HIBERNATION AND ALLIED STATES IN ANIMALS 109 



in a tank in which the water is being continually 

 renewed by a slow stream. They are not fed. None 

 of the frogs seem to pass into a condition of true 

 hibernation, but they descend to the bottom of the 

 tank and remain quiet, as if asleep or partially torpid, 

 as, indeed, I know they often are for hours. In this 

 is an interesting modification of that most profound 

 torpor which they experience when buried in the mud 

 of ponds. 



Even in the winter life of a creature like the marmot 

 we may have all degrees of drowsiness or torpor, as I 

 have shown, and it is not to be forgotten that our 

 own daily sleep has its degrees, so that the night's 

 sleep may be represented by a curve with a sharp 

 rise and very gradual fall, which may, as we all know, 

 be greatly modified by circumstances. 



The same laws seem to apply to all the known cases 

 of human lethargy, hibernation, sleep, or whatever the 

 state may be called. In the case of the buried sheep 

 and hogs the protective value of the condition is 

 evident, as also in the case of the lethargic woman. 

 This individual, with so ill-balanced and unstaple a 

 constitution, would probably have been carried off by 

 some form of actual disease long before, had she 

 remained awake. She could exist as a mere vegeta- 

 tive organism, but not as a normal human being in the 

 ordinary struggle for existence. One thing which has 

 been much impressed upon me by my studies of this 

 whole subject, is the varying degrees of sensitiveness to 

 temperature and meteorological conditions in different 

 groups of animals and different individuals of the same 

 group. The bat as compared with the marmot, for 

 example, may be worked like a machine by varying the 

 temperature. On the contrary, the degree to which the 

 woodchuck is independent of temperature was a 

 surprise to me after my experience with the bat. But 



