...OMIT 1866 1869 1872 |
that close interbreeding lessens fertility, and, 1859 1860 1861 |
on the
one one 1866 1869 1872 | other 1859 1860 1861 |
hand hand 1866 1869 1872 | hand, 1859 1860 1861 |
that an occasional cross with a distinct individual or variety increases
the vigour and fertility of the offspring, and on the other hand that very close interbreeding lessens their vigour and fertility, the vigour and fertility of the offspring, and on the other hand that very close interbreeding lessens their vigour and fertility, 1866 1869 1872 |
fertility, 1859 1860 1861 |
that I cannot doubt
the correctness of this
conclusion. conclusion. 1872 |
almost universal belief amongst breeders. 1859 1860 1861 1866 1869 |
Hybrids are seldom raised by experimentalists in great numbers; and as the parent-species, or other allied hybrids, generally grow in the same garden, the visits of insects must be carefully prevented during the flowering
season; season; 1872 | season: 1859 1860 1861 1866 1869 |
hence
hybrids, hybrids, 1872 | hybrids 1859 1860 1861 1866 1869 |
if left to themselves, will if left to themselves, will 1872 |
will 1859 1860 1861 1866 1869 |
generally be
fertilised during each generation by
pollen from the same flower; and pollen from the same flower; and 1872 |
their own individual pollen; and I am convinced that 1859 1860 1861 |
their own individual pollen; and 1866 1869 |
this would
probably be probably be 1866 1869 1872 | be 1859 1860 1861 |
injurious to their fertility, already lessened by their hybrid origin. I am strengthened in this conviction by a remarkable statement repeatedly made by Gärtner, 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
from from 1866 1869 1872 | of 1859 1860 1861 |
manipulation, sometimes decidedly increases, and goes on increasing. Now, in
the process of artificial the process of artificial 1866 1869 1872 |
artificial 1859 1860 1861 |
fertilisation, fertilisation, 1866 1869 1872 | fertilisation 1859 1860 1861 |
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
often on often on 1866 1869 1872 | on 1859 1860 1861 |
the same plant, would be thus effected. Moreover, whenever complicated experiments are in progress, so careful an observer as Gärtner would have castrated his hybrids, and this would have
ensured ensured 1869 1872 | insured 1859 1860 1861 1866 |
in each generation a cross with
....... 1866 1869 1872 | the 1859 | a 1860 1861 |
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
an an 1869 1872 | the 1859 1860 1861 1866 |
increase of fertility in the successive generations of
artificially
fertilised hybrids, hybrids, 1869 1872 | hybrids 1859 1860 1861 1866 |
in contrast with those spontaneously self-fertilised, may, as in contrast with those spontaneously self-fertilised, may, as 1869 1872 |
may, 1859 1860 1861 1866 |
I
believe, be accounted for by
too close too close 1866 1869 1872 | close 1859 1860 1861 |
interbreeding
having been avoided. |