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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"

(9/9.
'Jenaische Zeitschr. fur Naturwiss' B. 7 1872 page 22 and 1873 page
441.) Several plants were raised from these seeds and kept in the
hothouse. They produced flowers very early in the spring, and twenty of
them were fertilised, some with pollen from the same flower, and some
with pollen from other flowers on the same plants; but not a single
capsule was thus produced, yet the stigmas twenty-seven hours after the
application of the pollen were penetrated by the pollen-tubes. At the
same time nineteen flowers were crossed with pollen from a distinct
plant, and these produced thirteen capsules, all abounding with fine
seeds. A greater number of capsules would have been produced by the
cross, had not some of the nineteen flowers been on a plant which was
afterwards proved to be from some unknown cause completely sterile with
pollen of any kind. Thus far these plants behaved exactly like those in
Brazil; but later in the season, in the latter part of May and in June,
they began to produce under a net a few spontaneously self-fertilised
capsules. As soon as this occurred, sixteen flowers were fertilised with
their own pollen, and these produced five capsules, containing on an
average 3.4 seeds. At the same time I selected by chance four capsules
from the uncovered plants growing close by, the flowers of which I had
seen visited by humble-bees, and these contained on an average 21.


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