st at other
varieties, which particular races of men exhibit, is an instinct which
they cannot avoid obeying. Instead of exciting our disgust, as it too
frequently does, it should exalt our admiration of the infinite wisdom
of the Creator, who by simply adapting man's desire for particular kinds
of food to the external conditions under which he is placed, enables him
to occupy and "subdue the earth" from the Equator to the Poles.

The food of human beings and of the lower animals who inhabit cold
countries is nearly exclusively composed of animal substances.
The flesh, fat, and oil of animals occupy less space than do the
corresponding elements of vegetables; consequently the nutriment they
afford is more concentrated, and a larger quantity can be stowed away
without inconvenience in the stomach. The heat-forming constituents of
these substances constitute not only the chief part of their bulk, but
they are also capable of evolving a greater amount of heat than any
other of the respiratory elements. One pound of dry fat will develop as
much heat as two and a half pounds of dry starch, and the fattest flesh
includes four times as much plastic materials as rice. The diet of
people all over the world, unless under circumstances which prevent the
gratification of the natural appetite, establishes the intimate relation
which subsists between cold and food. The appetite of man is at a
minimum at the Equator, and at a maximum within the Arctic circle. The
statements as to the voracity of Hottentots and Bosjesmans, recorded in
the narratives of travellers, do not in the slightest degree affect the
general rule that more is eaten in cold climates than in hot regions.
These are mere records of gluttony, and it would not be difficult to
find parallel cases in our own country. Gluttony is an abnormal
appetite, and the greater part of the food devoured under its unnatural,
and generally unhealthy stimulus is not applied to the wants of the body.

The bodies of animals are heated masses of matter, and are subject to
the ordinary laws of _radiation_. Every substance radiates its heat, and
receives in return a portion of that emitted from surrounding bodies. If
two bodies of unequal temperature be placed near each other, the warmer
of the two will radiate a portion of its heat to the colder, and will
receive some of the heat of the latter in return; but as the warmer body
will emit more heat than it will receive, the result will be, th