BRODIE, PHILIP, AND TIEDMANN. 559 



chemist is always more or less imperfect, and 

 attended with loss from radiation, not to mention 

 other sources of error. 



My own opinion is, that instead of invalidating 

 the experiments of Dulong and Despretz are 

 strongly in favour of the chemical theory pro- 

 posed by Black, and supported by the most dis- 

 tinguished physiologists of modern times. In 

 regard to the hypothesis of M. Despretz, that 

 " the small remaining portion" of caloric not ac- 

 counted for by respiration, is generated by mo- 

 tion of the blood, friction, assimilation, &c. I 

 answer, that whenever the process of respiration 

 is arrested, the motion of the blood, friction, 

 assimilation, &c. are no longer carried on, and 

 that the temperature of the whole system falls 

 rapidly to that of the surrounding medium. 



In reply to the arguments of Brodie, Philip, 

 Tiedmann, Edwards, and others, who contend 

 that animal heat is generated by nervous in- 

 fluence, secretion, nutrition, the condition of the 

 blood, and muscular contraction, I shall proceed 

 to prove that the mean healthy temperature of all 

 animals is directly in proportion to the amount 

 of their respiration ; without which there could 

 be no sanguification, secretion, nutrition, nervous 

 influence, nor muscular contraction, and that 

 they have mistaken effects for the cause of animal 

 heat. 



