DIGESTION AND FOOD. 11 



render some assistance in the work of digestion. All these 

 organs together form the digestive apparatus, which is com- 

 plete and perfect in itself; nothing is wanting for the work, 

 and there is nothing unnecessary. Each one of these organs, 

 or parts of organs, has a separate and distinct part to perform 

 in the work of converting food into the nutriment of the blood. 



7. The mouth is the first and only visible organ of digestion, 

 and first receives the food from our hands and our tables. It 

 is composed of several parts, all of which are employed in 

 the preparatory work of digestion. The lips and the cheeks 

 form the outward walls of the mouth, and retain the food 

 after it is received. The teeth serve to divide and break 

 down the morsel to a fineness suitable to the stomach. The 

 tongue rolls the morsel about, and keeps it in its place be- 

 tween the teeth, while it is undergoing the process of masti- 

 cation or chewing, and afterwards helps t to propel it back- 

 ward in the act of swallowing. 



8. The teeth differ in various animals, according to the food 

 which they eat. The carnivorous or flesh-eating animals 

 have teeth fined for seizing upon their prey, and for cutting 

 up fiesh. Hence they have sharp cutting or front teeth ; 

 arid long, sharp and pointed canine or stomach and eye teeth ; 

 and grinders, with high and sharpened points, by which they 

 chew or* masticate their fleshy food with facility. 



9. The vegetable-eating animals have short, blunt, arid 

 strong front or incisor teeth, by which they break off their 

 food, either grass or foliage. As they seize no prey, they 

 have no use for the sharp canine or stomach and eye teeth ; 

 therefore these teeth are very small, and in some scarcely 

 seen ; but their molar or grinding teeth are very large, brocd, 

 and flat. Their surface is covered with slightly-raised lines, 

 to enable them to grind down their food, which requires more 

 crushing than cutting. 



10. Man is neither herbivorous nor carnivorous exclu- 

 sively, but is either or both, as occasion requires. Com- 

 monly he is both. His food, for the most part, is a mixture 

 of vegetables and flesh. He is therefore fitted with a set of 



