370 DARWINISM AND THE PROBLEMS OF LIFE 



not the adaptations, but the indifferent characters, that 

 were retained in the species. We have already settled 

 these difficulties. 



Hence natural selection with its two postulates is a 

 purely mechanical principle that has never been unsettled 

 by any solid objections. And as we have concluded that 

 it alone accounts for the evolution of living things, we 

 can answer "yes" to the question whether the organic 

 world can be conceived in a purely mechanical sense and 

 whether it can form part of a unified cosmic system. At 

 the same time we admit that it is not yet possible to give 

 a satisfactory explanation of the vital phenomena. 



However, it is only pure natural selection that serves 

 to explain the organic world. All the auxiliary theories 

 are teleological. 



This is true in the first place of sexual selection, or at 

 least of the second category of sexual selection — choice 

 on the part of the female. In this instance we should 

 have an end acting before it is realised. When a 

 musical apparatus was developed in the cricket, for 

 instance, we may very well ask how the females came 

 to be attracted by this particular sound at its first 

 occurrence, while they take to flight at all other sounds ? 

 Even if it is said that curiosity drew them to the new 

 sound, it has not yet been explained how it is that the 

 females yield more readily to the fiddling crickets than 

 to their silent fellows. In every case we have to assume 

 that the chirping sound pleased the females. The same 

 must be done when it is sought to explain any of the 

 other masculine characteristics. The females must have 



