178 DE- T. WESLEY MILLS ON 



intervais of consciousness, during which they feed; whether Ihey remain in a condition 

 of partial torpor, with slowing of all the vital processes, and yet not in absolute insensi- 

 bility and with cessation of respiration, etc. — all these questions seem to be as yet wholly 

 undecided. 



It has long been known that many cold-blooded animals hibernate and, under altered 

 conditions, sestivate; 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 " hibernation " has been used in a loose and very 

 plastic sense by diflerent 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 

 obscrA^ations be recorded. There is a certain amount of evidence that even birds, repre- 

 senting 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 ") 

 haAnng 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 shewn ; but during the day time it seems not to be corre- 

 spondingly quick — in a condition, in fact, resembling somewhat that of a hibernating 

 animal. The " diurnal hibernation " of the bat is not to be forgotten. I noticed that my 

 .Chipmunk invariably, after feeding, tucked his head down and assumed a more or less ball- 

 like form highly suggestive of a tendency to hibernation. 



There are many questions that arise in connection with this subject, one of which 

 bears directly on the subject of comparative psychology : — How and to what extent is the 

 intelligence of animals influenced by hibernation ? It may be considered pretty clear 

 that both the Ground Squirrel and the Flying Squirrel hibernate, and these are certainly 

 among the lowest — perhaps, are actually the lowest — in intelligence of the whole tribe. 

 We know that struggle among higher animals develops mental adaptation and other 

 forms of intelligence, and it is rational to suppose that those species of squirrels that do 

 not hibernate throughout the winter, bu.t endeavor to prevail over their surroundings, as 

 well as to adapt themselves to them, should be more intelligent than those spending a 

 large portion of each year in inactivity. 



My Chipmunk, during its captivity, under certain circumstances, kept to his original 

 habits, e.g., when a single nut was given him he would eat it immediately, but if several 

 were presented at once, he would hide them one by one in a corner of his cage or, if 

 sufiiciently small, pack them away in his cheek-pouches. He did the same with cereal 

 grains. When cotton wool or web-like material was placed in the cage, he manipulated 

 it a good deal, but finally made a bed of it, in which he buried himself out of sight. 



Within the last ten years, attention has been called to " singing " in certain rodents, 

 especially mice ; but from numerous references in the literature it appears that " singing," 

 or something analogous to it has been noticed in a large number of rodents.' The well- 



' See especially Nature, vol. xv, Popular Science Monthly, vol. i, and the American Naturalist. 



