294 THE DIGESTIVE ORGANS. 



branches of the portal system. Whether the capillaries of the 

 hepatic artery pass as such into the hepatic lobules is difficult to 

 say, since injection masses forced into the hepatic artery pass over 

 into the terminal branches of the portal vein and vice versa. 

 This question needs, therefore, further investigation. The smaller 

 divisions of the hepatic artery constitute, therefore, internal radi- 

 cals of the portal vein, since they are within the liver itself. 

 The relations of the various blood-vessels within the lobule are in 

 themselves somewhat difficult of comprehension, but the whole be- 

 comes still more complicated when the reciprocal relations of the 

 vessels and bile capillaries are taken into consideration. In order 

 to understand the structure of the liver lobule, with its hepatic 

 cords, vessels, and bile capillaries, the following points should be 

 borne in mind : The course of the bile capillaries is along the sur- 

 faces, and that of the blood-vessels along the angles of the hepatic 

 cells ; every cell comes in contact with a bile capillary and a blood 



Boundary of - 

 lobule. 



- Intralobular 

 vein. 



Fig. 235. Reticulum (Gitterfasern) of dog's liver; X I2 (gold-chlorid method). 



capillary. The latter, however, do not come in contact with the 

 former, but in man are separated by at least half the breadth of a 

 hepatic cell. In animals in which the bile capillaries are bounded 

 by more than two cells, the blood-vessels extend along the outer 

 sides of the hepatic cells ; here the bile and blood capillaries are 

 separated from each other by the breadth of a whole cell. 



The connective tissue within the hepatic lobules presents points 

 of interest which, however, are not demonstrable in organs treated 

 by ordinary methods. But when the liver tissue is treated by a 

 certain special method (see page 307), an astounding number of fibers 

 are seen extending in regular arrangement from the periphery toward 

 the central vein. These fibers are extremely delicate, of nearly 



