1 857.] OF FLOWERS. 259 



As soon as the idea arose that the offspring of cross- 

 fertilisation is, in the struggle for life, likely to conquer the 

 seedlings of self-fertilised parentage, a far more vigorous 

 belief in the potency of natural selection in moulding the 

 structure of flowers is attained. A central idea is gained 

 towards which experiment and observation may be directed. 



Dr. Gray has well remarked with regard to this central idea 

 (' Nature/ June 4, 1874) : " The aphorism, ( Nature abhors a 

 vacuum/ is a characteristic specimen of the science of the 

 middle ages. The aphorism, ' Nature abhors close fertilisa- 

 tion/ and the demonstration of the principle, belong to our 

 age and to Mr. Darwin. To have originated this, and also 

 the principle of Natural Selection .... and to have applied 

 these principles to the system of nature, in such a manner as 

 to make, within a dozen years, a deeper impression upon 

 natural history than has been made since Linnaeus, is ample 

 title for one man's fame." 



The flowers of the Papilionaceae attracted his attention 

 early, and were the subject of his first paper on fertilisation.* 

 The following extract from an undated letter to Dr. Asa 

 Gray seems to have been written before the publication of 

 this paper, probably in 1856 or 1857 : 



". . . . What ypu say on Papilionaceous flowers is very 

 true ; and I have no facts to show that varieties are crossed ; 

 but yet (and the same remark is applicable in a beautiful way 

 to Fumaria and Dielytra, as I noticed many years ago), I 

 must believe that the flowers are constructed partly in direct 

 relation to the visits of insects ; and how insects can avoid 

 bringing pollen from other individuals I cannot understand. 

 It is really pretty to watch the action of a Humble-bee on 

 the scarlet kidney bean, and in this genus (and in Lathyrtis 



* Gardeners' Chronicle, 1857, founded leguminous paper was done 



p. 725. It appears that this paper in the afternoon, and the conse- 



was a piece of " over-time " work. quence was I had to go to Moor 



He wrote to a friend, " that con- Park for a week." 



S 2 



