HYBERNATION. 127 



awakes from a natural slumber, and the system 

 suffers no shock. Animals which hybernate 

 at a certain period of the year, in obedience to 

 a protective law, will not hybernate if exposed 

 to cold at another season ; and if the cold be 

 intense they will perish, a fact proved by the 

 experiments of Mangili. 



