DIGESTION. 85 



The order of arrangement of the teeth is indicated by the 

 following dental formula: 



M- " s ~~ -M 

 B''' ~XB 



c/ 4 \c 

 I 



10. It is interesting, at this point, to notice the different 

 forms of teeth in different animals, and observe how ad- 

 mirably their teeth are suited to the respective kinds of 

 food upon which they subsist. In the carnivora, or flesh- 

 feeders, the teeth are sharp and pointed, enabling them 

 both to seize their prey, and tear it in pieces ; while the 

 herbivora, or vegetable- feeders, have broad, blunt teeth, 

 with rough crowns, suitable for grinding the tough grasses 

 and grains upon which they feed. Human teeth partake 

 of both forms ; some of them are sharp, and others are 

 blunt ; they are therefore well adapted for the mastication 

 of both flesh and vegetables. Hence we argue that, 

 although man may live exclusively upon either vegetable 

 or animal food, he should, when possible, choose a diet 

 made up of both varieties. 



11. Preservation of the Teeth. In order that the 

 teeth shall remain in a sound and serviceable condition, 

 some care is of course requisite. In the first place, they 

 require frequent cleansing ; for every time we take food, 

 some particles of it remain in the mouth ; and these, on 

 account of the heat and moisture present, soon begin to 

 putrefy. This not only renders the breath very offensive, 

 but promotes decay of the teeth. 



10. Different forms of teeth ? Human teeth ? The inference ? 



1 1 . Cleaning of teeth ? Effects of not cleaning ? 



