Thirty flowers on some plants of this
species were crossed and produced twenty-seven capsules, each containing
five seeds; thirty-two flowers on the same plants were self-fertilised
and produced only six capsules, each containing five seeds. As the
number of seeds per capsule is here the same, the fertility of the
crossed and self-fertilised flowers is given in Table 9/F as equal, or
as 100 to 100. But if the flowers which failed to produce capsules be
included, the crossed flowers yielded on an average 4.50 seeds, whilst
the self-fertilised flowers yielded only 0.94 seeds, so that their
relative fertility would have been as 100 to 21. I should here state
that it has been found convenient to reserve for separate discussion the
cases of flowers which are usually quite sterile with their own pollen.
TABLE 9/f.--relative fertility of the flowers on the parent-plants used
in my experiments, when fertilised with pollen from a distinct plant and
with their own pollen. Fertility judged of by the average number of
seeds per capsule. Fertility of crossed flowers taken as 100.
Column 1: Name of plant and feature observed.
Column 2: x, in the expression 100 to x.
Ipomoea purpurea--crossed and self-fertilised flowers yielded seeds as
(about): 100.
Mimulus luteus--crossed and self-fertilised flowers yielded seeds as (by
weight): 79.
Linaria vulgaris--crossed and self-fertilised flowers yielded seeds as:
14.
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