THE METABOLISM OF THE BODY. 465 
is generally increased ; and this accounts for an additional in- 
crement of loss; while the lungs do extra work and exhale an 
increased quantity of aqueous vapor, so that in these various 
ways the body is cooled. Manifestly there is some sort of co- 
ordination between the processes of heat production and heat 
expenditure. The vaso-motor, secretory, and respiratory func- 
tions are modified. Even if an individual do no work at all, as 
when in a Turkish bath, it becomes evident, to one submitting 
to the experiment (for such it is or may become), that the 
pulse and respirations are quickened and that there is copious 
secretion of sweat following on reddening of the skin, owing 
to vascular dilatation. Exact quantitative estimation of the 
heat produced, as seen above, and of the oxygen used, the car- 
bonic anhydride and watery vapor exhaled, shows that the 
organs of which we are speaking are not only apparently but 
actually doing more work. It is usual to quote the case of 
Drs. Fordyce and Blagden, who learned to endure without 
injury a heat of 127° C. (260° F.), to illustrate the great adap-' 
tability of our own organism in this respect. We may suppose 
that the various co-ordinations effected, chiefly at all events 
through the central nervous system, and not by the direct ac- 
tion of the heat upon local nervous mechanisms, or the tissues 
themselves directly, are reflexes. 
The production of heat, however, seems to be Bute under 
the influence of the nervous system, though we know less about 
the details of the matter. 
A cold-blooded animal differs from a warm-blooded one in 
that its temperature varies with the surrounding medium more; 
hence the terms potkilothermer and homoiothermer for cold- 
blooded and warm-blooded, would be appropriate. 
Such an animal, as a frog or turtle, may have its chemical 
processes slowed or quickened, almost like those going on in a 
test-tube or crucible, by altering the temperature. Very different 
is it, as we have seen, in the normal state of the animal with 
any mammal. Hence hibernation or an allied state has become 
a necessary protection for poikilothermers, otherwise they 
would perish outright, and the groups become extinct in north- 
ern latitudes. Now, when a mammal is poisoned with curare, 
it becomes like a poikilothermer. Like the latter, under in- 
crease of temperature, it too uses more oxygen and produces 
more carbonic anhydride. When certain parts of the brain 
are divided or punctured, a fall, similar to that observable 
when curare is given, is observable. 
30 
