HEAT AND LIFE. 147 



of 45 to 50 (cent.). Larger ones endure heat better. 

 Cold-blooded animals and the larvae of insects resist more 

 energetically than warm-blooded animals ; but the reverse 

 is the case with fully-developed insects. 



Delaroche and Berger studied the human subject, too, 

 from the same point of view, and ascertained that the effect 

 produced varies with individuals. Thus from 49 to 58 

 the stove grew insupportable to Delaroche himself, who be- 

 came ill from the experiment, while Berger was scarcely 

 fatigued by it. On the other hand, Berger could remain 

 only seven minutes in a medium heated to 87, while Blag- 

 den staid twelve minutes in it. In tropical countries the 

 heat often rises during the day above 40 without troubling 

 the natives. At the Cape of Good Hope the thermometer 

 marks 43. Yet sometimes such a heat is murderous. It 

 is related, among other cases, that in the month of June, 

 1738, in the streets of Charleston, several persons died un- 

 der the influence of 41. In Africa our soldiers are often 

 known to be attacked with madness and to die in making 

 a long march, under the rays of a burning sun, but here 

 the influence of light is combined with that of heat. Du- 

 hamel mentions the account of several servant-girls of a 

 baker, who could remain without any inconvenience at all 

 for nearly ten minutes in an oven heated to the necessary 

 degree for baking bread. The experiment has since been 

 repeated. There is nothing contradictory in these facts. 

 An animal can endure for some time a temperature much 

 higher than its own, because the very profuse transpiration 

 which occurs in such a case prevents the heating of the or- 

 gans ; yet, as we shall see, so soon as the internal heat 

 really rises a few degrees above the normal figure, life is no 

 longer possible. 



The study of these phenomena had scarcely been carried 

 further, when in 1842 Claude Bernard devoted to it certain 

 researches, which he resumed and finished last year, and of 



