292 



PHYSIOLOGY AND MORPHOLOGY OF ANIMALS. 



Our plan will be to take up each of these and carry 

 the process through the vertebrates ; and then in the 

 invertebrates to take up the whole process together in 

 each department. 



SECTION II. 

 Mouth Digesticm in Vertebrates. 



This includes the gathering (prehension), the mastica- 

 tion, and the insalivation of food. Prehension in man, 

 monkeys, and some other mammals is done by the hands 

 or paws. In some, as the elephant, by the snout, but 



in most vertebrates 

 directly by the 

 teeth. The object 

 of mastication is trit- 

 uration of the food 

 for more perfect 

 insalivation, and is 

 done by the teeth. 

 We shall have 

 much to say about 

 this process in con- 

 nection with the 

 comparative mor- 

 phology of the 

 teeth and physiol- 

 ogy of mouth di- 

 gestion. For the 

 present we dwell 

 and its effect on 



Fig. 178. — Lower jaw on right side and some 

 adjacent parts cut away so as to show the 

 salivary glands : p, parotid ; sm, submaxil- 

 lary ; si, sublingual. (After Cleland. ) 



only on the process of insalivation 

 digestion of the food. 



Salivary Glands. — There are three pairs of these, 

 viz., the parotids, p (Fig. 178), on the side of the face 

 just below and a little in front of the ear; the submax- 



