THE LIVER 419 



leod and Fearce, Amer. Jour. Physiol., vol. 35, 1914), is peculiar in 

 that: (1) the greater portion of the blood has already passed through 

 the capillaries of the digestive organs before entering the liver; (2) 

 its arterial supply is relatively meager and supplies only the connective 

 tissue framework, intermingling with the portal blood at the periphery 

 of the lobule; (3) its intralobular capillaries are extremely abundant 

 and are in intimate relation with the hepatic cells, each cell coming into 

 contact with four to six capillary vessels. 



The course of the blood through the vessels of the liver will be 

 readily appreciated by reference to the following table which indicates 

 the succession of the hepatic blood-vessels: 



1. Portal vein 1. Hepatic artery 



2. Interlobular veins 2. Interlobular arteries 



3. Branches to lobule 3. Vaginal branches and capillaries 



in Glisson's capsule 



4. Intralobular capillaries 



5. Central vein (intralobular) 



6. Sublobular veins 



7. Hepatic veins 



8. Vena cava inferior 



The three classes of veins, interlobular, central, and sublobular are 

 readily differentiated by the fact that the two latter lie alone, while the 

 interlobular veins are always in company with the ducts and arteries 

 within the portal canals. Moreover the central vein has almost no con- 

 nective tissue wall until near its exit from the lobule, where it passes 

 into the sublobular branches; the sublobular veins, on the other hand, 

 possess a relatively thick connective tissue wall and even some smooth 

 muscle, except in the very smallest, which are to be regarded as mere 

 interlobular continuations of central veins which soon unite to form 

 the larger sublobular vessels. 



Lymphatics. The lymphatics of the liver may be considered as con- 

 sisting of a superficial set which supplies the hepatic peritoneum and 

 the capsule of the liver, and which is continuous with a deeper set in 

 Glisson's capsule. The lymphatics of the deep set begin as perivascular 

 spaces within the lobule, from which the lymph enters larger lymphatic 

 vessels in the interlobular connective tissue, 'which follow the vessels of 

 the portal canals to their exit from the liver ; the larger lymphatics pass 

 to the abdominal lymph nodes. Other lymphatics follow the sublobular 

 and hepatic veins and pass to the mediastinal lymph nodes. 



