ause not derivable from
any other form.

Every species of animal has something about it that is unique and
individual and that no chemical or physiological analysis of it will
show--probably some mode of motion among its ultimate particles that is
peculiar to itself. This prevents cross-breeding among different species
and avoids a chaos of animal and vegetable forms. Living tissues and
living organs from one species cannot be grafted upon the individuals
of another species; the kidney of a cat, for instance, cannot be
substituted for that of a dog, although the functions and the anatomy of
the two are identical. It is suggested that an element of felineness and
an element of canineness adhere in the cells of each, and the two are
antagonistic. This specific quality, or selfness, of an animal pervades
every drop of its blood, so that the blood relationship of the different
forms may be thus tested, where chemistry is incompetent to show
agreement or antagonism. The reactions of life are surer and more subtle
than those of chemistry. Thus the blood relationship between birds and
reptiles is clearly shown, as is the relationship of man and the
chimpanzee and the orang-outang. The same general fact holds true in the
vegetable world. You cannot graft the apple upon the oak, or the plum
upon the elm. It seems as if there were the quality of oakness and the
quality of appleness, and they would not mix.

The same thing holds among different chemical compounds. Substances
which have precisely the same chemical formulae (called isomers) have
properties as widely apart as alcohol and ether.

If chemistry is powerless to trace the relationship between different
forms of life, is it not highly improbable that the secret of life
itself is in the keeping of chemistry?

Analytical science has reached the end of its tether when it has
resolved a body into its constituent elements. Why or how these elements
build up a man in the one case, and a monkey in another, is beyond its
province to say. It can deal with all the elements of the living body,
vegetable and animal; it can take them apart and isolate them in
different bottles; but it cannot put them together again as they were in
life. It knows that the human body is built up of a vast multitude of
minute cells, that these cells build tissues, that the tissues build
organs, that the organs build the body; but the secret of the man, or
the dog, or even the flea, is beyond its reach