a, would not
outweigh that of all the higher living beings which inhabit the land put
together. And in ancient times, no less than at the present day, such
living beings as these have been the greatest of rock builders.

What has been said of the animal world is no less true of plants.
Imbedded in the protoplasm at the broad, or attached, end of the nettle
hair, there lies a spheroidal nucleus. Careful examination further
proves that the whole substance of the nettle is made up of a repetition
of such masses of nucleated protoplasm, each contained in a wooden case,
which is modified in form, sometimes into a woody fibre, sometimes into
a duct or spiral vessel, sometimes into a pollen grain, or an ovule.
Traced back to its earliest state, the nettle arises as the man does, in
a particle of nucleated protoplasm. And in the lowest plants, as in the
lowest animals, a single mass of such protoplasm may constitute the
whole plant, or the protoplasm may exist without a nucleus.

Under these circumstances it may well be asked, how is one mass 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 favour 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, or 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
th