VERTEBRATED ANIMALS. 77 



fishes, properly so called, partake the temperature of 

 the water in which they live, even to the point of free- 

 zing ; air breathing animals have the power of resisting 

 both heat and cold, and of preserving nearly the same 

 temperature, whatever that may be in which they are 

 placed. 



It is perhaps true, that to a certain degree, all animals, 

 and even trees, resist both heat and cold so long as the 

 vital principle remains active. But in the lower orders 

 of animals, this power is exceedingly feeble when com- 

 pared with that, which endows Quadrupeds and Man. 



Thus eels become as cold to the touch as the ice in 

 which they may be preserved, and yet the vital princi- 

 ple remains, since these creatures may be thus kept in 

 a torpid state, probably for any length of time, and then 

 again revived to life and activity. It is well known 

 also, that the gold fish may be frozen with the water in 

 its vase, and yet by a slow application of heat, become 

 as lively as ever, in the course of half an hour. In these 

 cases, and many others which will be mentioned hereaf- 

 ter, life is suspended, but its principle yet remains, and 

 although such animals do not preserve their temperature 

 like those of the higher orders, they are still endowed 

 with a much greater tenacity of life, for with a few 

 exceptions, when a warm blooded animal becomes 

 cold, the vital principle is not merely suspended, but is 

 extinct, and death ensues. 



The power of man, and also of quadrupeds and 

 birds, to resist changes of temperature, is indeed sur- 

 prising. With respect to the power of animals to 

 resist low degrees of temperature, every one who 

 resides in a cold climate has seen abundance of natural 

 examples. The turkey, for instance, will sleep comfort- 

 ably, perched on a high tree, entirely exposed to the 

 northern blast, when the thermometer is 30 degrees 

 below zero. Allowing the temperature of the bird to 

 be 100 degrees, which is not above the truth, then there 



What is said about the freezing of eels and fish 1 What animals have 

 the greatest tenacity of life, cold or warm blooded 1 What difference 

 sometimes exists between the temperature of the turkey and the air in 

 which he is? 



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