[14]
The assertion, that acquired habitudes or instincts, and acquired
structures, are not heritable, any breeder or good observer can
refute.
That "the human mind has become what it is out of a developed
instinct"[15] is a statement which Mr. Darwin nowhere makes, and, we
presume, would not accept. As to his having us believe that individual
animals acquire their instincts gradually,[16] this statement must
have been penned in inadvertence both of the very definition of
instinct, and of everything we know of in Mr. Darwin's book.
It has been attempted to destroy the very foundation of Darwin's
hypothesis by denying that there are any wild varieties, to speak of,
for natural selection to operate upon. We cannot gravely sit down to
prove that wild varieties abound. We should think it just as necessary
to prove that snow falls in winter. That variation among plants cannot
be largely due to hybridism, and that their variation in Nature is not
essentially different from much that occurs in domestication, we could
show, if our space permitted.
As to the sterility of hybrids, that can no longer be insisted upon as
absolutely true, nor be practically used as a test between species and
varieties, unless we allow that hares and rabbits are of one species.
That it subserves a purpose in keeping species apart, and was so
designed, we do not doubt. But the critics fail to perceive that this
sterility proves nothing against the derivative origin of the actual
species; for it may as well have been intended to keep separate those
forms which have reached a certain amount of divergence as those which
were always thus distinct.
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