HETEBOTHEBMY IN HOMEOTHEBMS 



JOHANSEN: No. 



IRVING: I think this would be a very valuable thing to deter- 

 mine, especially when sled-dog running is so well cultivated here; 

 you might even use such information to get good teams of dogs. 



JOHANSEN: Of course I would like to measure running caribou 

 and, when I get back to Norway, the reindeer, which is domesticated 

 and used for transportation. 



HART : I would like to mention this in connection that even in 

 the small mammals such as mice and rats body temperatures up 

 to 40° G or 41° G may be obtained during exercise of 20 or 30 

 minutes duration. It is commonly possible to do this in a rela- 

 tively warm environmentaltemperature. However, in a cool environ- 

 ment, the body temperature may not rise at all. 



JOHANSEN: Their insulation of course is poor. 



HART: The insulation is markedly inferior. With the husky 

 dog, you apparently never reach the condition where the tempera- 

 ture is low enough to cause this effect. 



HANNON; Along similar lines it mightbe worth mentioning that 

 the rectal temperatures of cold acclimatized rats are quite readily 

 elevated to very high levels when they are injected or infused intra- 

 venously with norepinephrine. A number of times, for example, we 

 have observed body tem.peratures as high as 43 C or 44 G in 

 experiments with this hormone. 



JOHANSEN: Of course this concept of heterothermy and the 

 potential of insulation somewhat invalidates the things we have 

 been taught in school about the climatic rules. I was wondering 

 whether Dr. Irving would care to comment about how this might 

 invalidate Allen's Rule about the length of extremities. 



IRVING: I think those rules are useless. 



PROSSER: There is still a correlation, just the same. 



171 



