flowers with short pistils fertilised with pollen from the short
stamens, were found to yield more seeds than any other of the
four possible unions, the abortion-theory was knocked on the
head. After some additional experiment, it became evident that
the two forms, though both were perfect hermaphrodites, bore
almost the same relation to one another as do the two sexes of an
ordinary animal. With Lythrum we have the still more wonderful
case of three forms standing in a similar relation to one
another. I afterwards found that the offspring from the union of
two plants belonging to the same forms presented a close and
curious analogy with hybrids from the union of two distinct
species.

In the autumn of 1864 I finished a long paper on 'Climbing
Plants,' and sent it to the Linnean Society. The writing of this
paper cost me four months; but I was so unwell when I received
the proof-sheets that I was forced to leave them very badly and
often obscurely expressed. The paper was little noticed, but
when in 1875 it was corrected and published as a separate book it
sold well. I was led to take up this subject by reading a short
paper by Asa Gray, published in 1858. He sent me seeds, and on
raising some plants I was so much fascinated and perplexed by the
revolving movements of the tendrils and stems, which movements
are really very simple, though appearing at first sight very
complex, that I procured various other kinds of climbing plants,
and studied the whole subject. I was all the more attracted to
it, from not being at all satisfied with the explanation which
Henslow gave us in his lectures, about twining plants, namely,
that they had a natural tendency to grow up in a spire. This
explanation proved quite erroneous. Some of the adaptations