HUDSON 

 DISCUSSION 



VEGHTE: What is your definition of torpor; and is it reprodu- 

 cible? 



HUDSON: Do you mean is torpor reproducible in the particular 

 species'? Can I get an animal repeatedly in torpor? Yes, it is very 

 reproducible. We define torpor in two ways.Firstof all, the animal 

 has a body temperature which is within a degree or so of the envi- 

 ronmental temperature, and then secondly, he must be capable of 

 spontaneously arousing so that we could not include any application 

 of heat in order to get arousal for the animals. Incidentally this 

 spontaneous arousal is accompanied by shivering and other classical 

 manifestations of hibernation. 



HANNON: While you are defining things, would you define 

 "estivation"? Is there any difference between the two? 



HUDSON: Well, it looks like there is not, at this point. I 

 think a lot more work has to be done. I am not absolutely convinced 

 that there are not some subtle differences in the physiological 

 mechanisms of estivation and hibernation so that, as of now, esti- 

 vation is the hibernation response which occurs in the summer, 

 and, therefore, occurs at fairly high ambient temperatures. 



HANNON: I am asking about torpor versus estivation. Is it 

 the same or different? 



HUDSON: Well, it seems to me this kind of thing right now is 

 only a matter of opinion about usage of the word "torpor" rather 

 than being based on very much factual information. I am of the 

 opinion that estivation is a much more intermittent and brief kind 

 of a response than hibernation. Certainly both cases illustrate 

 torpor. 



WEST: I would like to comment on the difference between 

 results on heart rate responses of desert birds compared with 

 the sub-arctic birds that we have been working on. We find that 

 there is a continual linear relationship of heart rate to decreasing 



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