69 
stomach and the right and dorsal surface of the spleen. 
It is a large thin-walled sac about one inch in diameter 
in large plaice. It is not imbedded in the liver in any 
way, and is attached to the latter organ by means of the 
bile duct only. Its posterior wall is thickened by a little 
nodular swelling. Its efferent duct leaves the anterior 
and ventral surface, turns back and runs on the internal 
surface of the right hepatic lobe partially imbedded in the 
tissue of the latter. Three groups of hepatic ducts enter 
it: one of these is situated near the proximal end of the 
duct, the other two are placed about midway on its course 
and enter it from opposite sides. Each is a group of three 
or four ducts. The eystic duct is the portion of the whole 
duct between the gall bladder and the opening of the first 
hepatic duct, the remaining portion is the common bile 
duct. ‘The walls of the bile duct are slightly iridescent, 
the distal extremity is thick and swollen, but encloses a 
very narrow lumen. It enters the duodenum between the 
paired pyloric ceca. Its opening into the duodenum is 
extremely small, and is very difficult to observe from the 
interior of the latter. The bile is a transparent slightly 
greenish fluid. The liver in the plaice, as in all other 
vertebrates, has a double blood supply, receiving blood 
from the veins of the intestine by the hepatic portal 
channels and from the dorsal aorta via the cceliaco-mesen- 
teric artery by the very small hepatic artery (A. hep. fig. 
22). Of these sources the hepatic portal system of veins 
is by far the most important, and the system of intra- 
hepatic vessels containing venous blood is exceedingly 
striking in sections of the organ. The liver is essentially 
a tubular gland, but the hepatic tissue is disposed in 
strings of cells in which as a rule the lumen or bile capil- 
lary is only apparent from the radiate arrangement of the 
hepatic cells in transverse section of the strings. Within 
