of
non-nucleated protoplasm to be distinguished from another? Why call one
"plant" and the other "animal"?

The only reply is that, so far as form is concerned, plants and animals
are not separable, and that, in many cases, it is a mere matter of
convention whether we call a given organism an animal or a plant. There is
a living body called _Aethalium septicum_, which appears upon decaying
vegetable substances, and, in one of its forms, is common upon the
surfaces of tan-pits. In this condition it is, to all intents and
purposes, a fungus, and formerly was always regarded as such; but the
remarkable investigations of De Bary have shown that, in another
condition, the _Aethalium_ is an actively locomotive creature, and takes in
solid matters, upon which, apparently, it feeds, thus exhibiting the most
characteristic feature of animality. Is this a plant, or is it an animal?
Is it both, or is it neither? Some decide in favor of the last
supposition, and establish an intermediate kingdom, a sort of biological
"No Man's Land," for all these questionable forms. But, as it is
admittedly impossible to draw any distinct boundary line between this no
man's land and the vegetable world, on the one hand, and the animal, on
the other, it appears to me that this proceeding merely doubles the
difficulty which, before, was single.

Protoplasm, simple or nucleated, is the formal basis of all life. It is
the clay of the potter, which, bake it and paint it as he will, remains
clay, separated by artifice, and not by nature, from the commonest brick
or sun-dried clod.

Thus it becomes clear that all living powers are cognate, and that all
living forms are fundamentally of one character. The researches of the
chemist have revealed a no less striking uniformity of material
composition in living matter.

In perfect strictness, it is true that chemical investigation can tell us
little or nothing, directly, of the composition of living matter, inasmuch
as such matter must needs die in the act of analysis; and upon this very
obvious ground, objections, which I confess seem to me to be somewhat
frivolous, have been raised to the drawing of any conclusions whatever
respecting the composition of actually living matter, from that of the
dead matter of life, which alone is accessible to us. But objectors of
this class do not seem to reflect that it is also, in strictness, true
that we know nothing about the composition of any body whatever, as it