TEETH OF ANIMALS. 257 



X. 



OF THE TEETH OF ANIMALS THEIR MECHANICAL 



PROVISIONS. 



The teeth form a subject of much higher inter- 

 est than will at first be readily imagined. There 

 is no part of an animal body where "contrivance" 

 is more distinctly demonstrated, or in which a re- 

 semblance is more obvious between the mechan- 

 ism of engines and the provisions in the animal 

 mechanism. Suppose an instrument were to be 

 ingeniously contrived to cut like an adze, or to di- 

 vide like a pair of shears, or to grind like a mill- 

 stone, or to hold like a mouse-trap,* or to tear, — 

 what, after a period of working, would be the con- 

 dition of these machines ? Would not the edge be 

 blunted — the sharp points become rounded — 

 the grinding surfaces smoothed? — and would not 

 the teeth of the machine be driven deep into the 

 sockets, and so render it wholly useless? But 

 nothing of this kind takes place in the teeth of ani- 

 mals. They are perfect for their purpose, and, if 

 duly exercised, last the natural term of life, how- 

 ever the period of natural decay may vary in dif- 

 ferent animals. 



* As in the gullet of fishes. 

 23* 



