NATURAL SELECTION SINCE DARWIN 63 



ply logically the principle of selection to all phenom- 

 ena. It fails, however, to explain why an organ 

 may fall below a certain level of development and it 

 does not explain the physiological method causing 

 this retrogression. A theory created later and of 

 which we will speak elsewhere, the theory of germinal 

 selection, filled this want. 



Before we review the various criticisms passed 

 upon the selection theories, we must first examine an 

 important question: is the intraspecific competi-^ 

 tion as general as Darwin thought it to be? Is that - 

 competition a harsh, merciless struggle, a life and 

 death struggle? Many naturalists, Russian scien- 

 tists especially, who have studied regions in which 

 animals have to contend with unfavourable condi- 

 tions, think that this struggle against the environ- 

 ment is much fiercer than any intraspecific struggle. 



A writer, who for theoretical reasons to be men- 

 tioned later, has laid stress on this argument, Kro- 

 potkin, 5 had opportunities to observe animal life in 

 regions where the climate is very severe and the 

 ground barren, namely, Northern Asia. There the 

 life struggle is fierce, but it is directed against nature, ^ 

 which wreaks terrible destruction and constitutes a 

 stronger obstacle to overpopulation than competition 

 among individuals. 



The Russian zoologists, Menzbir and Brandt, 



5 P. Khopotkin. Mutual Aid a Factor in Evolution. 



