2io GNAWING ANIMALS 



sharp edge like that of a chisel, whose cutting edge consists 

 of a plate of hard steel backed by softer iron. 



The incisors, set exactly opposite each other, need 

 continual use to preserve their cutting edge. As fast as 

 the teeth are worn down fresh material is supplied from 

 the hollowed base. The growth of the incisors in the 

 Rodents is so rapid that the animals must continually gnaw 

 if they are to exist in comfort, or in fact to exist at all, for 

 they would grow to such a size that it would be impossible 

 to open and close the mouth. Hence, when a Rodent is 

 not employing its teeth on food, it apparently engages them 

 in the wanton destruction of some hard substance altogether 



useless for food ; or failing 

 that, it works its jaws in- 

 cessantly from side to side, 

 grinding the teeth against 

 each other, ever seeking to 

 prevent the possibility of 

 overgrowth. 



The illustration of the 

 rabbit's head shows what 

 happens when the animal 

 breaks an upper incisor of 

 the right side and a lower 



HEAD OF A RABBIT. inCiSOF f the left Side The 



Showing abnormal growth of incisor teeth. Unbroken teeth grOW UI1- 



checked, following the curve 



of their sockets, and assuming the remarkable forms which 

 are there figured. 



The Rodentia are for the most part vegetable feeders ; 

 some are really omnivorous ; and the majority of them 

 are particularly destructive to grain, whether in the crop 

 or garner. The fur of some of the species is of considerable 

 commercial importance ; and there are few of them whose 

 flesh is not fit for food, though in several cases its odour 

 leaves something to be desired. In England hares and 

 rabbits are the only Rodents which are usually eaten, but 

 mankind is as omnivorous as any of the beasts of the field, 

 and in one region certain animal food is accounted a 

 delicacy, which in another is viewed with loathing. 



