Here - The Alfred Russel Wallace Website

CHAP.
land-shells and sea-shells, and ultimately to everything which
by moving and feeding, by growing and dying, showed that
it was, like himself, alive. Here, probably, he would rest for
awhile, and it might require several generations of incipient
philosophers to extend the great generalisation of " life " to
that omnipresent clothing of the earth's surface produced by
the infinitely varied forms of vegetation.
The more familiar
any phenomenon is the more it is absolutely essential to
our life and well-being the less attention we pay to it and
the less it seems to need any special explanation. Trees,
shrubs, and herbs, being outgrowths from the soil, being
incapable of any bodily motion and usually exhibiting no
indications of sensation, might well have been looked upon
as a necessary appendage of the earth, analogous to the hair
of mammals or the feathers of birds. It was probably long
before their endless diversity attracted much notice, except
in so far as the fruits or the roots were eatable, or the stems
while the idea
or foliage or bark useful for huts or clothing ;
that there is in them any essential feature connecting them
with animals and entitling them to be classed all together
as members of the great world of life would only arise at a
considerably later stage of development.
It is, in fact, only in recent times that the very close
resemblance of plants and animals has been generally
recognised. The basis of the structure of both is the almost
indistinguishable cell ; both grow from germs ; both have a
varied life-period from a few months to a maximum of a
few hundreds of years ; both in all their more highly organised
forms, and in many of their lower types also, are bisexual ;
both consist of an immense variety of distinct species, which
can be classified in the same way into higher and higher
groups ; the laws of variation, heredity, and the struggle for
existence apply equally to both, and their evolution under
these laws has gone on in a parallel course from the earliest
periods of the geological record.
The differences between plants and animals are, however,
equally prominent and fundamental. The former are, with
few exceptions, permanently attached to the soil ; they
absorb nourishment in the liquid or gaseous state only, and
their tissues are almost wholly built up from inorganic