ra, whose food contains
relatively so small a proportion of the constituents of blood, the
process of metamorphosis in existing tissues, and consequently their
restoration or reproduction, must go on far less rapidly than in the
carnivora. Otherwise, a vegetation a thousand times as luxuriant would
not suffice for their sustenance. Sugar, gum, and starch, which form so
large a proportion of their food, would then be no longer necessary to
support life in these animals, because in that case the products of
waste, or metamorphosis of organised tissues, would contain enough
carbon to support the respiratory process.

When exercise is denied to graminivorous and omnivorous animals this is
tantamount to a deficient supply of oxygen. The carbon of the food, not
meeting with a sufficient supply of oxygen to consume it, passes into
other compounds containing a large excess of carbon--or, in other words,
fat is produced. Fat is thus an abnormal production, resulting from a
disproportion of carbon in the food to that of the oxygen respired by
the lungs or absorbed by the skin. Wild animals in a state of nature do
not contain fat. The production of fat is always a consequence of a
deficient supply of oxygen, for oxygen is absolutely indispensable for
the dissipation of excess of carbon in the food.

_V.--Animal Life-Chemistry_

The substances of which the food of man is composed may be divided into
two classes--into nitrogenised and non-nitrogenised. The former are
capable of conversion into blood, the latter incapable of this
transformation. Out of those substances which are adapted to the
formation of blood are formed all the organised tissues. The other class
of substances in the normal state of health serve to support the process
of respiration. The former may be called the plastic elements of
nutrition; the latter, elements of respiration.

Among the former we may reckon--vegetable fibrine, vegetable albumen,
vegetable casein, animal flesh, animal blood.

Among the elements of respiration in our food are--fat, starch, gum,
cane sugar, grape-sugar, sugar of milk, pectine, bassorine, wine, beer,
spirits.

The nitrogenised constituents of vegetable food have a composition
identical with that of the constituents of the blood.

No nitrogenised compound the composition of which differs from that of
fibrine, albumen, and casein, is capable of supporting the vital process
in animals.

The animal organism undoubtedly posse