196 ORGANIC EVOLUTION CONSIDERED 



If the males and females were equally numerous, 

 as Mr. Darwin thinks they probably are — at least he 

 does not think that there is any great inequality — and 

 if they were all sexually mature at the same time, 

 there would be no occasion for exercising choice, 

 unless, as is sometimes the case, they are polygamous. 

 If they are polygamous, the possession of the females 

 is decided by the law of battle — they follow the old 

 Jacksonian doctrine, "to the victors belong the 

 spoils." 



He thinks, however, that the males are frequently 

 sexually mature in advance of the females, or that 

 the males migrate first, as in the case of some birds, 

 so that the males are thus brought into competition 

 for the females when they arrive. The strongest 

 females would arrive first, and the strongest males, or 

 those that were most favorably colored, or that pos- 

 sessed the greatest power of song, would obtain pos- 

 session of these females and would breed first, and 

 this would give them advantage over the weaker 

 birds that arrived at a later period. 



Mr. Darwin, in " The Descent of Man," has pre- 

 sented many facts as to secondary sexual differences, 

 and has with great ingenuity endeavored to account 

 for these differences mostly by sexual selection and 

 the law of battle. 



It would be entirely beyond the scope of this work 

 to attempt to follow him in detail. I cannot believe, 

 however, that his theories are sufficient to account for 

 the vast number of secondary sexual differences 

 among animals. 



I think that in most cases he presents little, if any, 

 evidence that a choice of males is made by the 

 females, or that the law of battle is so general as to 

 supplement sufficiently the theory of sexual selection. 



I will present a few differences between the sexes 



