pea-family; but in several, perhaps in all, such flowers, there is a
very curious adaptation between the structure of the flower and the
manner in which bees suck the nectar; for, in doing this, they either
push the flower's own pollen on the stigma, or bring pollen from another
flower. So necessary are the visits of bees to papilionaceous flowers,
that I have found, by experiments published elsewhere, that their
fertility is greatly diminished if these visits be prevented. Now, it
is scarcely possible that bees should fly from flower to flower, and not
carry pollen from one to the other, to the great good, as I believe,
of the plant. Bees will act like a camel-hair pencil, and it is quite
sufficient just to touch the anthers of one flower and then the stigma
of another with the same brush to ensure fertilisation; but it must not
be supposed that bees would thus produce a multitude of hybrids between
distinct species; for if you bring on the same brush a plant's own
pollen and pollen from another species, the former will have such a
prepotent effect, that it will invariably and completely destroy, as has
been shown by Gartner, any influence from the foreign pollen.

When the stamens of a flower suddenly spring towards the pistil, or
slowly move one after the other towards it, the contrivance seems
adapted solely to ensure self-fertilisation; and no doubt it is useful
for this end: but, the agency of insects is often required to cause the
stamens to spring forward, as Kolreuter has shown to be the case with
the barberry; and curiously in this very genus, which seems to have a
special contrivance for self-fertilisation, it is well known that if
very closely-allied forms or varieties are planted near each other, it
is hardly possible to raise pure seedlings, so largely do they
naturally cross. In many other cases, far from there being any aids for
self-fertilisation, there are special contrivances, as I could show
from the writings of C. C. Sprengel and from my own observations, which
effectually prevent the stigma receiving pollen from its own flower: for
instance, in Lobelia fulgens, there is a really beautiful and
elaborate contrivance by which every one of the infinitely numerous
pollen-granules are swept out of the conjoined anthers of each flower,
before the stigma of that individual flower is ready to receive them;
and as this flower is never visited, at least in my garden, by insects,
it never sets a seed, though by