CHAPTER XXVII. 



THE TEETH. 



1. (is the teeth are the only bones in the human frame 

 whicfc. are exposed to the immediate action of foreign bodies, 

 they mfrrit distinct and special consideration in this treatise 

 on the General Physiology of man) /^The most remarkable 

 fact in their history is, that unlike the other bones, the teeth 

 which make their appearance in infancy, are removed at the 

 age of seven or thereabouts, and another set come forward 

 to supply their places.) 



2. /The first set called temporary teeth, are just twenty in 

 number, ten in each jaw. The two front teeth above and be- 

 low, are known as central incisors, because they serve to cut 

 the food. The teeth adjoining these are denominated lateral 

 incisors, next to which come the canine or dog teeth, of 

 which those in the upper jaw are called eye teeth. Back of 

 these at either extremity of each dental arch are two larger 

 teeth known as grinders from the fact that they operate like 

 mill-stones, in reducing the food to very minute particles in 

 preparation for quick and easy digestion^ 



3., 'The second or permanent set has twelve additional 

 teeth, six above and six below, making thirty-two in all. 

 The two next back of each eye tooth, are styled bicuspids, 

 because they terminate in two points ; and the four extreme 

 grinders are sometimes called wisdom teeth, because they do 

 not generally appear until the individual arrives at mature 

 age. Thus, there are twelve grinders or molar teeth in the 

 second set instead of eight as in the first set ; and there are 

 eight bicuspids which are not found among the temporary 

 teeth at all J 



4. feach tooth consists of two distinct parts, called the 

 crown and root / the former being that portion which pro- 



