32 SEXUAL DIMORPHISM 



male selected not be transmitted to his female offspring as 

 well as to the male ? It is true Darwin believes that this 

 has occurred in some instances, but why does it not occur 

 always ? This is a phenomenon with which selection has 

 nothing to do. Wallace maintains that the females require 

 to have dull colours, and to be inconspicuous, in order to 

 escape the notice of enemies when sitting on their ne%ts. 

 But selection, whether of dull-coloured females by the condi- 

 tions of life, or of brilliant and ornamented males by female 

 fastidiousness, only assumes, and does not explain, the inherit- 

 ance of special characters by one sex and not by the other. 



It is with these two special peculiarities of secondary 

 sexual characters that my own arguments are chiefly con- 

 cerned, and I will therefore consider here what attempts have 

 hitherto been made to explain them. 



It cannot be said that Darwin succeeded in explaining the 

 phenomena. In the extent and accuracy of his knowledge, 

 and the perfect impartiality and devotion to truth with which 

 he collected and examined the evidence bearing upon the 

 general problems of structure and evolution, Darwin sur- 

 passed all his predecessors and contemporaries. His detailed 

 and careful examination of the problems of evolution in 

 general, and of sexual dimorphism in particular, was a great 

 and noble work. His treatises form the foundation of our 

 present knowledge on these subjects. But we do not honour 

 him most by maintaining his doctrines and conclusions with- 

 out change. There is no finality in knowledge. It is 

 perfectly true that some new views may be in the wrong 

 direction, may be retrogressive, but progress, further investi- 

 gation of causes, is always possible, and it is no proof of the 

 unsoundness of new conclusions that they go beyond or differ 

 from those of any authority, however great. 



Darwin's chief conclusion concerning the peculiarities of 

 secondary sexual characters which I have mentioned, is that 



