RODENTS : 

 ANIMALS THAT GNAW 



The Rodents are animals that gnaw, and in con- 

 sequence we find they possess teeth eminently suited 

 for that purpose. 



A Rodent or gnawing animal can at once be 

 recognised by its front or incisor teeth, and the 

 absence of canine teeth. The incisors are large and 

 curved. If the points are examined they will be 

 found to be chisel-like, viz. bevelled off on the 

 inner edge. The reason is that the outer face of 

 the tooth is covered with hard enamel, while the 

 rest of the tooth consists of soft ivory, consequently 

 when used the soft inner pbrtion wears away, leaving 

 a sharp cutting edge of enamel. The idea of a 

 carpenter's chisel originated from the gnawing teeth 

 of Rodent animals. The thin layer of steel which 

 constitutes the cutting edge of a chisel corresponds 

 with the enamel of a Rodent's tooth, while the 

 thicker portion of the chisel, which is designed to 

 give support to the thin layer of hard steel, is 

 similar to the ivory portion of a Rodent's incisor 

 tooth. 



These teeth, which are so perfectly adapted for 

 gnawing, are remarkable in another way. They 



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