DISCUSSION 133 



which are not of any use, but actually detri 

 mental in the struggle for existence. I find no 

 allusion here to amical selection, which differs 

 from sexual selection, and was advanced by me, 

 not earlier than 1897, as a theory capable of 

 affording an explanation of the development 

 of the true relation in which inquilines stand 

 to their hosts. 1 I cannot therefore under 

 stand how my theory of amical selection 

 was fully explained twenty years ago according 

 to the principles of the theory of selection. 

 Moreover, to discover whether a logical con 

 tradiction exists is not our sole object on this 

 occasion, but we have also to ascertain whether 

 there is an actual discrepancy between the 

 theories of amical and natural selection. 



In the work quoted above, published in 1885, 

 Dahl proved the existence of a similar real 

 discrepancy between sexual and natural selection. 

 To this extent therefore there is a certain like 

 ness between Dahl s earlier and my later work. 

 But it was not the theory of amical selection 

 alone which is supposed to have led me to 

 regard Darwin s theory of selection as merely 

 a subordinate factor. (Cf. my second lecture, 

 pp. 41, etc.) 



Professor Dahl concluded his speech with these 



1 Zur Entwicklung der Instinkte (Development of Instincts) in the 

 Proceedings of the Zoological and Botanical Society, No. 3, pp. 168-183. 

 Vienna, 1897. 



