

110 ANIMAL FUNCTIONS. 



MASTICATION. 



This word comes from the Latin mastico, which signi- 

 fies to chew. Chewing is one of the natural functions of 

 animals, the object of which is, to divide the food into 

 minute pieces, and thus to prepare it for passing through 

 the esophagus into the stomach, to undergo the process 

 of digestion. 



While the food is masticating, it is at the same time 

 intermixing with a fluid called saliva, which is prepared 

 by glands situated around the mouth, and into the cavi- 

 ty of which it is poured through small ducts, coming 

 from the glands by which it is secreted. The action of 

 the muscles concerned in mastication, serve to stimulate 

 these glands ; in consequence of which they afford a 

 larger quantity of the fluid at the time when it is most 

 necessary. The same action also facilitates the passage 

 of the saliva into the mouth. 



If the mouth had been constructed without this pro- 

 vision for moistening the food, it is obvious that dry, ab- 

 sorbent substances, could not have been swallowed ; 

 since it is absolutely necessary, as our experience teach- 

 es, to reduce such substances to a soft pulpy mass, be- 

 fore they can be forced through the esophagus. 



There is a great difference in the form, structure, po- 

 sition, and number of the teeth of different animals; all 

 of which bear a direct and intimate relation to the kind 

 of food on which they subsist. Thus the teeth of the Li- 

 on, the Wolf, and the Cat, are constructed for tearing the 

 flesh of animals ; while those of the Cow, Sheep, and 

 Deer, are made to crop the tender herbs. 



The teeth of the Lion could no better perform the of- 

 fice assigned to those of the Cow, than the Cow could 

 rend the skin, and divide the muscles of a living victim, 

 in the manner of the Lion. 



Teeth of Man. In the human subject the number of 



What is meant by mastication 7 Is chewing a vital, or a natural 

 function 1 What is the use of mastication 7 How is the food moisten- 

 ed during mastication 7 What is said of the form of the teeth, in rela- 

 ion to the kind of food on which the animal lives 7 



