08 in height. The three tallest of all the self-fertilised plants were
then carefully selected, and their heights were 6 3/8, 5 5/8, and 5 2/8,
averaging 5.75 in height. So that the naturally crossed plants were to
the spontaneously self-fertilised plants in height, at least as much as
100 to 81.
Verbascum thapsus.
The flowers of this plant are frequented by various insects, chiefly by
bees, for the sake of the pollen. Hermann Muller, however, has shown
('Die Befruchtung' etc. page 277) that V. nigrum secretes minute drops
of nectar. The arrangement of the reproductive organs, though not at all
complex, favours cross-fertilisation; and even distinct species are
often crossed, for a greater number of naturally produced hybrids have
been observed in this genus than in almost any other. (3/9. I have given
a striking case of a large number of such hybrids between Verbascum
thapsus and lychnitis found growing wild: 'Journal of Linnean Society
Botany' volume 10 page 451.) Nevertheless the present species is
perfectly self-fertile, if insects are excluded; for a plant protected
by a net was as thickly loaded with fine capsules as the surrounding
uncovered plants. Verbascum lychnitis is rather less self-fertile, for
some protected plants did not yield quite so many capsules as the
adjoining uncovered plants.
Plants of Verbascum thapsus had been raised for a distinct purpose from
self-fertilised seeds; and some flowers on these plants were again
self-fertilised, yielding seed of the second self-fertilised generation;
and other flowers were crossed with pollen from a distinct plant.
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