SOME INTERNAL STRUCTURES 65 



that the stomach is primarily divisible into two parts ; 

 but that is a universal character, and is indeed seen 

 in other vertebrates, for example, in birds, sharks, etc. 

 From such a simply-divided stomach as is seen in 

 various Rodents, and in other types of mammals, both 

 the Cetacean and the Ruminant stomach may have 

 arisen, and the resemblances between them will in 

 this case be an example of that frequent phenomenon 

 in the organic world, convergence. 



To account for this likeness by convergence is 

 a matter of interesting inquiry. The other com- 

 plicated stomachs which are found in mammals are 

 invariably associated with a vegetarian diet. The 

 Sloth, the Oxen and Sheep, and the Manatee and 

 Dugong are all vegetable feeders. The whales are 

 most distinctly carnivorous animals. 



It has been suggested, however, that whales 

 ruminate like oxen. This process (in the Rumi- 

 nantia) consists of the following series of acts. The 

 animal bites off and swallows an immense amount 

 of herbage, leaves, etc., and swallows them hastily; 

 the mass thus swallowed is permeated by the saliva 

 and is then returned to the mouth, where it is 

 thoroughly masticated at leisure, and re-swallowed to 

 be properly digested. It is held that the Ruminantia, 

 being as a rule timid creatures, who have to be on 

 their guard against their numerous carnivorous foes, 

 gain an advantage by this apparently complicated 

 and even disadvantageously complicated act. They 

 can lay in their store of food hastily and with rapidity, 

 and then at a more convenient season, when danger 



