another be substituted in its place? If not, can
anything that is positive, and if anything, what, be said as to the
question of specific origination?

Now, in the first place, it is of course axiomatic that the laws which
conditioned the evolution of extinct and of existing species are of as much
efficacy at this moment as at any preceding period, that they _tend_ to the
manifestation of new forms as much now as ever before. It by no means
necessarily follows, however, that this tendency is actually being carried
into effect, and that new species of the higher animals and plants are
actually now produced. They may be so or they may not, according as
existing circumstances favour, or conflict with, the action of those laws.
It is possible that lowly organized creatures may be continually evolved at
the present day, the requisite conditions being more or less easily
supplied. There is, however, no similar evidence at present as to higher
forms; while, as we have seen in Chapter VII., there are _a priori_
considerations which militate against their being similarly evolved. {226}

The presence of wild varieties and the difficulty which often exists in the
determination of species are sometimes adduced as arguments that high forms
are now in process of evolution. These facts, however, do not necessarily
prove more than that some species possess a greater variability than
others, and (what is indeed unquestionable) that species have often been
unduly multiplied by geologists and botanists. It may be, for example, that
Wagner was right, and that all the American monkeys of the genus cebus may
be reduced to a single species or to two.

With regard to the lower organisms, and supposing views recently advanced
to become fully established, there is no reason to think that the forms
said to be evolved were new species, but rather reappearances of definite
kinds which had appeared before and will appear again under the same
conditions. In the same way, with higher forms similar conditions must
educe similar results, but here practically similar conditions can rarely
obtain because of the large part which "descent" and "inheritance" always
play in such highly organized forms.

Still it is conceivable that different combinations at different times may
have occasionally the same outcome just as the multiplications of different
numbers may have severally the same result.

There are reasons, however, for thinking it possible that th