SELECTION 169 



DIFFERENT KINDS OF SELECTION. There 

 of natural selection. 



Tliere is the ordinary "lethal selection,"/ 

 which works hy the discriminate elimination " 

 of t-hg f f ^ fl -t-i-' g fily l^sff "fi** and there is << tepro-*N 

 dyctive selection/' vfaich works through the 

 increase^ and iflflre Affective reproductivity 



of the TTiflrfi fif~ 



Darwin says "natural selection acts by life 

 and death ... by the survival of the fittest 

 and by the destruction of the less well-fitted 

 individuals," he describes lethal selection, 

 and many use the term natural selection in 

 this sense only. But when Weismann says: 

 "Those that are best adapted in colour 

 willsecure the most abundant food andjsdll 

 prnTTfipally. and they will 



thus have a better pro g p^*-^ transmitting 



tl^pi'r ngual nnlnnriT^g fiO th^JT n ff.Sr ri>r> 0i" he 



is obviously describing reprodnptive 



Karl Pearson draws a HIstinrt.iQn between 

 secular 



. 



ral selection, and "periodic selection^" which 

 is. less, p^sily dft pptpr ^ The difference is 

 this: in the ordinary process of natural 



in the mean value of the 



selected cl^arac^er, mustjbe effected from one 

 ge^ora^jofi f-p pnr^fofir But it might also 

 happen that the extreme deviations from the 



