As both these tables relate to the fertility of flowers fertilised by
pollen from another plant and by their own pollen, they may be
considered together. The difference between them consists in the
self-fertilised flowers in Table 9/G, being produced by self-fertilised
parents, and the crossed flowers by crossed parents, which in the later
generations had become somewhat closely inter-related, and had been
subjected all the time to nearly the same conditions. These two tables
include fifty cases relating to thirty-two species. The flowers on many
other species were crossed and self-fertilised, but as only a few were
thus treated, the results cannot be trusted, as far as fertility is
concerned, and are not here given. Some other cases have been rejected,
as the plants were in an unhealthy condition. If we look to the figures
in the two tables expressing the ratios between the mean relative
fertility of the crossed and self-fertilised flowers, we see that in a
majority of cases (i.e., in thirty-five out of fifty) flowers fertilised
by pollen from a distinct plant yield more, sometimes many more, seeds
than flowers fertilised with their own pollen; and they commonly set a
larger proportion of capsules. The degree of infertility of the
self-fertilised flowers differs extremely in the different species, and
even, as we shall see in the section on self-sterile plants, in the
individuals of the same species, as well as under slightly changed
conditions of life.
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