THE LIVER. 129 



ramuscules. These veins, which in Man are 0*012 — 0-03'" in 

 diameter, are best studied in some animal whose liver breaks 

 up into isolated lobules, as the Pig; after which Kiernan has 

 given his somewhat diagrammatic figure. If we here open a 

 small branch of the hepatic vein, polygonal arese are descried 

 through the walls of the vessel — the outlines of those surfaces 

 of the lobules which are turned towards the vein (fig. 218). 



A minute vein which, in the centre of each of these surfaces, 

 termed by Kiernan " bases of the lobules/' opens directly into 

 the larger vessel leads, if we trace it in the opposite direc- 

 tion, into the interior of a lobule, where it arises from the 

 capillary network; but under no circumstances is it continued 

 into a second or third lobule. In this way only a single vein, 

 which may thence be called vena intra-lobularis, arises in each 

 lobule. The vessels into which these veins directly open are 

 called by Kiernan sublobulares, because they ran along the 

 basal surfaces of the lobules. They are sometimes large, at- 

 taining as much as 1 — 2'" in the Pig, and then lie in canals 

 which are surrounded by the basal surfaces of a certain number 

 of lobules ; at other times they are smaller, down to ~" t in 

 which case they only pass between the lobules. The sublobular 

 veins unite into larger veins, which continue to receive, directly, 

 but few or no other intra-lobular veins and thence, are only 

 partly or not at all bounded by the basal surfaces of the lobules, 

 but only by their lateral or apical surfaces (•" capsular surfaces/ 

 Kiernan). Such veins, when they are smaller, still receive sub- 

 lobular veins from the groups of lobules which immediately 

 surround them ; or, lastly, only larger veins, which have the 

 same relations as themselves. 



The intra-lobular veins are very simply arranged. Each of 

 them penetrates directly into the axis of an hepatic islet, or 

 lobule, dividing in the middle into two or three principal 

 branches, which frequently again subdivide. The capillaries 

 open, not merely into the terminations of these veins, but also 

 into their trunks throughout their course; indeed, according 

 to Theile, the origins of the sublobular veins also receive capil- 

 laries. In all those hepatic lobules or islets whose apices are 

 turned either towards the surface of the liver, or to a large 

 vascular trunk, the interlobular veins extend nearly to their 

 extremities; whilst in others they stop more nearly in the 



n. 9 



