Till 



nt and animal use is limited; many more individual* 



a born than can survive; the result is a perpetual 

 n^gle for survival. 



i The n'tt. -i individuals tend to be the ones 

 survive; the battle is to the M in* race is to the 



swift. 



Tin- individuals so selected transmit many of 

 r favorable qualities to their iV-pring by heredity. 



(4) But altli.'ii-li heredity ]'mduces a wonderfully 

 exact copy of tin- pan-nt in tin- child, there is never pre- 

 cise reduplication. There i- latitude for individual vari- 

 ation. If, among the bmumermbk multitudes of indi- 

 vidual variations that may occur, one chances to appear 

 \vh'u-li, no mutter in how slight a degree, gives the in- 

 'dual possessing it advantage in the struggle, that 

 individual is bound to be favored with longer life and 

 larger number of y \\ith survival, in short. 



But the theory of natural selection proposes to ex- 

 plain only those characters which irive advantage in the 

 strugjr!' . It does not explain th nee 



of certain which do not give definite advan- 



tage to their possessors and yet t> nd to persist from 

 generation to generation. Some of these characters, like 

 the brilliant plumage of certain birds (peacock and pea- 

 hen), would seem to be of po-itive disadvantage by 

 makiuir them conspicuous to their enemies. To account 

 these markedly contrasted sex-characters, Darwin 

 advanced the theory of Sexual Selection. He believed 

 that the individuals possessing the brilliant coloring 

 were more attractive to those of the opposite sex and so 

 had a better chance to mate than their fellows of a more 

 sober hue. By the laws of heredity the brilliant plumage 

 was transmit ted, and the less attractive individuals, not 



