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. The fluid containing carbonic acid, water,
and ammonia, which offers such a Barmecide feast 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 vigor, 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 plant
can raise the less complex substances--carbonic acid, water, and
ammonia--to the same stage of living protoplasm, if not to the same level.
But the plant also has its limitations. Some of the fungi, for example,
appear to need higher compounds to start with; and no known plant can live
upon the uncompounded elements of protoplasm. A plant supplied with pure
carbon, hydrogen, oxygen, and nitrogen, phosphorus, sulphur and the like,
would as infallibly die as the animal in his bath of smelling-salts,
though it would be surrounded by all the constituents of protoplasm. Nor,
indeed, need the process of simplification of vegetable food be carried so
far as this, in order to arrive at the limit of the plant's thaumaturgy.
Let water, carbonic acid, and all the other needful constituents be
supplied with ammonia, and an ordinary plant will still be unable to
manufacture protoplasm.

Thus the matter of life, so far as we know it (and we have no right to
speculate on any other), breaks up, in consequence of that continual death
which is the condition of its manifesting vitality, into carbonic acid,
water, and ammonia, which certainly possess no properties but those of
ordinary matter. And o