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Wallace, Alfred Russel, 1823-1913

"Darwinism (1889)"

" I must
again refer my readers to my third chapter for the proof that such
simultaneous variability is not an assumption but a fact; but, even
admitting this to be proved, the problem is not altogether solved, and
there is so much misconception regarding variation, and the actual
process of the origin of new species is so obscure, that some further
discussion and elucidation of the subject are desirable.
In one of the preliminary chapters of Mr. Seebohm's recent work on the
_Charadriidae_, he discusses the differentiation of species; and he
expresses a rather widespread view among naturalists when, speaking of
the swamping effects of intercrossing, he adds: "This is unquestionably
a very grave difficulty, to my mind an absolutely fatal one, to the
theory of accidental variation." And in another passage he says: "The
simultaneous appearance, and its repetition in successive generations,
of a beneficial variation, in a large number of individuals in the same
locality, cannot possibly be ascribed to chance." These remarks appear
to me to exhibit an entire misconception of the facts of variation as
they actually occur, and as they have been utilised by natural selection
in the modification of species.


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