APPENDAGES TO THE ALIMENTAEY CANAL. 



533 



the plexus, and accompany the finest ramifications of the portal 

 vein, so that the bile flows in a direction opposite to that of the 

 blood. Finally, the spaces in the islets left between the elements 

 just described are occupied by the so-called hepatic cells. Thus, in 

 general, is an islet in the human liver composed; the capillary 

 plexus, however, being common to all the contiguous islets, and 

 continuous between them. The capsule of Glisson, composed of 

 areolar tissue, invests the vena portas, hepatic artery, and hepatic 

 duct, as far as to the branches going to the islets ; but it extends 

 between, and isolates the latter into distinct lobules, only in the 

 pig, so far as has yet been ascertained. 



The passages in the liver containing Glisson's capsule with the 

 vessels just mentioned, are called the portal canals. (Fig. 364.) 



Fig. 364. 



Fig. 365. 



Fig. 364. A transverse section of a small portal canal and its vessels ; after Kiernan. 4. Portal 

 vein. 9. Interlobular branches. 5. Branches of the vein, also giving off interlobular branches 

 (vaginal branches, Kiernan.) 7. Hepatic duct. 6. Hepatic artery. 2. Hepatic vein. The lobules 

 are seen in outline. 



Fig. 365. Hepatic cells of man. a. Normal cells, b. With pigment, c. With fat Magnified 400 

 diameters. (Killiker.) 



More particularly, the hepatic cells (Fig. 365) are described by 

 Kolliker as averaging T5 V^ to TiAnr f an i n h i n diameter, the ex- 

 tremes being S oW an d ?^TT of an inch. Their membrane is smooth 

 and delicate, and their normal contents are 1st, a yellowish, gran- 

 ular, semi-fluid substance; 2c?fo/, a round, vesicular, nucleolated nu- 

 cleus, T oW to 3 oVo of an i nca i n diameter (and sometimes two of 

 these). Besides these (Sdly) fat-drops, and (4ithly) pigment-granules 

 are frequently to be met with. The last hardly exceed jzvw of 

 an inch in diameter, are of a yellow or brownish-yellow color, and 

 appear to be chemically identical with the coloring matter of the 

 bile (p. 101). 



