158 



PHYSIOLOGY AT THE FARM. 



ORGANS OF NUTRITION IN THE PIG. 



Teeth. Of the parts composing the mouth the teeth stand 

 first in order. The pig, like other mammals, has a set of milk 

 teeth which precede the permanent teeth. According to the 

 newest views on the subject of the teeth in mammals, those 

 are incisor teeth which are inserted in the intermaxillary or 

 premaxillary bone of the upper jaw, and in the corresponding 

 part of the lower jaw, whatever be their shape or size.* The 

 tooth which is situated in the maxillary bone, at or near the 

 suture with the premaxillary, is the " canine tooth," as is also 

 the tooth in the lower jaw, which, in opposing it, passes in 



Fig. 15 



VERTICAL SECTION OF THE HEAD OF THE PIG. 



a, Superior incisors ; b, superior lateral incisor ; c, inferior incisors ; d, upper canine or 



defence tusk ; e, inferior canine or defence tusk ; /, superior and inferior molars. 

 The course of the nerves may be distinctly traced in the figure. 



front of its crown when the mouth is shut. The other teeth 

 of the first set are " the deciduous molars ; " the teeth which 

 displace and succeed them vertically are the premolars. The 



* Owen. 



