INTELLIGENCE, POWER, 



swamps, in the cool shade of forests, and on the high moun- 

 tain sides. Throughout all ages large animals have been 

 inhabitants of swamps or of the ocean. 



In the warm-blooded animals in the sea there was no 

 problem of heatstroke. Instead, the problem in the cold 

 polar seas was that of too much heat loss. Thus, in the 

 adaptation to the cold sea, nonconductors of heat, such as 

 oil, blubber, and fat, were evolved. The warm-blooded land 

 animals in the arctic evolved such devices for the prevention 

 of the loss of heat and death from freezing as fur, feathers, 

 wool, and fat, all of which are inert, insulating materials. 



In the tropics the temperature of the air may daily rise 

 higher than the temperature that causes disintegration of 

 protoplasm, or heatstroke. If the animals in the tropics 

 were ensheathed in a skin of copper or any heat conductor, 

 they would acquire an internal temperature that would 

 cause heatstroke. 



The greatest protector against the loss of heat is water. 

 The composition of animals is approximately three-fourths 

 water. Since water exhibits the highest known specific heat, 

 water gives the greatest protection against the adverse 

 effect of rapid changes in temperature. 



Protoplasm may be disintegrated as well as frozen. It is 

 a significant fact that the animals in the tropics are as 

 completely covered with hair for protection against too 

 much external heat as the animals in the north are covered 

 with fur for protection against too little external heat. A 

 Thermos bottle serves to keep its contents cold as well as 

 hot. 



The eland, the giraffe, the zebra, the kongoni, the wilde- 

 beest, the oryx, the impala, the Thomson's gazelle, the 

 dik-dik, the reedbuck, and the steinbok of the tropics are 

 all high-speed Herbivora. So also are the musk ox, the 

 caribou, the reindeer, the elk, and the moose of the north. 

 All are covered with hair, and when they run their internal 

 heat mounts so rapidly as to threaten heatstroke. 



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