xion between the two great kingdoms of living things is so
complete that separation is now regarded as impossible. For a long time
naturalists endeavored to frame definitions such as would, the one
include all plants and exclude all animals, and the other include all
animals and exclude all plants. But they have been so repeatedly foiled
in the attempt that they have given it up. There is no chemical
distinction which holds; there is no structural distinction which
holds; there is no functional distinction which holds; there is no
distinction as to mode of existence which holds. Large groups of the
simpler animals contain chlorophyll, and decompose carbonic acid under
the influence of light, as plants do. Large groups of the simpler
plants, as you may observe in the diatoms from any stagnant pool, are no
less actively locomotive than the minute creatures classed as animals
seen along with them. Nay, among these lowest types of living things, it
is common for the life to be now predominantly animal and presently to
become predominantly vegetal. The very name _zoospores_, given to germs
of _algae_, which for a while swim about actively by means of cilia, and
presently settling down grow into plant-forms, is given because of this
conspicuous community of nature. So complete is this community of nature
that for some time past many naturalists have wished to establish for
these lowest types a sub-kingdom, intermediate between the animal and
the vegetal: the reason against this course being, however, that the
difficulty crops up afresh at any assumed places where this intermediate
sub-kingdom may be supposed to join the other two.

Thus the assumption on which Mr. Martineau proceeds is diametrically
opposed to the conviction of naturalists in general.

* * * * *

Though I do not perceive that it is specifically stated, there appears
to be tacitly implied a fourth difficulty of allied kind--the difficulty
that there is no possibility of transition from life of the simplest
kind to mind. Mr. Martineau says, indeed, that there can be "with only
vital resources, as in the vegetable world, no beginning of mind:"
apparently leaving it to be inferred that in the animal world the
resources are such as to make the "beginning of mind" comprehensible.
If, however, instead of leaving it a latent inference, he had
distinctly asserted a chasm between mind and bodily life, for which
there is certainly quite