ORGANS OF THE BODY. 505 



named by Kiernan, on account of their position, the vence intralobulares, 

 by Gerlach vence centrales. On their exit from the lobules these vessels 

 join together to form larger trunks. The latter are intimately connected 

 with the parenchyma of the organ, so that they remain gaping even 

 when emptied. From the fact that the veins of the liver do not possess 

 valves, the whole hepatic circulation may be just as easily injected from 

 them as from the portal vessels. 



264. 



So far we have only discussed those points of structural arrangement of 

 the liver which are easily recognisable, and may be therefore regarded as 

 permanent additions to histological knowledge. 



Far different is it now, however, when we come to deal with questions 

 as to the nature of the sustentacular substance of the interior of the 

 lobules, with the relations of the veins to the finest biliary ducts, as well 

 as the disposal of the radicles of the lymphatic system in the parenchyma 

 of the gland. 



From the fact that the two networks that formed by the intersection 

 of bands of hepatic cells and that of the circulation are closely inter- 

 woven one with another, many suppose that the hepatic cells are simply 

 entangled in the meshes of the capillary network. 



Nevertheless, if very fine sections of a properly hardened liver be care- 

 fully brushed with a camel's hair 

 pencil, there remains, after removal 

 of the hepatic cells, an exquisitely 

 delicate reticulated framework, com- 

 posed of homogeneous membranous 

 bands, which separate the rows of 

 gland cells and blood stream from 

 one another. In this network may 

 be seen, in the first place, the nuclei 

 of the capillaries, and then, small 

 Isolated nuclei, which present them- 

 selves in a shrunken condition in 



t.~ KAO\ Fi - 502. Sustentacular tissue from the liver of 



(ng. OU^;. the in f ant . 0) homogeneous membrane with 



In the liver of the infant. Or nuclei; 6, filiform folds in the former ; c, isolated 

 , ,1 i , ,1 f , hepatic cells, remaining after brushing. 



foetus, m the later months ot utero- 



gestation, this fine transparent membranous structure may be seen at 

 certain points to be double. One of its layers corresponds to the walls of 

 the capillaries, and in some instances has been resolved into those vascular 

 cells so well known (p. 363) (Eberth). Its other lamina, on the other hand, 

 invests the bands of hepatic cells as they intersect each other. 



From this it would appear to be beyond doubt that a thin homogeneous 

 layer of sustentacular connective-substance envelopes the various rows of 

 hepatic cells. This layer is often of the most extreme delicacy, but may 

 be seen with comparative ease to be continuous at the periphery of each 

 lobule with the interlobular connective-tissue. 



Here then we hav the long sought for membrana propria of the 

 hepatic cells presenting itself. To it belongs indubitably the second and 

 smaller series of nuclear formations, which appear at an early period in 

 greater abundance, as a system of connective-tissue corpuscles, frequently 

 exhibiting distinct cell bodies. 



While at first these two membranes, namely, the sustentacular connec- 



