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DR. CARPENTER ON THE MUTUAL RELATIONS OF 
was found that they died in from 12 to 32 minutes, when its temperature was 90° ; in 
from 35 to 90 minutes, when its temperature was 72° ; in from 350 to 375 minutes, 
when its temperature was 50°; and from 367 to 498 minutes, when it was cooled 
down to the freezing--point. The prolongation of life at the lower temperatures was 
not due to torpidity, for the animals performed the functions of voluntary motion 
and enjoyed the use of their senses ; but it was occasioned by the diminished activity 
of all their functions, and their consequent less demand for air. On the other hand, 
the elevation of temperature increases the demand for air, and occasions speedier 
death when it is withheld, chiefly by producing a vast acceleration in the rate at 
which all the operations, both of animal and organic life, take place. 
6. Although the warm-blooded animals are in great degree removed, by the inde- 
pendent calorifying power which they possess, from the influence of external tempe- 
rature, yet it is very easily shown that their vital activity is no less under the direct 
and immediate influence of heat, than is that of cold-blooded animals. In fact, it 
would seem to be for the sake of keeping up their vital energy to a certain high and 
uniform rate, that they are endowed with the heat-generating power ; and if this 
power be not exercised, and the body be cooled down, its vital activity is reduced, 
and at last extinguished. From the experiments of Chossat* it appears that Birds 
and Mammals cannot (except in the case of the hybernating species) be cooled down 
more than 30° below their natural standard, without the entire suspension of their 
animal and organic functions. This depression of temperature consequent upon pro- 
longed starvation, was found to take place as soon as all the fat and other disposable 
materials in the body had been burned off. But so soon as animals thus reduced to 
a moribund condition were subjected to external heat, which artificially raised the 
temperature of their bodies, their sensibility and muscular power were renewed ; 
they flew about the room, and took food when it was presented to them ; and their 
secretions were restored. If this artificial assistance was prolonged, until the digested 
aliment was prepared in sufficient amount to maintain the combustive process, they 
recovered ; but if it was withdrawn too soon, they died. — The hybernating species of 
Mammalia differ from the rest essentially in this, that the lowering of the tempera- 
ture of their bodies does not destroy their vitality, but merely suspends their activity, 
so that they are reduced for a time to a condition in all respects comparable to that 
of cold-blooded animals but little removed above absolute torpidity; and in this 
condition, all that has been said respecting the influence of external temperature upon 
the rate of life of cold-blooded animals, applies to them also. 
The vast mass of facts, of which the foregoing are examples, appears to the author 
to justify the conclusion, that Heat is something more than a stimulus capable of 
arousing a dormant vital force ; but, on the other hand, they by no means justify the 
assumption that heat and the “ vital principle ” are identical. That Heat, acting upon 
or through an Organized structure, then manifests itself as Vital force, — or that heat 
* Experiences sur ITnanition. 
