ALIMENTARY CANAL AND ITS APPENDAGES 413 



areas from one to two millimeters (^ to inch) in diameter. These 

 are the outer sides of the superficial layer of a vast number of 

 minute polygonal masses, or lobules, of which the liver is built up; 

 similar areas are seen on the surface of any section made through 

 the organ. Each lobule (Fig. 134) consists of a number of hepatic 



FIG. 134. A lobule of the liver (pig), magnified, showing the hepatic cells 

 radiately arranged around the central intralobular vein, and the connective tissue 

 surrounding the lobule. (Scymonowicz.) 



cells supported by a close network of capillaries; and is separated 

 from neighboring lobules by connective tissue, larger blood-vessels, 

 and branches of the hepatic duct. The hepatic cells are the proper 

 tissue elements of the liver, all the rest being subsidiary arrange- 

 ments for their nutrition and protection. Each is polygonal, 

 nucleated and very granular, and has a diameter of about 0.025 

 millimeter (~ of an inch). In each lobule they are arranged in 

 rows or strings, which form a network, in the meshes of which the 

 blood-capillaries and bile-capillaries run. The blood carried in by 

 the portal vein (which has already circulated through the capil- 

 laries of the stomach, spleen, intestines and pancreas) is conveyed 

 to a fine vascular interlobular plexus around the liver-lobules, from 



