BACKBONED ANIMALS. 



Hedgehog (Erinaceid<K)*\3s now come to the 

 true hedgehogs (Fig. 339), that are not found in the 

 western hemisphere, and are characterized by a thick 



FIG. 339. A group of insect-eaters : i, common shrei 

 3, mole ; 4, bat. 



2, hedgehog; 



growth of sharp, spinous bristles upon the back, that, 

 when the animal rolls itself into a ball, form a perfect 

 protection. 



VALUE. Skin and spines. 



* The nest is generally underground, and carefully made, and 

 here the adults, as a rule, pass the cold months in a state of hiber- 

 nation a sleep so deep that no outward sign of breathing can be de- 

 tected. In Dr. Hall's experiments with a hibernating animal suddenly 

 decapitated, the heart continued to beat for a long time, as if possessed 

 with an independent life. In another, where the brain and entire 

 spinal cord were removed, the heart continued to beat for two hours, 

 as if nothing had happened, and twelve hours after would contract 

 when touched. 



