NOT THE SOURCE OF ANIMAL HEAT. 29 



and of the par vagum. The respiratory motions con- 

 tinue for a time, but the oxygen does not meet with 

 those substances with which, in the normal state, it 

 would have combined ; because the paralyzed viscera 

 will no longer furnish them. The singular idea, that the 

 nerves produce animal heat, has obviously arisen from 

 the notion, that the inspired oxygen combines with car- 

 bon, in the blood itself ; in which case the temperature 

 of the body, in the above experiments, certainly, ought 

 not to have sunk. But, as we shall afterwards see, 

 there cannot be a more erroneous conception than this. 



As, by the division of the pneumogastric nerves, the 

 motion of the stomach and the secretion of the gastric 

 juice are arrested, and an immediate check is thus given 

 to the process of digestion, so the paralysis of the or- 

 gans of vital motion in the abdominal viscera affects the 

 process of respiration. These processes are most in- 

 timately connected ; and every disturbance of the ner- 

 vous system or of the nerves of digestion reacts visibly 

 on the process of respiration. 



The observation has been made, that heat is pro- 

 duced by the contraction of the muscles, just as in a 

 piece of caoutchouc, which, when rapidly drawn out, 

 forcibly contracts again, with disengagement of heat. 

 Some have gone so far as to ascribe a part of the 

 animal heat to the mechanical motions of the body, as 

 if these motions could exist without an expenditure of 

 force consumed in producing them ; how then, we may 

 ask, is this force produced ? 



By the combustion of carbon, by the solution of 

 3* 



