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Darwin, Charles, 1809-1882

"On the Origin of Species By Means of Natural Selection, or, the Preservation of Favoured Races in the Struggle for Life"

I am
strengthened in this conviction by a remarkable statement repeatedly
made by Gartner, namely, that if even the less fertile hybrids be
artificially fertilised with hybrid pollen of the same kind, their
fertility, notwithstanding the frequent ill effects of manipulation,
sometimes decidedly increases, and goes on increasing. Now, in
artificial fertilisation pollen is as often taken by chance (as I know
from my own experience) from the anthers of another flower, as from
the anthers of the flower itself which is to be fertilised; so that a
cross between two flowers, though probably on the same plant, would be
thus effected. Moreover, whenever complicated experiments are in
progress, so careful an observer as Gartner would have castrated his
hybrids, and this would have insured in each generation a cross with
the pollen from a distinct flower, either from the same plant or from
another plant of the same hybrid nature. And thus, the strange fact of
the increase of fertility in the successive generations of
ARTIFICIALLY FERTILISED hybrids may, I believe, be accounted for by
close interbreeding having been avoided.
Now let us turn to the results arrived at by the third most
experienced hybridiser, namely, the Honourable and Reverend W.
Herbert. He is as emphatic in his conclusion that some hybrids are
perfectly fertile--as fertile as the pure parent-species--as are
Kolreuter and Gartner that some degree of sterility between distinct
species is a universal law of nature.


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