The Darwinian Hypothesis | Page 4

the heirs of Bacon
and the acquitters of Galileo. We must weigh this hypothesis strictly in
the controversy which is coming, by the only tests which are
appropriate, and by no others whatsoever.
The hypothesis to which we point, and of which the present work of Mr.

Darwin is but the preliminary outline, may be stated in his own
language as follows:--"Species originated by means of natural selection,
or through the preservation of the favoured races in the struggle for
life." To render this thesis intelligible, it is necessary to interpret its
terms. In the first place, what is a species? The question is a simple one,
but the right answer to it is hard to find, even if we appeal to those who
should know most about it. It is all those animals or plants which have
descended from a single pair of parents; it is the smallest distinctly
definable group of living organisms; it is an eternal and immutable
entity; it is a mere abstraction of the human intellect having no
existence in nature. Such are a few of the significations attached to this
simple word which may be culled from authoritative sources; and if,
leaving terms and theoretical subtleties aside, we turn to facts and
endeavour to gather a meaning for ourselves, by studying the things to
which, in practice, the name of species is applied, it profits us little. For
practice varies as much as theory. Let the botanist or the zoologist
examine and describe the productions of a country, and one will pretty
certainly disagree with the other as to the number, limits, and
definitions of the species into which he groups the very same things. In
these islands, we are in the habit of regarding mankind as of one
species, but a fortnight's steam will land us in a country where divines
and savants, for once in agreement, vie with one another in loudness of
assertion, if not in cogency of proof, that men are of different species;
and, more particularly, that the species negro is so distinct from our
own that the Ten Commandments have actually no reference to him.
Even in the calm region of entomology, where, if anywhere in this
sinful world, passion and prejudice should fail to stir the mind, one
learned coleopterist will fill ten attractive volumes with descriptions of
species of beetles, nine-tenths of which are immediately declared by his
brother beetle-mongers to be no species at all.
The truth is that the number of distinguishable living creatures almost
surpasses imagination. At least a hundred thousand such kinds of
insects alone have been described and may be identified in collections,
and the number of separable kinds of living things is under estimated at
half a million. Seeing that most of these obvious kinds have their
accidental varieties, and that they often shade into others by
imperceptible degrees, it may well be imagined that the task of

distinguishing between what is permanent and what fleeting, what is a
species and what a mere variety, is sufficiently formidable.
But is it not possible to apply a test whereby a true species may be
known from a mere variety? Is there no criterion of species? Great
authorities affirm that there is--that the unions of members of the same
species are always fertile, while those of distinct species are either
sterile, or their offspring, called hybrids, are so. It is affirmed not only
that this is an experimental fact, but that it is a provision for the
preservation of the purity of species. Such a criterion as this would be
invaluable; but, unfortunately, not only is it not obvious how to apply it
in the great majority of cases in which its aid is needed, but its general
validity is stoutly denied. The Hon. and Rev. Mr. Herbert, a most
trustworthy authority, not only asserts as the result of his own
observations and experiments that many hybrids are quite as fertile as
the parent species, but he goes so far as to assert that the particular
plant 'Crinum capense' is much more fertile when crossed by a distinct
species than when fertilised by its proper pollen! On the other hand, the
famous Gaertner, though he took the greatest pains to cross the
primrose and the cowslip, succeeded only once or twice in several
years; and yet it is a well-established fact that the primrose and the
cowslip are only varieties of the same kind of plant. Again, such cases
as the following are well established. The female of species A, if
crossed with the male of species B, is fertile; but, if the female of B is
crossed with the male of A, she remains barren. Facts of this kind
destroy the value of the supposed criterion.
If, weary of the endless difficulties involved