296 OBITUARY X 



tion. Sprengel's observations had been most 

 undeservedly neglected and well-nigh forgotten ; 

 but Robert Brown having directed Darwin's 

 attention to them in 1841, he was attracted 

 towards the subject, and verified many of Sprengel's 

 statements. (Ill, p. 258.) It may be doubted 

 whether there was a living botanical specialist, 

 except perhaps Brown, who had done as much. 

 If, however, adaptations of this kind were to be 

 explained by natural selection, it was necessary to 

 show that the plants which were provided with 

 mechanisms for ensuring the aid of insects as 

 fertilisers, were by so much the better fitted 

 to compete with their rivals. This Sprengel 

 had not done. Darwin had been attending to 

 cross fertilisation in plants so far back as 1839, 

 from having arrived, in the course of his specu- 

 lations on the origin of species, at the convic- 

 tion "that crossing played an important part 

 in keeping specific forms constant" (I, p. 90). 

 The further development of his views on the 

 importance of cross fertilisation appears to have 

 taken place between this time and 1857, when he 

 published his first papers on the fertilisation of 

 flowers in the " Gardener's Chronicle." If the 

 conclusion at which he ultimately arrived, that 

 cross fertilisation is favourable to the fertility of 

 the parent and to the vigour of the offspring, is 

 correct, then it follows that all those mechanisms 

 which hinder self-fertilisation and favour crossing 



