"If the point," he
writes, "were once gained, that among animals and vegetables there
had been, I do not say several species, but even a single one, which
had been produced in the course of direct descent from another
species; if, for example, it could be once shown that the ass was
but a degeneration from the horse--then there is no farther limit to
be set to the power of Nature, and we should not be wrong in
supposing that with sufficient time she could have evolved all other
organised forms from one primordial type." So with use and disuse
and transmission of acquired characteristics generally--once show
that a single structure or instinct is due to habit in preceding
generations, and we can impose no limit on the results achievable by
accumulation in this respect, nor shall we be wrong in conceiving it
as possible that all specialisation, whether of structure or
instinct, may be due ultimately to habit.
How far this can be shown to be probable is, of course, another
matter, but I am not immediately concerned with this; all I am
concerned with now is to show that the germ-cells not unfrequently
become permanently affected by events that have made a profound
impression upon the somatic cells, in so far that they transmit an
obvious reminiscence of the impression to the embryos which they go
subsequently towards forming.
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