242 ANIMAL HEAT. 



many months in atmospheres in which the same animals, 

 in their full activity would be speedily suffocated. During 

 the periods of complete torpor, their respiration almost 

 entirely ceases ; the heart acts very slowly and feebly ; the 

 processes of organic life are all but suspended, and the 

 animal may be with impunity completely deprived of 

 atmospheric air for a considerable period. Spallanzani 

 kept a marmot, in this torpid state, immersed for four 

 hours in carbonic acid gas, without its suffering any 

 apparent inconvenience. Dr. Marshall Hall kept a lethar- 

 gic bat under water for sixteen minutes, and a lethargic 

 hedgehog for 22 j minutes; and neither of the animals 

 appeared injured by the experiment. 



CHAPTEE YIII. 



ANIMAL HEAT. 



INTIMATELY associated with the process of respiration are 

 the production of animal heat and the maintenance of a 

 uniform temperature of the body ; conditions as essential 

 to the continuance of life in warm-blooded animals, as 

 the extrication of carbonic acid and the absorption of 

 oxygen are. 



The average temperature of the human body, in those in- 

 ternal parts which are most easily accessible, such as the 

 mouth and rectum, may be estimated at from 98 to 103 

 F. In children the temperature is commonly as high as 

 102 F. In old persons it is about the same as in adults. 

 Of the external parts of the body, the temperature becomes 

 lower the further they are removed from the centre of the 

 body; Jhus, in the human subject, a thermometer placed 



