instead of being warmer, are
generally a degree or two colder. After adult age, as the vital powers
decline, the generation of heat is diminished, as the energies of
the system are lessened. Hence the young child, and the debilitated
aged person, need more clothing than the vigorous individual of
middle age.

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571-585. _Give the hygiene of animal heat._ 571. State some of the
influences that modify the generation of animal heat. 572. What
element of the food influences the generation of heat? When and
where can animal food be eaten with impunity? Give the practical
observation.

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574. _Exercise is an influence that modifies the generation of animal
heat._ As carbon and hydrogen enter into the composition of the organs
of the body, whatever increases the flow of blood in the system,
increases also the deposition of new material, and the removal of the
waste particles. This change among the particles of matter is attended
with an elevation of temperature, from the union of oxygen with the
carbon and hydrogen of the waste atoms. For this reason, a person in
action is warmer than in a quiescent state. Consequently, the amount
of clothing should be increased, when exercise or labor is diminished
or suspended.

575. On the other hand, whatever impedes the circulation and the
interchange of the atoms of matter, diminishes animal heat. Common
observation shows, that the extremities are not as warm when tight
gloves or boots are worn as when they are loose. One reason is, the
circulation of blood is impeded, which is attended with less frequent
change of the particles of matter.

576. _The quantity of air which is inhaled modifies the heat of the
system._ In the generation of heat in a stove, air, or oxygen, is as
essential as the wood or coal. It is equally so in the production of
animal heat. The oxygen of the inspired air should be in proportion to
the carbon and hydrogen to be consumed. This requires voluminous
lungs, together with free movements of the ribs and diaphragm. A
person whose chest is small, and whose apparel is worn tight over the
ribs, suffers more from the cold, and complains more frequently of
chilliness and cold extremities, than the broad-chested and loosely
dressed.

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What do the experiments of Dr. Milne Edwards show? 574. Why does
exercise influence animal heat? 575. What is the effect when the
circulation of blo