544 SPECIAL HISTOLOGY. 



again subdivide. The capillaries open, not merely into the terminations 

 of these veins, but also into their trunks throughout their course ; in- 

 deed, according to Theile, the origins of the sublobular veins also re- 

 ceive capillaries. In all those hepatic lobules or islets whose apices are 

 turned either towards the surface of the liver, or to a laro-e vascular 

 trunk, the interlobular veins extend nearly to their extremities ; whilst 

 in others they stop more nearly in the middle, so that they are always 

 about half the diameter of the lobules distant from the nearest inter- 

 lobular veins of the vena iportce. 



The hepatic artery^ for the most part, accompanies the portal vein and 

 the biliary canals, is enclosed with the latter in Glisson's capsule, and, 

 in its principal ramifications, presents precisely the same relations as 

 the portal vein. It is finally distributed upon the vessels and biliary 

 ducts, in Glisson's capsule, in the fibrous and serous coats of the liver, 

 and in the hepatic islets, whence its branches are denominated rami 

 vasculares, capsulares, and lobulares. 



1. Rami vasculares. — As it divides, in company with the vena jjortce^ 

 the hepatic artery gives off numerous small branches, almost at right 

 angles, which form a plexus in Glisson's capsule, from which some lobu- 

 lar branches for the parietes of the portal canal arise, on the side oppo- 

 site to the arterial trunks ; while many twigs proceed to the walls of the 

 portal vein, the larger branches of the artery itself, the hepatic veins, 

 Glisson's capsule and the biliary ducts. The distribution of the vessels 

 is particularly remarkable in the latter canals, so that, in a good injec- 

 tion, they appear almost as red as the arteries themselves. 



A moderately close capillary network exists around all these parts, 

 even the glands of the biliary ducts, whence the' vence vasculares arise 

 and open, as Ferrein discovered and as all the moderns since Kiernan 

 have agreed, not into the hepatic vein, but into small portal twigs, as 

 these are leaving the larger branches in Glisson's capsule, and are there- 

 fore to be regarded as internal, or hejjatic radicles of the portal vein. 

 From this cause the portal vein may be partially injected from the 

 hepatic artery and conversely. Again, in injecting the hepatic artery 

 and the portal vein, the vascular network in question may be filled from 

 both sides ; while it is not possible directly to force injection from the 

 hepatic vein into them. 



2. Rami capsulares. — -Independently of a few branches given off by 

 the artery, before its entrance into the liver, to the fossa ductus venosi, 

 to the ligamentum teres and suspensorium, all the arterial twigs of the 

 coats of the liver are the terminal prolongations of certain arteries which 

 penetrate the liver and appear in diff'erent parts of its surface between 

 the hepatic islets. At the points of exit, and even before reaching them, 

 these vessels, which have a diameter in the adult of 1-30-1-20 of a line, 

 in children as much as 1-5 of a line, break up into 3-5 radiated subordi- 



