332 



COMPARATIVE ZOOLOGY 



secreting cells. It is of variable shape, but usually two, 

 three, or five lobed, and is centrally situated in mam- 

 mals, just below the diaphragm. In most vertebrates, 

 there is an appendage to the liver called the gall bladder, 

 which is simply a reservoir for the bile. 



VP4 



FIG. 289. Liver of the Dog: F, F, liver; D, duodenum and intestines; P, pancreas; r> 

 spleen; e, stomach, f, rectum; R, right kidney; B, gall bladder; ch, cystic duct; 

 F', lobe of liver dissected to show distribution of portal vein, VP, and hepatic vein, 

 vh ; */, diaphragm; VC, venacava; C, heart. 



The so-called liver of invertebrates is more like the 

 pancreas of vertebrates in function, as its secretion 

 digests starches and albuminoids. The liver of verte- 

 brates is both a secretory and an excretory organ. The 

 bile performs an important, although ill-understood, func- 

 tion in digestion, and also contains some waste products. 



