224 ON THE ORIGIN OF SPECIES 



be artificially fertilised with hybrid pollen of the same 

 kind, their fertility, notwithstanding the frequent ill 

 effects of manipulation, sometimes decidedly increases, 

 and goes on increasing. Now, in artificial fertilisation 

 pollen is as often taken by chance (as I know from my 

 own experience) from the anthers of another flower, as 

 from the anthers of the flower itself which is to be 

 fertilised ; so that a cross between two flowers, though 

 probably on the same plant, would be thus effected. 

 Moreover, whenever complicated experiments are in 

 progress, so careful an observer as Gartner would have 

 castrated his hybrids, and this would have insured in 

 each generation a cross with a pollen from a distinct 

 flower, either from the same plant or from another plant 

 of the same hybrid nature. And thus, the strange fact of 

 the increase of fertility in the successive generations of 

 artificially fertilised hybrids may, I believe, be accounted 

 for by close interbreeding having been avoided. 



Now let us turn to the results arrived at by the third 

 most experienced hybridiser, namely, the Hon. and 

 Rev. W. Herbert. He is as emphatic in his conclusion 

 that some hybrids are perfectly fertile — as fertile as the 

 pure parent -species — as are Kolreuter and Gartner 

 that some degree of sterility between distinct species is 

 a universal law of nature. He experimentised on some 

 of the very same species as did Gartner. The differ- 

 ence in their results may, I think, be in part accounted 

 for by Herbert's great horticultural skill, and by his 

 having hothouses at his command. Of his many im- 

 portant statements I will here give only a single one as 

 an example, namely, that "every ovule in a pod of 

 Crinum capense fertilised by C. revolutum produced a 

 plant, which (he says) I never saw to occur in a case of 

 its natural fecundation." So that we here have perfect, 

 or even more than commonly perfect, fertility in a first 

 cross between two distinct species. 



This case of the Crinum leads me to refer to a most 

 singular fact, namely, that there are individual plants 

 of certain species of Lobelia and of some other genera, 

 which can be far more easily fertilised by the pollen of 



