biliary ducts, given off in the trans- 

 verse fissure, form a network on the upper surface, as may be 

 demonstrated by injecting the hepatic duct with carmine-gly- 

 cerine. The branches of these networks then enter the liver- 

 tissue and ramify throughout it, following the subdivisions of 

 the hepatic artery and portal vein. 



As the divisions of the hepatic duct diminish in size, the 

 thickness of their walls undergoes proportionate diminution. 

 The trunk of the hepatic duct comprises an internal layer 

 measuring 0.15 mm. in thickness, and an external layer of 0.2 

 0.3 mm. Both of these coats are composed, according to 

 Henle, of interlacing connective-tissue bundles, in which elas- 

 tic fibres are freely intermixed. These ducts have an internal 

 lining of cylindrical epithelium, which is 0.05 mm. in height. 

 Even where the branches measure only 0.2 mm. in diameter 

 they have cylindrical epithelium surrounded by a single layer 

 of connective tissue longitudinally disposed, in which there 

 are also muscle-corpuscles, distinguished by their long, rod- 

 shaped nuclei (Heidenhain). The most minute biliary pas- 

 sages consist of a structureless membrana propria, which is 

 lined with flattened cylindrical epithelia. 



Glands of the ducts. In the trunk of the hepatic duct and 

 its subdivisions, down to those branches of which the diameter 

 is not less than 0.5 mm., the mucous membrane is provided 



