98 ON THE ADVANTAGE Chap. IV. 



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 

 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 

 be no special mechanical contrivance to prevent the 

 stigma of a flower receiving its own pollen, yet, as 



