Three of these protected plants became actually
loaded with capsules, especially during the early part of the summer;
and this fact indicates that temperature produces some effect, but the
experiment given in the following paragraph shows that the innate
constitution of the plant is a far more important element. The fourth
plant produced only a few capsules, many of them of small size; yet it
was far more self-fertile than any of the seven plants tried during the
previous year. The flowers on four small branches of this
semi-self-sterile plant were smeared with pollen from one of the other
plants, and they all produced fine capsules.
As I was much surprised at the difference in the results of the trials
made during the two previous years, six fresh plants were protected by
separate nets in the year 1870. Two of these proved almost completely
self-sterile, for on carefully searching them I found only three small
capsules, each containing either one or two seeds of small size, which,
however, germinated. A few flowers on both these plants were
reciprocally fertilised with each other's pollen, and a few with pollen
from one of the following self-fertile plants, and all these flowers
produced fine capsules. The four other plants whilst still remaining
protected beneath the nets presented a wonderful contrast (though one of
them in a somewhat less degree than the others), for they became
actually covered with spontaneously self-fertilised capsules, as
numerous as, or very nearly so, and as fine as those on the unprotected
plants growing near.
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