98 
ON THE ADVANTAGE 
Chap. IV. 
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 in this very 
genus, which seems to have a special contrivance for 
self-fertilisation, it is well known that if 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 0. C. Sprengel and from my own observations, which 
eflectually 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 
placing pollen from one flower on the stigma of another, 
I raised plenty of seedlings ; and whilst another species 
of Lobelia growing close by, which is visited by bees, 
seeds freely. In very many other cases, though there 
