EFFECTS OF HEAT ON ANIMALS. 147 



When Sir C. Blagden's first paper appeared, Mr. Chan- Changeux as- 



geux made some remarks on it.* He particularly endea- t0 evapoiation, 



voured to prove, that it was not by virtue of a particular 



property, that the human body resisted the effects of heat, 



but from causes purely physical. These causes, according partly toth* 



to him, were on the one hand the evaporation of the per- coo j in g °f the 



' r . * , air in its pas- 



spirable matter ; on the other the refrigeration of the air in- sage to the 



troduced into the lungs, the effects of its rapid passage Iun S s - 



through the trachea. He does not appear however, to have 



made any experiment on the subject. 



In 1779, Dr. Crawford, in the first edition of his worker Crawford, 



on animal heat, promulgated the opinion, that the faculty p ora r ^on°solpl" 



possessed by animals of producing cold depended solely on from the skin 



the evaporation of the perspirable matter pulmonary and ° ' 



cutaneous. Subsequently, in a paper in the Philosophical afterward in 



Transactions, and in the second edition of his work, he f™n ^mz zb- 



advanced a contrary opinion, founded on some experiments sorbed from the 



of which I shall give an account in another place. 



Having observed, that animals exposed to heat vitiated 

 the air less by respiration than such as were exposed to cold, 

 bethought he could explain by this fact the faculty of pro- 

 ducing cold which they possess. I shall not attempt here 

 to give an account of the theory he invented on this point, 

 a theory which I confess I do not very well understand. 



Such'afe the principal researches and observations, that, 

 to the best of my knowledge, have been published respect- 

 ing the influence of heat on animals. The subject how- 

 ever was far from exhausted, as several questions remained 

 undecided, and others even wholly neglected. A few in- 

 quiries, however incomplete, that I have made myself re- 

 specting it, will form the conclusion of this essay. They \ 

 are far from filling up the chasms that Avere left; but I shall 

 deem myself happy, if they throw some light on a few 

 points, and meet the indulgence of the enlightened judges, 

 to whom I submit them. 



It is incumbent on me to add, that the experiments, which 

 constitute the base of these researches, are not exclusively 

 my own; they were made in concert with my friend, Dr. 



* Journal de Physique, t. VII. p. 57. 

 ... Bcrger, 



