animal heat.
What is wanting for these purposes an Infinite Wisdom has supplied
to the young in its natural food.

The carbon and hydrogen of butter, and the carbon of the sugar of
milk, no part of either of which can yield blood, fibrine, or
albumen, are destined for the support of the respiratory process, at
an age when a greater resistance is opposed to the metamorphosis of
existing organisms; or, in other words, to the production of
compounds, which, in the adult state, are produced in quantity amply
sufficient for the purpose of respiration.

The young animal receives the constituents of its blood in the
caseine of the milk. A metamorphosis of existing organs goes on, for
bile and urine are secreted; the materials of the metamorphosed
parts are given off in the form of urine, of carbonic acid, and of
water; but the butter and sugar of milk also disappear; they cannot
be detected in the faeces.

The butter and sugar of milk are given out in the form of carbonic
acid and water, and their conversion into oxidised products
furnishes the clearest proof that far more oxygen is absorbed than
is required to convert the carbon and hydrogen of the metamorphosed
tissues into carbonic acid and water.

The change and metamorphosis of organised tissues going on in the
vital process in the young animal, consequently yield, in a given
time, much less carbon and hydrogen in the form adapted for the
respiratory process than correspond to the oxygen taken up in the
lungs. The substance of its organised parts would undergo a more
rapid consumption, and would necessarily yield to the action of the
oxygen, were not the deficiency of carbon and hydrogen supplied from
another source.

The continued increase of mass, or growth, and the free and
unimpeded development of the organs in the young animal, are
dependent on the presence of foreign substances, which, in the
nutritive process, have no other function than to protect the
newly-formed organs from the action of the oxygen. The elements of
these substances unite with the oxygen; the organs themselves could
not do so without being consumed; that is, growth, or increase of
mass in the body,--the consumption of oxygen remaining the
same,--would be utterly impossible.

The preceding considerations leave no doubt as to the purpose for
which Nature has added to the food of the young of carnivorous
mammalia substances devoid of nitrogen, which their organism cannot
employ for nutriti