LIVER 



347 



latter with the stomach. Both ontogenetically and phylogenetically 

 the liver is an older organ than the pancreas, which is developed 

 from the same endodermal matrix. 



In Amphioxus a simple sac-like caecum (Fig. 258) arises from 

 the intestine just behind the pharynx, and this " hepatic caecum " 

 may probably be looked upon as the rudiment of a liver. 



KO 



El 



FIG. 255. VISCERA OF Lacerta agilis. 



Bf, urinary bladder ; Ci, postcaval ; ED, large intestine ; GB, gall-bladder ; 

 H, heart ; L, liver ; Lg, Lg l , the two lungs ; Jlf , stomach ; MD, small 

 intestine ; Oe, oesophagus ; Pn, pancreas ; Tr, trachea. 



In the Anamnia, the liver is usually relatively larger than in 

 the Amniota, and Carnivores generally possess a larger liver than 

 Herbivores. In Myxinoids it departs least from the original tubular 

 type, from which that of the Amphibia and Reptilia, and more especi- 

 ally the Mammalia, diverges most widely. All these modifications 

 in its structure are traceable, in the first instance, to the vascular 



