456 DIRECTIVE FACTORS IN EVOLUTION: 



be pollinated except by a particular kind of insect-visitor. 

 We miss the significance of Natural Selection unless we 

 realise its frequent specificity. Meredith speaks of Nature 

 winnowing " roughly ", and that may sometimes be; but it is 

 also a fact that she often winnows with a meticulous nicety. 

 To sum up. In variation and selection we have, so far 

 as we know, the chief factors of Animate Evolution. The 

 method is theoretically very simple. A move is made and 

 it is tested ; a new idea occurs and it is criticised. But this 

 kind of formal summary of the tactics is quite fallacious. 

 It conceals the heart of the matter, that living creatures 

 with a will to live, with an insurgent self-assertiveness, with 

 a spirit of adventure, with an endeavour after well-being 

 it is impossible to exaggerate the personal aspect of the facts, 

 even if the words which we use in our ignorance may be too 

 metaphorical do trade with time and have commerce with 

 circumstance, as genuine agents, sharing in their own evolu- 

 tion. There is abundant room for sympathetic admiration 

 of the tactics of Animate Nature, though the strategy may 

 and, for science, must remain obscure. 



7. Sexual Selection. 



(a) To illustrate still further the subtlety of the process of 

 Selection we shall now consider how it works in the case 

 of preferential mating. It was primarily in reference 

 to secondary sex-characters that Darwin suggested his theory 

 of sexual selection. Certain variations, e.g.., in the improve- 

 ment of weapons and food-catching apparatus, are favoured 

 by natural selection in the course of the everyday struggle 

 for existence ; in the same way, variations which are advan- 

 tageous in securing mates and consummating sexual repro- 

 duction will be favoured by sexual selection. Darwin began 



