germs of marine and aquatic algæ may
be looked upon as young gentlemen with
flourishing prospects; who, under the
travelling title of Zoospore, make the grand
tour, before finally settling down to vegetate
in their country seats. Many are done for at
the outset of their rambles. Whence they
set forth, and what becomes of numbers of
them, nobody knows; they get strayed and
are caught up by brigands and sharpers;
while others, by pursuing a right and prudent
course, eventually make vigorous and
ornamental branches of the family tree.

Many of the protophytes, or primitive
plants—so called from their extreme
simplicity of structure, and not from any actual
proof of their preceding others in point of
time—appear to alternate between a motile
and a still condition. If we want an answer
to the question, "What are they—animals
or plants ?" the mode of nutrition amongst
these lowest organisms gives the most
probable answer. If they take organic
substances into their interior in short, if they
swallow and digest in any way—they must
be set down as animals: eating, the lowest
propensity of our nature, is the act which
first raises a creature above the rank of a
vegetable. If they absorb inorganic aliment
through their exterior, they may be safely
catalogued as vegetable in their constitution.
It has been suggested that, if animals, they
will absorb oxygen and give out carbonic-
acid gas; if vegetables the reverse—they will
have the power of liberating oxygen, through
the decomposition of carbonic acid, under the
influence of sunlight. The distinction is
acute, and very likely true; but, in the
crowded variety of microscopic creatures
which will be found mingled together pellmell
in the same drop of water, it is scarcely
possible to separate the sorts and test the
gases given out by each.

It seems a paradox that the organisation
of many creatures which are undoubtedly
animals, should be much less complex than
that of many which we must probably decide
to consider plants. The first forms of animal
life, called protozoa, or primitive animals,
and answering to the protophytes among
plants—such as the Amæba (formerly Proteus),
the Actinophrys, the Rhizopods in
general, and among them, to specify one
genus, the Arcellas—all appear to be
composed of a living, homogenous, contractile
jelly; to which that able microscopist,
Dujardin, gave the name of Sarcode. The quasi-
members which they put forth from, and
draw back into, their quasi-body at will, are
capable of uniting at their tips, or anywhere
else, as completely as one drop of water flows
into another. Yet, they eat, after their fashion.
Although destitute of a mouth, they ingulf,
and digest, other primitive animals and plants.
They extemporise an efficient stomach out of
the whole of their own proper person. They
envelop their prey in a fold more complete
than that which the fiercest boa can cast
around his victim. Thus, they are as truly
predacious as the lion, and as really herbivorous
as the cow and the antelope; they are
omnivorous, like man himself. Hence we see
that a positive and easily-defined distinction
between animals and plants consists,—first,
in the nature of their aliment; and, secondly,
in the method of its introduction. While
the protophyte obtains the materials of its
nutrition from the air and moisture that
surround it, the simplest protozoon is utterly
dependent for its support upon organic
substances previously elaborated by other
organisms. The protophyte imbibes and absorbs
liquid and gaseous molecules; the protozoon
ingests the solid particles that constitute its
food, and subjects them to a regular process
of digestion. If, therefore, structural
characters are insufficient to distinguish the
kingdom to which these simplest of created
beings belong, at least they seem to be
physiologically separable by the mode and materials
of their nutrition. Moreover, animalcules
that are green in colour and whose motions
are caused by cilia, or vibrating filaments,
may be looked upon as protophytes till there
is good proof to the contrary; while transparent
animalcules, whose movements do not
alone consist in the mere vibration of cilia,
(such as are performed by volvoxes and the
like), but are the changes taking place in a
contractile body, may be safely classed as
protozoa, since their actions bear a much
closer resemblance to those of the higher
animals.

Many of these fragments of animated
jelly even go so far as to secrete a shell
of considerable regularity and beauty. One
of the commonest Arcellas has a shell like
a broad-brimmed hat. Yet they have no
integument, or perceptible organs. The
naturalists who resolve every living organism
to a cell or an aggregate of cells, say
that these gelatinous animalcules represent
the contents of a cell without the cell-walls.
The cell is a purse intended to hold
something. Its only use is as a containing and
circumscribing wall. But in such specimens
as the Amæba and the Actinophrys, you have
the money without the purse.

Eating, then, even among the lowest
types, is the characteristic of animality. The
Oscillatorias, the Volvoxes, the Protococcuses,
and even the Euglenes, and the rest of the
individuals who are accused of being
locomotive plants, do not eat, and have no
means of eating, that we can discover.
They draw their nourishment, as far as we
can trace, entirely from water, carbonic-
acid, and ammonia, which they absorb through
their external surface only, and take in no
solid particles of any description.

At the first glance, indeed, motion, either
continuous or frequent, seems incompatible
with a vegetable nature; this is partly
caused by our not being familiar, on land,