HEAT AND LIFE. 144 
of 45° to 50° (cent.). Larger ones endure heat better. 
Cold-blooded animals and the larve 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 
