ADAPTATIONS TO DESEFTS 



WEST : I think that with the technique I mentioned yesterday, 

 the power frequency distribution, we can single out the heart 

 rate. It is so constant. It comes out as a peak in the power spec- 

 trum, no matter how much shivering is masking it on the oscillo- 

 graph record. 



IRVING: Do you give a Poor- will any test to find what its 

 mental state is in a thermo-neutral zone? Is it entirely alert? 

 Can it still do multiplication? 



HUDSON: Well, he recognizes me in the thermo-neutral zone. 

 I do not know whether that is a very good test or not. 



IRVING: You do not see any noticeable signs of a mental state 

 characterizing torpidity? That would be my main question; is 

 that a normal resting basal rate? 



HANNON: I noticed in your oxygen consumption of the Mohave 

 ground squirrel, going in and out of torpor, that he lowered his 

 oxygen consumption as he went into torpor. It looked like he may 

 have lowered it more than he should. When he came out it appeared 

 that there was an oxygen deficit. The oxygen consumption went way 

 up. 



HUDSON: This is overshoot. Yes, this is characteristic in 

 arousing from hibernation, and I am not entirely clear on what 

 this may all mean in terms of the internal physiology of the animal, 

 at that time, whether there is some sort of a heat storing going 

 on, assuming that the overshoot does not coincide with attainment 

 of a normal body temperature. It is easier to explain in animals 

 that restrict the development of body temperature to the fore 

 quarters which is different from our desert ground squirrels. That 

 is, for instance, the 13 lined ground squirrel on arousing from 

 hibernation, typically has the anterior end of the animal develop- 

 ing normal body temperature first before the posterior end does, 

 and we get no such responses. That is, we have never observed 

 anything like this and we assume that it is related to the fact that 

 these animals have rather high body temperatures to begin with. 



451 



