330 EET. J. T. GTJLICK ON 



pendently transformed. In other words, Independent Natural 

 Selection produces Divergen 'ce. 



Sexual Selection is the exclusive propagation of those better 

 fitted to the sexual constitution of the species through the 

 failure to propagate of the less fitted. In the words of Darwin, 

 " It dej^euds on the advantage which certain individuals have 

 over others of the same sex and species solely in respect of 

 reproduction." * It is the form of Eefiexive Selection which has 

 received Darwin's attention, and is consequently familiar to all. 

 There are, however, certain points that need to be empha- 

 sized. 



This is the principle in accordance with which correspondence 

 is secured between the external characteristics and the sexual 

 instincts of a species, and also betAveen the instincts of the two 

 sexes, in as far as they relate to reproduction. This result is 

 secured partly by the failure to propagate of those whose powers 

 of attraction and conqiiest do not reach the standard demanded 

 by the instincts of the other sex, and partly by the failure of 

 those whose instincts diverge too widely from the typical charac- 

 teristics of the other sex. Per example, on the highlands of 

 jS^oi'th China I have observed a species of creeping cricket of the 

 genus Bradypliorus, the male of which calls the female by a sharp 

 stridulation, to which the female responds by approaching the 

 male and finally climbing upon his back. Now we can well 

 understand that the call of the male has been brought to its 

 present shrill, penetrating perfection through the failure to attract 

 mates in the case of males that were but feebly endowed ; but it 

 is equally certain that those females whose sluggish instincts 

 have been capable of responding only to an unusually intense 

 call have, for the most part, failed of leaving off'spring, and, if 

 any have been so unreasonable as to wait for the male to seek 

 them out, they have, doubtless, perished without perpetuating 

 their perverted instincts. If my view is correct, the change 

 producing divergent sexual characteristics may be either in the 

 instinct, or in the characters with which the instinct is correlated. 

 It seems probable that in the vast majority of cases the more 

 strongly divergent forms have been reached by a multitude of 

 deviations alternating between the psychical and the physiolc- 



* ' Descent of Man,' 3rd page of Chap. VIII. 



