MAMMALIAN COLD ACCLIMATION 



function of the surface or is related to surface area rather than 

 to metabolic size. 



HART: It might not make too much difference because they 

 are rather close anyway. 



KLEIBER; That is right, except when you go from one kilo- 

 gram to a thousand kilograms. 



MORRISON: They are close, but there is a difference between 

 the two functions. In our measurements, taking the thermal con- 

 ductance from the slopes of the metabolism- ambient temperature 

 curves, a rather elegant relation describes some of the smaller 

 mammals (<500 g). Thus, conductance is equal to the square root 

 of the body weight if the weight is expressed in grams and the con- 

 ductance in ccO (gms x hr x G) 

 2 



HART: If you express metabolism as a square root function 

 of body weight, it should then be independent of weight differences. 



MORRISON: The exponent will change depending on whether 

 the expression is per gram or per animal. That would change the 

 exponent. 



VIEREGK: In your figure comparing skin temperatures of 

 different species at different environmental temperatures, where 

 on the animal's body do you take the skin temperature? Do you have 

 any idea of how to get an average skin temperature for the surface? 



HART: It was not an average at all. They were simply repre- 

 sentative temperatures taken over the trunk of the body. 



VIERECK: But the fur is very thick in the back and thin in the 

 front. Where do you take the temperature? 



HART: This is underneath the fur, and in the caribou they 

 were averages of several measurements taken on one side of the 

 fur. In the rat measurements were approximately at the same place. 



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