KIERNAN'S RESEARCHES. 519 



The interlobular branches proceed from the vaginal biliary plexus 

 where it exists, and directly from the hepatic duct on that side of 

 the smaller canals against which the duct is placed. They enter 

 the interlobular spaces, and ramify upon the capsular surface of the 

 lobules, in the interlobular fissures, where they communicate freely 

 with each other. The lobular ducts are derived chiefly from the 

 interlobular ; but to those lobules forming the walls of the portal 

 canals, they pass directly from the vaginal plexus. They enter the 

 lobule and form a plexus in its interior, the lobular biliary plexus, 

 which constitutes the principal part of the substance of the lobule. 

 The ducts terminate either in loops or in cascal extremities. 



The coats of the ducts are very vascular, and supplied with a 

 number of mucous follicles, which are distributed irregularly in the 

 larger, but are arranged in two parallel longitudinal rows in the 

 smaller ducts. 



The Hepatic artery enters the liver with the portal vein and 

 hepatic duct, and ramifies with those vessels through the portal 

 canals. Its branches are the vaginal, interlobular, and lobular. The 

 vaginal branches, like those of the portal vein and hepatic duct, 

 form a vaginal plexus, which exists throughout the whole extent of 

 the portal canals, with the exception of that side of the smaller 

 canals which corresponds with the artery. The interlobular branches, 

 arising from the vaginal plexus and from the parietal side of the 

 artery in the smaller canals, ramify through the interlobular fis- 

 sures, and are principally distributed to the coats of the interlobular 

 ducts. 



" From the superficial interlobular fissures small arteries emerge, 

 and ramify in the proper capsule, on the convex and concave surface 

 of the liver, and in the ligaments. These are the capsular arteries" 

 Where the capsule is well developed, " these vessels cover the sur- 

 faces of the liver with a beautiful plexus," and " anastomose with 

 branches of the phrenic, internal mammary, and supra-renal arte- 

 ries," and with the epigastric. 



The Lobular branches, extremely minute and few in number, are 

 the nutrient vessels of the lobules, and terminate in the lobular 

 venous plexus. 



All the venous blood resulting from the distribution of the hepatic 

 artery, even that from the vasa vasorum of the hepatic veins, is 

 returned into the portal vein. 



The Hepatic veins commence in the substance of each lobule by 

 minute venules, which receive the blood from the lobular venous 

 plexus, and converge to form the intralobular vein. The intralobular 

 vein passes through the central axis of the lobule, and through the 

 middle of its base, to terminate in a sublobular vein ; and the union 

 of the sublobular veins constitutes the hepatic trunks, which termi- 

 nate in the inferior vena cava. The hepatic venous system consists, 

 therefore, of three sets of vessels ; intralobular veins, sublobular 

 veins, and hepatic trunks. 



