mals in the earliest periods of life; for this
food also contains substances, which are not necessary for their
support in the adult state. The nutrition of the young of carnivora
is obviously accomplished by means similar to those by which the
graminivora are nourished; their development is dependent on the
supply of a fluid, which the body of the mother secretes in the
shape of milk.

Milk contains only one nitrogenised constituent, known under the
name of caseine; besides this, its chief ingredients are butter
(fat), and sugar of milk. The blood of the young animal, its
muscular fibre, cellular tissue, nervous matter, and bones, must
have derived their origin from the nitrogenised constituent of
milk--the caseine; for butter and sugar of milk contain no nitrogen.

Now, the analysis of caseine has led to the result, which, after the
details I have given, can hardly excite your surprise, that this
substance also is identical in composition with the chief
constituents of blood, fibrine and albumen. Nay more--a comparison
of its properties with those of vegetable caseine has shown--that
these two substances are identical in all their properties;
insomuch, that certain plants, such as peas, beans, and lentils, are
capable of producing the same substance which is formed from the
blood of the mother, and employed in yielding the blood of the young
animal.

The young animal, therefore, receives in the form of caseine,--which
is distinguished from fibrine and albumen by its great solubility,
and by not coagulating when heated,--the chief constituent of the
mother's blood. To convert caseine into blood no foreign substance
is required, and in the conversion of the mother's blood into
caseine, no elements of the constituents of the blood have been
separated. When chemically examined, caseine is found to contain a
much larger proportion of the earth of bones than blood does, and
that in a very soluble form, capable of reaching every part of the
body. Thus, even in the earliest period of its life, the development
of the organs, in which vitality resides, is, in the carnivorous
animal, dependent on the supply of a substance, identical in organic
composition with the chief constituents of its blood.

What, then, is the use of the butter and the sugar of milk? How does
it happen that these substances are indispensable to life?

Butter and sugar of milk contain no fixed bases, no soda nor potash.
Sugar of milk has a compositio