of all, we have to state that the selection
theory no longer enjoys that protection which the descent and evolution
theories can justly claim, against the main objection, mentioned in Chap.
III, Sec. 1, to all the ideas of descent, development and selection. That main
objection is the permanence of species, observed through thousands of
years; and the defense with which the descent and evolution theories
successfully weaken it, is the statement of the fact that, since man
appeared, no new species has originated, and that therefore the principle
of the generation of species seems to have come to a stand-still. Now this
fact is no longer in favor of the selection theory, but directly repugnant
to it. For the selection theory expressly declares the origin of species
through agencies that are all active still, and, therefore, if they really
suffice to explain the origin of species, would not only have to generate
new species, {102} but also to develop _all_ the existing species. All
those circumstances which, according to the selection theory, have led to
change of species, are just as active to-day as they are supposed to have
been from the beginning of organic life; and the effect which we observe is
not change but permanence of species. The individuals still have individual
qualities; they still have the tendency to inherit, in addition to the
qualities of the species, those of the individual; the individuals still
change their abode, and therewith also their conditions of life; a natural
selection still takes place in the struggle for existence; and what is the
result? From an observation stretching over thousands of years, we find
nowhere an effect of natural selection going farther than alterations in
growth and color and purely external changes in form. All the dispositions
of organisms and their reciprocal action aim not at increasing the
individual differences, but at reducing them to the average character of
the species. When the species change their abode or their conditions of
life, they either perish or remain constant; at least, with the exception
of the slight modifications before mentioned. Even those alterations which
artificial breeding produces, have a tendency to return to the original
species: as soon as cultivated plants and domestic animals are left to
themselves, they run wild, _i.e._, they reassume their original qualities.
Even the bastard-formations either cease to be fertile, or, remaining
fertile,