DARWINISM ATTACKED. 113 



themselves the attention of the females. Seventh, the sec- 

 ondary sexual characters are especially variable. Darwin 

 believed that he had observed certain other conditions to ex- 

 ist which helped make the sexual selection theory probable, 

 but the conditions noted are sufficient if they truly exist. 



Exposed to careful scrutiny and criticism an admira- 



ble and convincing example of such scientific and impar- 



tial criticism is Kramer's analysis of the 



Scrutiny and 



criticism of the secondary sexual characters of European in- 

 theory, sectg ^ fa Qor o f sexua i selection has been 



relieved of all necessity of explaining any but two categories 

 of secondary sexual characters, namely the special weapons 

 borne by males, and the special ornaments and excitatory 

 organs of the males and females. For examination has 

 disclosed the fact that males are not alone 5 in the possession 

 of special characters of attraction or excitation. Regarding 

 these two categories Plate, 8 in his able recent defence of 

 Darwinism, says, "the first part of this theory, the origin of 

 the special defensive and offensive weapons of males through 

 sexual selection is nearly universally accepted. The second 

 part of the theory, the origin of exciting organs has given 

 rise to much controversy. Undoubtedly the presumption 

 that the females compare the males and then choose only 

 those which have the most attractive colours, the finest song, 

 or the most agreeable odour, presents great difficulties, but 

 it is doubtful if it is possible to replace this explanation 

 by a better." Some of these difficulties may be briefly 

 enumerated. 



The theory can be applied only to species in which the 



males are markedly more numerous than the females, or in 



which the males are polygamous. In other 



Males must be % , r i 



more numerous cases there will be a female for each male 

 than females, or w h e ther he be ornamented or not; and the 



be polygamous. 



unornamented males can leave as many progeny 

 as the ornamented ones, which would prevent any cumula- 



