14 THE EVOLUTION OF SEX. 



a number of detailed criticisms; but his chief contention is, that 

 the beauty of males, and other secondary sexual characters, are 

 not the indirect results of a long process of external selection, 

 but the direct expressions of an internal force. 



The vague suggestions of Mantegazza and others are only 

 of importance as indications of progress towards a fundamental 

 explanation. An obvious objection to the theory of sexual 

 selection, that has been urged by many, is that, while it may 

 in part account for the persistence and progress of secondary 

 characters after they attained a certain degree of development, 

 it does not account for their preservation when weak or incon- 

 spicuous ; in short, the theory may account for the perfecting, 

 but not for the origin of the characters. It may be enough to 

 account for the length and the trimmings of the living garment, 

 but what we wish to know is the secret of the loom. Darwin's 

 account of the evolution of the eyes on the feathers of the Argus 

 pheasant is indeed ingenious and interesting ; but, whatever its 

 probability, it is more important to ask what the predominant 

 brightness of males means as a general fact in physiology. It 

 is of interest, then, to notice the hints thrown out by Mante- 

 gazza, Wallace, and others, directly associating decorativeness 

 with superfluous reproductive material, and the putting on of 

 wedding-robes with the general excitement of the sexually 

 mature organism. From this record of the discussion, it is 

 time however to turn to a more constructive mode of treat- 

 ment. 



