GLEANINGS 
IN 
SCIENCE. 
JYo. 17. — JWay, 1830. 
I . — On Sensible Temperature. 
One Of the earliest and most remarkable applications of the doctrine of latent 
beat, was to explain the phenomenon of animal temperature. The caloric necessa- 
ry to the gaseous existence of the air we inspire, was supposed to be set free at the 
same time that the base of the gas was fixed in the blood ; and thence was 
inferred the constant production of heat, forming so peculiar a character of ani- 
mal existence. To this, however, it was plausibly objected, that were this the 
true explanation, the heat should be greater in the lungs and less at the 
extremities — a conclusion not agreeable to fact. Crawfurd endeavoured to 
mend the explanation, by determining, as he thought he did, that the capacity 
for caloric of the arterial blood is greater than that of the venous blood ; and 
that the caloric set free by the fixing of the respirable gases, was absorbed by the 
arterial blood, and again given out in its passage through the body, and gradual con- 
version into venous blood. To this was objected tbe inaccuracy of bis determi- 
nations, the capacities being, as nearly as possible, equal ; and latterly still more de- 
cisively Mr. Brodie’s experiment, in which artificial respiration being kept up after 
death, the body cooled more rapidly than when, as in ordinary cases, the lungs 
were allowed to collapse. Mr, Brodie advocated the opinion, that the brain and 
spinal marrow are the source of animal heat, but failed to show in what manner, 
or by what means the) 7 performed this function. There are many facts that render 
his opinion probable— such as the coldness of a paralytic limit, the heat diffused 
by receiving food or stimulating liquors, or even cold water into the stomach. 
Perhaps the heat evolved in topical inflammation may be considered less connect- 
ed with this source. Dr. Thompson thinks too, that we must admit some con- 
nection between the heat developed in the body and the function of respiration ; 
because, as he says, those animals, whose respiratory organs are most perfect, and 
who respire the greatest quantity of air, have a warmer blood, and vice versa. But 
this argument is not conclusive ; for vve know that the perfection ot the several 
functions of the body keep pace with the developement of the nervous system. 
Thus the warm-blooded animals, which breathe by lungs instead of gills, have also 
a more fully developed nervous system- As the three tacts are co-existent, it is 
not easy to say, a priori , which two should stand in the relation of effects. 
Mr. Brodie’s opinion has been again recently controverted by Dr. Edwards, who 
returns to that of Crawfurd. To the usual arguments, he adds the important fact, 
that Dr. W. Philip and Dr. Le Gallois, in repeating Mr. Brodie’s experiment, obtain- 
ed different results — that is, by keeping up artificial respiration after decapitation 
they found the temperature decrease less rapidly than if no such operation was per- 
formed. Dr. Philip accounts for Mr. Brodie’s result in this way. In ordinary cir- 
cumstances the function of respiration is performed in a very gentle manner. If 
too much air be forced into the lungs, it lias been proved that an animal, in a state 
of suspended animation, will be irrecoverably killed. But by introducing more air 
into the lungs of the decapitated animal than was required, aud more rapidly not 
only was the heat extricated by respiration carried off, but even the cooling process 
accelerated. By pursuing the opposite course, Dr. Philip found the temperature of 
a rabbit 100° at the end of an hour ; while the animal, treated in Mr. Brodie s way, 
was only 98°. 
The results in Dr- Philip’s experiments do not seem either conclusive or satisfac- 
tory. In particuiur the effect seems always too small, and such as might be ac- 
