498 



THE LIVEE. 



[en. xxxni. 



through the substance of the liver, they are contained in small 

 channels called portal canals, their immediate investment being a 

 sheath of areolar tissue continuous with Glisson's capsule. 



To take the distribution of the portal vein first : In its 

 course through the liver this vessel gives off small branches 

 which divide and subdivide between the lobules surrounding them 

 and limiting them, and from this circumstance called mtfer-lobular 

 veins. From these vessels a dense capillary network is prolonged 

 into the substance of the lobule, and this network converges to a 

 single small vein, occupying the centre of the lobule, and hence 



Fig. 409. Hepatic cells and bile capillaries* from the liver of a child three months old. 

 Both figures represent fragments of a section carried through the periphery of a lobule. 

 The red corpuscles of the blood are recognised by their circular contour ; vp, corresponds 

 to an interlobular vein in immediate proximity with which are the epithelial cells of 

 the biliary ducts, to which, at the lower part of the figures, the much larger hepatic 

 cells suddenly succeed. (E. Hering.) 



called m^ra-lobular. This arrangement is well seen in fig. 

 406, which represents a section of a small piece of an injected 

 liver. 



The small mtfra-lobular veins discharge their contents into 

 veins called s^Wobular (h h h, fig. 407) ; while these again, by 

 their union, form the main branches of the hepatic veins, which 

 leave the posterior border of the liver to end by two or three 

 principal trunks in the inferior vena cava, just before its passage 

 through the diaphragm. The sub-lobular and hepatic, veins, 

 unlike the portal vein and its companions, have little or no 

 areolar tissue around them, and their coats are very thin ; they 

 form little more than mere channels in the liver substance which 

 closely surrounds them. 



The hepatic artery, the chief function of which is to distribute 

 "blood for nutrition to Glisson's capsule, the walls of the ducts and 

 blood-vessels, and other parts of the liver, is distributed in a very 



