ed from Gandavensis, a well-known old hybrid, said to be
descended from _G. Natalensis_ by the pollen of _G.
oppositiflorus_.[321] Mr. Rawson, after repeated trials, found that
none of the varieties would set seed with their own pollen, although
{140} taken from distinct plants of the same variety, which had, of
course, been propagated by bulbs, but that they all seeded freely with
pollen from any other variety. To give two examples: Ophir did not
produce a capsule with its own pollen, but when fertilised with that of
Janire, Brenchleyensis, Vulcain, and Linne, it produced ten fine
capsules; but the pollen of Ophir was good, for when Linne was
fertilised by it seven capsules were produced. This later variety, on
the other hand, was utterly barren with its own pollen, which we have
seen was perfectly efficient on Ophir. Altogether, Mr. Rawson, in the
year 1861, fertilised twenty-six flowers borne by four varieties with
pollen taken from other varieties, and every single flower produced a
fine seed-capsule; whereas fifty-two flowers on the same plants,
fertilised at the same time with their own pollen, did not yield a
single seed-capsule. Mr. Rawson fertilised, in some cases, the
alternate flowers, and in other cases all those down one side of the
spike, with pollen of other varieties, and the remaining flowers with
their own pollen; I saw these plants when the capsules were nearly
mature, and their curious arrangement at once brought full conviction
to the mind that an immense advantage had been derived from crossing
these hybrids.

Lastly, I have heard from Dr. E. Bornet, of Antibes, who has made
numerous experiments in crossing the species of Cistus, but as not yet
published the results, that, when any of these hybrids are fertile,
they may be said to be, in regard to function, dioecious; "for the
flowers are always sterile when the pistil is fertilised by pollen
taken from the same flower or from flowers on the same plant. But they
are often fertile if pollen be employed from a distinct individual of
the same hybrid nature, or from a hybrid made by a reciprocal cross."

_Conclusion._--The facts just given, which show that certain plants are
self-sterile, although both sexual elements are in a fit state for
reproduction when united with distinct individuals of the same or other
species, appear at