132 THE PROBLEM OF EVOLUTION 



* Father Wasmann has also referred to the advance 

 made by Darwinism or the theory of selection, 

 but he says that he believes this advance will event- 

 ually lead to the establishment of quite a different 

 theory. It is true that the theory has advanced, 

 but unfortunately Father Wasmann has failed to 

 perceive in what direction, otherwise he would have 

 known that his amical selection, the theory which 

 he considers he has established in opposition to 

 that of selection, and which led him to deny the 

 universal applicability of the theory of selection, 

 was thoroughly explained twenty years ago, accord- 

 ing to the principles of the theory of selection. It 

 is certain that no logical contradiction exists, and 

 that is all with which we are now concerned.' 



I subsequently asked Professor Dahl to what 

 work he had referred in these words. He 

 kindly informed me that he had been refer- 

 ring to his ' Versuch einer Darstellung der 

 psychischen Vorgange in den Spinnen' (An 

 Attempt to explain the Psychical Processes 

 in Spiders), which is the second article in the 

 Quarterly Journal of Scientific Philosophy. 

 Avenarius ix. (1885), pp. 162-190. In the third 

 section of this article Dahl speaks of aesthetic 

 sensations (p. 184 et seq.) 9 and discusses the 

 sexual selection among spiders, which has given 

 rise to definite characteristics possessed by the 

 males (excessive development of the eyes) 



