THE LIVER 209 



cava, a, is seen to traverse a notch in the hinder edge of 

 the liver as it passes from the abdomen to the thorax. 

 At h the trunk of the vena portae is observed dividing 

 into the chief branches which enter into, and ramify 

 through, the substance of the organ. At d, the hepatic 

 artery, coming ahnost directly from the aorta, similarly 

 divides, enters the liver, and ramifies through it. At c is 

 the single trunk of the duct, called the hepatic duct, 

 which conveys away the bile brought to it by its right 

 and left branches from the liver. Opening into the 

 hepatic duct is seen the duct of a large oval sac, I, the 

 gall-bladder. The duct is smaller than the artery, and 

 the artery than the portal vein. 



The liver consists of two chief lobes of which the right 

 is much larger than tlie left." Externally the lobes are 

 covered with a layer of connective tissue forming its 

 capsule, and a quantity of connective tissue forms a thick 

 sheath for the vena portfe, hepatic artery and bile-duct, 

 as these plunge into the liver. This sheath accompanies 

 the vessels as they ramify into the liver and finally forms 

 a number of partitions, continuous with the capsule on the 

 outside, which divide each lobe into a very large number 

 of smaller divisions called lobules. These partitions 

 are much thicker and more conspicuous in some animals, 

 such as the pig, than they are in others, such as the 

 rabbit ; in the former it is very easy to see on the outside 

 of the liver the outlines of the lobules; in the latter it is not 

 so easy. The lobules are about y\j of an inch in diameter 

 and are thus visible to the naked eye. Each lobule is 

 made up of a mass of cells, the hepatic cells, which lie 

 in the meshes of a close-set network of blood capillaries. 

 These capillaries radiate from a small blood-vessel which 

 runs down the centre of each lobule towards its base ; 

 this central blood-vessel is called the intralobular 

 vein (Fig. 64, A, H.V.), and, passing out of the lobule 

 at its l)ase, runs into a branch of that great vein, the 

 hepatic vein, wl^ich carries the blood away from the 



p 



