is all. If digestion were a thing to be trifled with, I might
sup upon lobster, and the matter of life of the crustacean would undergo
the same wonderful metamorphosis into humanity. And were I to return to
my own place by sea, and undergo shipwreck, the crustacean might, and
probably would, return the compliment, and demonstrate our common nature
by turning my protoplasm into living lobster. Or, if nothing better were
to be had, I might supply my wants with mere bread, and I should find
the protoplasm of the wheat-plant to be convertible into man with no
more trouble than that of the sheep, and with far less, I fancy, than
that of the lobster.

Hence it appears to be a matter of no great moment what animal, or what
plant, I lay under contribution for protoplasm, and the fact speaks
volumes for the general identity of that substance in all living beings.
I share this catholicity of assimilation with other animals, all of
which, so far as we know, could thrive equally well on the protoplasm of
any of their fellows, or of any plant; but here the assimilative powers
of the animal world cease. A solution of smelling-salts in water, with
an infinitesimal proportion of some other saline matters, contains all
the elementary bodies which enter into the composition of protoplasm;
but, as I need hardly say, a hogshead of that fluid would not keep a
hungry man from starving, nor would it save any animal whatever from a
like fate. An animal cannot make protoplasm, but must take it ready-made
from some other animal, or some plant--the animal's highest feat of
constructive chemistry being to convert dead protoplasm into that living
matter of life which is appropriate to itself.

Therefore, in seeking for the origin of protoplasm, we must eventually
turn to the vegetable world. A fluid containing carbonic acid, water,
and nitrogenous salts, which offers such a Barmecide feast[52] to the
animal, is a table richly spread to multitudes of plants; and, with a
due supply of only such materials, many a plant will not only maintain
itself in vigour, but grow and multiply until it has increased a
million-fold, or a million million-fold, the quantity of protoplasm
which it originally possessed; in this way building up the matter of
life, to an indefinite extent, from the common matter of the universe.

Thus, the animal can only raise the complex substance of dead protoplasm
to the higher power, as one may say, of living protoplasm; while the