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. (III, 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, 1t 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 
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