186 MANUAL OF HISTOLOGY. 



the deposit of bile-pigment takes place at the centres of the 

 lobules about the intralobular veins ; whereas a fatty infiltra- 

 tion, such as may occur in normal livers, takes place at the 

 periphery. Not uncommonly the yellowish red color at the 

 boundary of the lobules exists under the form of delicate 

 markings, which are nothing more than the empty interlobular 

 branches of the portal vein. 



Kiernan occasionally observed in young subjects that the portal vein was 

 distended with blood, while the hepatic vein was empty. In such cases the 

 periphery of the lobules was of a darker color than their centres. 



The blood-vessels of the liver. These have been partly de- 

 scribed above. The hepatic artery, and duct, and portal vein 

 enter the liver at the transverse fissure, enclosed within Glis- 

 son's capsule, and continuously subdivide as they push their 

 way through the parenchyma. The subdivisions of the portal 

 vein never anastomose, but are distributed around the surfaces 

 of the lobules, forming their boundaries. At the periphery 

 they break up into capillaries which enter the lobules. These 

 are about 0.02 mm. in diameter, and form a network, the 

 meshes of which are scarcely wider than capillaries. Within the 

 lobule the capillaries unite to form the central vein, and these 

 then empty into branches of the hepatic vein. The subdivi- 

 sions of the hepatic vein are also devoid of anastomoses, but 

 after traversing the posterior -portion of the liver in canals 

 (which they embrace closely), unite to form the hepatic vein. 

 A peculiarity of this latter vein is the fact that its larger 

 branches give off successively small lateral twigs, which enter 

 the bases of the neighboring lobules, so that after dividing 

 such a branch lengthwise it would seem to be pierced by small 

 circular openings, which are the orifices of the lateral branches. 



Not unfrequently a central (hepatic) vein will divide into 

 two branches within a lobule, in which case the latter seems 

 to possess two apices, which become joined together as we ap- 

 proach its base. The connection between the portal and hepatic 

 veins takes place only through, their capillaries. 



The hepatic artery is comparatively small. It enters the 

 liver together with the duct and portal vein, and at once breaks 

 up into branches, which, anastomosing with each other, form a 

 large-meshed network. The arterial branches are distributed 

 to the vessels mentioned, which they enclose, and also to the 



