PHYSIOLOGICAL ANATOMY OF THE LITER. 237 



by branches of the duct, much less numerous and smaller, 

 measuring only ^soo ^ an mcn ? an d some, even, have been 

 measured that are not more than 3^ of an inch in diam- 

 eter. 1 



Lobular Vessels. In the interlobular plexus, the ramifi- 

 cations of the hepatic artery are lost, and this can no longer 

 be traced as a distinct vessel. One of the peculiarities of its 

 arrangement, as we have seen, is that the artery 'does not 

 empty into the radicles of the efferent vein, but joins the 

 portal vessels as they are about to be distributed in a true 

 capillary plexus in the substance of the lobules. In the lob- 

 ules themselves, consequently, we have only to study the 

 arrangement of the portal plexus, with the mode of origin of 

 the hepatic veins and the relations of the hepatic duct. 



The arrangement of the lobular plexus of blood-vessels 

 is very simple. From the interlobular veins, a number of 

 branches (eight to ten) are given off and penetrate the lobule. 

 As the interlobular vessels are situated between different 

 lobules, each one sends branches into two and sometimes 

 three of these lobules ; so that, as far as vascular supply is 

 concerned, these divisions of the liver are never absolutely 

 distinct. 



After passing from the interlobular plexus into the 

 lobules, the vessels immediately break up into a close net- 

 work of capillaries, from -g-^ to ^Vrr f an i ncn * n diame- 

 ter, 3 which occupy the lobules with a true plexus. These 

 vessels are very numerous; and when they are fully dis- 

 tended by artificial injection, their diameter is greater than 

 that of the intervascular spaces. It must be remembered, 

 however, that in the study of the liver by minute injections, 

 as in other parts, the vessels probably are distended so that 

 they occupy more space than they ever do under the physio- 

 logical conditions of the circulation. The blood, having been 



1 BEALE, On some Points in the Anatomy of the, Liver of Man and Vertebrate 

 Animals, London, 1856, p. 58. 



2 KOLLIKER, op. tit., 1867, S. 442. 



