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From this extreme degree of sterility we have self-fertilised hybrids producing a greater and greater number of seeds up to perfect fertility.
For these plants have been found to yield seed to the pollen of a distinct species, though quite sterile with their own pollen, notwithstanding that their own pollen was found to be perfectly good, for it fertilised distinct species. So that certain individual plants and all the individuals of certain species can actually be hybridised much more readily than they can be self-fertilised!
Even with those plants in which the sexes are separate, the male flowers are generally mature before the female. As first shewn by C.K. Sprengel, many hermaphrodite plants are dichogamous; that is, their male and female organs are not ready at the same time, so that they cannot be self-fertilised.
Nevertheless these facts show on what slight and mysterious causes the lesser or greater fertility of species when crossed, in comparison with the same species when self-fertilised, sometimes depends. The practical experiments of horticulturists, though not made with scientific precision, deserve some notice.
We are reminded by this latter fact of the extraordinary case of Hippeastrum, Lobelia, &c, which seeded much more freely when fertilised with the pollen of distinct species, than when self-fertilised with their own pollen.
From this extreme degree of sterility we have self-fertilised hybrids producing a greater and greater number of seeds up to perfect fertility.
Rubrinervis is a mutation from Lamarckiana, chiefly distinguished by red midribs in the leaves and red stripes on the sepals. When propagated from self-fertilised seed it produced about 95 per cent. of offspring with the same characters, and the remaining 5 per cent. mutants, one of which was laevifolia which had been found by De Vries among plants growing wild at Hilversum.
For these plants have been found to yield seed to the pollen of a distinct species, though quite sterile with their own pollen, notwithstanding that their own pollen was found to be perfectly good, for it fertilised distinct species. So that certain individual plants and all the individuals of certain species can actually be hybridised much more readily than they can be self-fertilised!
We are reminded by this latter fact of the extraordinary case of Hippeastrum, Lobelia, etc., which seeded much more freely when fertilised with the pollen of distinct species, than when self-fertilised with their own pollen.
From this extreme degree of sterility we have self-fertilised hybrids producing a greater and greater number of seeds up to perfect fertility.
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