n closely allied to that of the other
kinds of sugar, of starch, and of gum; all of them contain carbon
and the elements of water, the latter precisely in the proportion to
form water.

There is added, therefore, by means of these compounds, to the
nitrogenised constituents of food, a certain amount of carbon; or,
as in the case of butter, of carbon and hydrogen; that is, an excess
of elements, which cannot possibly be employed in the production of
blood, because the nitrogenised substances contained in the food
already contain exactly the amount of carbon which is required for
the production of fibrine and albumen.

In an adult carnivorous animal, which neither gains nor loses
weight, perceptibly, from day to day, its nourishment, the waste of
organised tissue, and its consumption of oxygen, stand to each other
in a well-defined and fixed relation.

The carbon of the carbonic acid given off, with that of the urine;
the nitrogen of the urine, and the hydrogen given off as ammonia and
water; these elements, taken together, must be exactly equal in
weight to the carbon, nitrogen, and hydrogen of the metamorphosed
tissues, and since these last are exactly replaced by the food, to
the carbon, nitrogen, and hydrogen of the food. Were this not the
case, the weight of the animal could not possibly remain unchanged.

But, in the young of the carnivora, the weight does not remain
unchanged; on the contrary, it increases from day to day by an
appreciable quantity.

This fact presupposes, that the assimilative process in the young
animal is more energetic, more intense, than the process of
transformation in the existing tissues. If both processes were
equally active, the weight of the body could not increase; and were
the waste by transformation greater, the weight of the body would
decrease.

Now, the circulation in the young animal is not weaker, but, on the
contrary, more rapid; the respirations are more frequent; and, for
equal bulks, the consumption of oxygen must be greater rather than
smaller in the young than in the adult animal. But, since the
metamorphosis of organised parts goes on more slowly, there would
ensue a deficiency of those substances, the carbon and hydrogen of
which are adapted for combination with oxygen; because, in the
carnivora, nature has destined the new compounds, produced by the
metamorphosis of organised parts, to furnish the necessary
resistance to the action of the oxygen, and to produce