e fact. We shall revert to it hereafter.

Can it be believed, then, that protoplasm, as the origin of life, is
self-caused, and self-developed? And this is not all. I must briefly
remind my readers that the way in which animal protoplasm deals with the
elements of nutrition is quite opposite to that which plant protoplasm
follows. I might, indeed, have mentioned this at an earlier stage, when
I mentioned Professor Huxley's comparison of the chemical action in the
formation of water with what he assumed to be the case in the formation
of protoplasm. When water is formed, the two gases disappear, and an
_exactly equal weight_ of water appears in their place; but if living
protoplasm is enabled to imbibe liquid or other nutriment containing
ammonia, water, and carbonic acid, there is no disappearance of the
three elements and an equivalent weight of living protoplasm appearing
in its place. Protoplasm consumes the oxygen and sets free the carbonic
acid. Both kinds of protoplasm do this, until exposed to the light; and
then a difference is observed; for under the influence of light, animal
protoplasm alone continues to act in this way, and vegetable protoplasm
begins at once to develop little green bodies or corpuscles in its
cells, and afterwards acts in a totally opposite way, taking the carbon
into its substance and giving off the oxygen.[1]

[Footnote 1: Certain _fungi_ seem to afford an exception to this. The
above is, I believe, true as a theoretical action of plants and animals
in protoplasmic form. But practically, in all higher developments of
either kind, other distinctions come into play; e.g., that plants can
make use of inorganic matter, gases, and water, and elaborate them into
organic matter. Animals cannot do this, they require more or less solid
food--always requiring "complex organic bodies which they ultimately
reduce to much simpler inorganic bodies. They are thus mediately or
immediately dependent on plants for their subsistence" (Nicholson,
"Zoology," 6th ed. p. 17). It is perhaps with reference to this that in
the Book of Genesis the Creator is represented as giving _plant_ life to
the service of man and animals--while nothing is said of the preying of
_Carnivora_ and _Insectivora_ on animal life.]

Not only then has each kind of protoplasm its own mysterious character
impressed on it, and is compelled to act in a certain way; but still
further, each particle of animal and vegetable protoplasm, whe