102 HEPATIC DUCT. 



It has been asserted by Ferrein, Autenreith, Andral and 

 others, that there are two substances in the liver, a cortical 

 and medullary, or red and yellow ; the former of which was 

 exterior and the latter central, in each lobule. This has been 

 denied by Cruveilhier and Miiller; and Kiernan has shown 

 that this difference in color, depends upon the separate con- 

 gestion of one of the different system of vessels, for such is the 

 great vascularity of the livef.that it is usual after death to find 

 one or other in a state of congestion. By injecting with moder- 

 ate force a colored fluid into the hepatic veins, he found he could 

 color red, even in the healthiest liver, the central parts of the 

 lobules ; by using more force he could color the whole substance 

 of the lobule, in consequence of the fluid passing then into the 

 portal branches. By injecting the portal system in a similar 

 manner, the outer part of the lobule was the first colored. The 

 yellow color of these acini or lobules is owing, according to 

 Cruveilhier, to a congestion of bile in the radicles of the biliary 

 ducts. The opinions of this anatomist coincide in the main in 

 regard to the structure of the acini, with those of Mr. Kiernan. 

 He believes, however, that the termination or rather origin of the 

 branches of the biliary duct is from the centre of each acinus, 

 and that immediately around this is a vascular circle formed 

 by the radicles of the hepatic intralobular vein, while the portal 

 system forms a circle extrinsic to the whole. He also believes 

 that there is a part of the outer surface of each lobule, which 

 is uninjectable, spongy and porous, and serves the part of a 

 filter.* 



The Biliary or Hepatic Duct, is formed of very minute 

 vessels, which originate in the acini above described : these 

 unite together like veins until they form considerable branches, 

 which finally compose the great ramifications of the biliary 

 duct. This duct is very strong and firm, and on its internal 

 surface are the orifices of many mucous follicles or ducts. It 

 passes from the transverse fissure of the liver, with the hepatic 

 artery, as before described, and at the distance of an inch and 

 a half or two inches from the fissure, it unites with a duct from 

 * Anat. Descript. T. ii. p. 575. 



