THE SELECTING POWER OF ENEMIES 61 



factors of specific environments : and must 

 be powerful selecting agents calling forth 

 important corresponding structures. 



One other conclusion that has been arrived at may here 

 be mentioned. 



As has been truly pointed out, the welfare of a species 

 is almost of as much importance to the species' enemy as 

 to the species itself. In spite of this, some naturalists 

 expect to find highly protectively coloured animals almost 

 free from enemies. Were this so, then there would be 

 no selection, there would be nothing to maintain this 

 specialisation, which according to present-day arguments 

 would at once begin to degenerate until its efficacy failed, 

 permitting the enemy to again destroy. 



It seems, therefore, that the most efficient protective 

 coloration can only be maintained by a severe selection 

 by enemies. So only can be produced and maintained 

 other highly specialised characters such as warning 

 coloration. 



One must therefore expect to observe that animals 

 which present a high degree of protective or warning 

 coloration, frequently form food for their predaceous 

 enemies. 



