58 ANIMAL INTELLIGENCE 



periods of hibernation followed by intervals of con- 

 sciousness, during which they feed; whether they 

 remain in a condition of partial torpor, with slow- 

 ing of all the vital processes, and yet not in absolute 

 insensibility and with cessation of respiration, etc. 

 all these questions seem to be as yet wholly un- 

 decided. 



It has long been known that many cold-blooded 

 animals hibernate and, under altered conditions, 

 aestivate; it is further believed that among warm- 

 blooded animals, besides bats, many rodents, and some 

 allied animals hibernate. But when the matter is 

 looked into carefully it is found that the term " hiber- 

 nation " has been used in a loose and very plastic sense 

 by different authors. It is highly desirable, therefore, 

 that writers should state exactly to what extent the 

 animal they describe as "torpid," "hibernating," or 

 " in winter-sleep," deviates functionally from the 

 normal; also, that the exact time of the observations 

 be recorded. There is a certain amount of evidence 

 that even birds, representing the highest type of 

 activity, may possibly hibernate, and that many 

 animals, not usually thus affected, may become so 

 under exceptional circumstances indeed that man 

 himself, owing to peculiar states of the nervous system, 

 may pass into a condition (" trance ") having much in 

 common with the hibernation of lower animals. I 

 think it is very probable that, when the matter has 

 been fully investigated, all degrees of cessation of 

 functional activity will be found represented, from the 

 normal daily sleep of man and other animals to the 

 lowest degree of activity consistent with the actual 

 maintenance of life. The Flying Squirrel is nocturnal 

 in habits and exceedingly active, even in confinement, 

 as Prof. Perkins (loc. cit.) has shown ; but during the 

 day-time it seems not to be correspondingly quick in 



