IN THE ANIMAL ORGANISM. 241 



during their winter sleep, the capacity of increase in 

 mass (one of the chief manifestations of the vital 

 force), owing to the absence of food, is entirely sup- 

 pressed. In several, apparent death occurs in con- 

 sequence of the low temperature and of the diminu- 

 tion of vital energy thus produced ; in others, the 

 involuntary motions continue, and the animal pre- 

 serves a temperature independent of the surround- 

 ing temperature. The respirations go on ; oxygen, 

 the condition which determines the production of 

 heat and of force, is absorbed now as well as in the 

 former state of the animal ; and previous to the 

 winter sleep, we find all those parts of their body, 

 which in themselves are unable to furnish resistance 

 to the action of the oxygen, and which, like the 

 intestines and membranes, are not destined for the 

 change of matter, covered with fat ; that is, sur- 

 rounded by a substance which supplies the want of 

 resistance. 



If we now suppose, that the oxygen absorbed 

 during the winter sleep combines, not with the ele- 

 ments of living tissues, but with those of the fat, 

 then the living part, although a certain momentum 

 of motion be expended in keeping up the circula- 

 tion, will not be separated and expelled from the 

 body. 



With the return of the higher temperature, the 

 capacity of growth increases in the same ratio, and 

 the motion of the blood increases with the absorp- 

 tion of oxygen. Many of these animals become 



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