X OBITUARY 297 



must be advantageous in the struggle for exist- 

 ence ; and, the more perfect the action of the 

 mechanism, the greater the advantage. Thus the 

 way lay open for 1 the operation of natural selection 

 in gradually perfecting the flower as a fertilisation- 

 trap. Analogous reasoning applies to the fertil- 

 ising insect. The better its structure is adapted 

 to that of the trap, the more will it be able to 

 profit by the bait, whether of honey or of pollen, 

 to the exclusion of its competitors. Thus, by a 

 sort of action and reaction, a two-fold series of 

 adaptive modifications will be brought- about. 



In 1865, the important bearing of this subject 

 on his theory led Darwin to commence a great 

 series of laborious and difficult experiments on the 

 fertilisation of plants, which occupied him for 

 eleven years, and furnished him with the unex- 

 pectedly strong evidence in favour of the influence 

 of crossing which he published in 1876, under the 

 title of" The Effects of Cross and Self Fertilisation 

 in the Vegetable Kingdom." Incidentally, as it 

 were, to this heavy piece of work, he made the 

 remarkable series of observations on the different 

 arrangements by which crossing is favoured and, 

 in many cases, necessitated, which appeared in the 

 work on "The Different Forms of Flowers in 

 Plants of the same Species" in 1877. 



In the course of the twenty years during which 

 Darwin was thus occupied in opening up new 

 regions of investigation to the botanist and 



