THE LIVER AND BILIARY APPARATUS. 



185 



lobular canals, the parenchyma of contiguous lobules appears 

 to coalesce. 



Nevertheless, the substance of the human liver can be di- 

 vided into distinct lobules, and the terminal branches of the 

 portal veins may be regarded as their natural boundaries (Figs. 

 80 and 87). Starting with the portal veins, therefore, the course 

 of the blood is as follows : portal veins, interlobular veins, cap- 

 illaries, intralobular veins, hepatic veins, and inferior vena 

 cava. 



Sublobular veins, according to Kiernan, are such branches of the hepatic 

 vein as are placed under the bases of several lobules, and collect the blood 

 from their central veins. 



The liver may be injected either through the portal or he- 

 patic veins, or through both. Good specimens may be ob- 

 tained by injecting the fresh liver of a dog or rabbit with 

 carmine - gelatine through 

 the portal vein, then inject- 

 ing fluid Berlin blue into the 

 hepatic vein, and afterward 

 hardening the organ in alco- 

 hol. The central vein and 

 adjacent capillaries will thus 

 be filled with a blue mass, 

 while the interlobular and 

 portal veins, with the per- 

 ipheral capillaries, will con- 

 tain the transparent red 

 mass. 



The color of the cut sur- 

 face of the liver in its natu- 

 ral condition is of a uniform reddish brown tint, and its lobular 

 structure is not readily made out. Usually, however, we find 

 two shades or gradations in color ; one, corresponding to the 

 central veins of the lobules, is of a dark red ; the other, corre- 

 sponding to the periphery of the lobules, is a lighter and yel- 

 lowish red. 



Occasionally these conditions are found to be reversed, 

 and the difference of color is due to the fact that after death 

 the central and other hepatic veins are filled with blood, while 

 the portal and its branches are empty ; and also because 



FIG. 81. TranRVPrce Fection of a human lobule, 

 showing opening for central vein. Ecker. 



