AND ANIMAL LIFE. 187 



perspiration had protected the system from the 

 further production of heat : we might with truth 

 assert, that it had preserved it from its injurious 

 effects. If an individual be confined in a warm 

 moist atmosphere, or in heated water, he is very 

 soon oppressed, because perspiration is retarded 

 in the one case and prevented in the other, and 

 consequently the heat accumulates. 



CCIX. There is a great difference between 

 the powers that relieve the system from the 

 effects of heat and those that circumscribe its 

 evolution. The former are simply the exten- 

 sion of the ordinary and obvious laws of the ani- 

 mal economy ; the latter are the result of a prin- 

 ciple less evident, and exercised only on extra- 

 ordinary occasions. The excessive heat of 240 

 or 260 would destroy the body, if the 260 in- 

 creased the generation of heat in the ratio of its 

 numerical progression ; but every degree, from 

 the temperature of the body to 260, modifies the 

 production of heat by augmenting the rarefaction 

 of the air within the chest, thus successively dimi- 

 nishing the quantity of oxygen submitted to the in- 

 fluence of the blood. 



When an individual has been exposed to great 

 heat for some time, as in an oven for example, we 

 observe, that, on quitting this, his breathing is quick 

 and short, presenting symptoms somewhat simi- 

 lar to those occasioned by running, or excessive 

 exercise. When such arise from the latter causes, 



