brisk, cold wind is blowing upon us.

570. As the primary object of the different processes of nutrition is
to supply animal heat, so the action of the different nutritive organs
is modified by the demands of the system for heat. When heat is
rapidly removed from the body, the functional activity of the organs
of nutrition is increased. When the system is warmed by foreign
influence, the activity of the nutritive organs is diminished. This
leads to the natural, and, we may add, instinctive change in the
quality and quantity of food at different seasons of the year.

-=-=-=-=-=-=-=-=-=-=-=-=

569. When is heat radiated from the body? When is it greatest? 570.
What is the primary object of the different processes of nutrition?
When is the activity of the nutritive organs increased? When
diminished? To what does this lead?

-=-=-=-=-=-=-=-=-=-=-=-=

CHAPTER XXVIII.

HYGIENE OF ANIMAL HEAT.

571. The amount of heat generated in man and inferior animals depends
upon the quantity and quality of the food, age, exercise, the amount
and character of the respired air, condition of the brain, skin, and
general system.

572. _Animal heat is modified by the proportion of digestible carbon
which the food contains, and by the quantity consumed._ As the kind of
fuel that contains the greatest amount of combustible material evolves
the most caloric when burned, so those articles of food that contain
the greatest quantity of carbon produce the most heat when converted
into blood. The inhabitants of the frigid zones, and individuals in
temperate climates during the cold season, consume with impunity
stimulating animal food, that contains a large proportion of carbon,
while the inhabitants of the tropical regions, and persons in
temperate climates during the warm season, are more healthy with a
less stimulating or vegetable diet.

_Observation._ When we ride or labor in cold weather, an adequate
amount of nutritious food will sustain the warmth of the system better
than intoxicating drinks.

573. _Age is another influence that modifies the generation of animal
heat._ The vital forces of the child being feeble, less heat is
generated in its system than in that of an adult. The experiments
of Dr. Milne Edwards show that the power of producing heat in
warm-blooded animals, is at its minimum at birth, and increases
successively to adult age; and that young children part with their
heat more readily than adults, and,