Darwin had no opportunity during his lifetime of
considering this question, which was raised later in an acute form by
Weismann.
TO PROF. MELDOLA
_Parkstane, Dorset. January 6, 1897._
My dear Meldola,--The passage to which you refer in the "Origin" (top of
p. 6) shows Darwin's firm belief in the "heredity of acquired
variations," and also in the importance of definite variations, that is,
"sports," though elsewhere he almost gives these up in favour of
indefinite variations; and this last is now the view of all Darwinians,
and even of many Lamarckians. I therefore always now assume this as
admitted. Weismann's view as to "possible variations" and "impossible
variations" on p. 1 of "Germinal Selection" is misleading, because it
can only refer to "sports" or to "cumulative results," not to
"individual variations" such as are the material Natural Selection acts
on. Variation, as I understand it, can only be a slight modification in
the offspring of that which exists in the parent. The question whether
pigs could possibly develop wings is absurd, and altogether beside the
question, which is, solely, so far as direct evidence goes, as to the
means by which the change from one species to another closely allied
species has been brought about. Those who want to begin by discussing
the causes of change from a dog to a seal, or from a cow to a whale, are
not worth arguing with, as they evidently do not comprehend the A, B, C
of the theory.
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