608 THE DESCENT OF MAN. 



ination of each seed, — and other such events, have all heen or- 

 dained for some special purpose. 



Sexual selection has been treated at great length in this work; 

 for, as I have attempted to show, it has played an important part 

 in the history of the organic world. I am aware that much re- 

 mains doubtful, but I have endeavored to give a fair view of the 

 whole case. In the lower divisions of the animal kingdom, sexual 

 selection seems to have done nothing: such animals are often 

 affixed for life to the same spot, or have the sexes combined in 

 the same individual, or what is still more important, their per- 

 ceptive and intellectual faculties are not sufficiently advanced to 

 allow of the feelings of love and jealousy, or of the exertion of 

 choice. When, however, we come to the Arthropoda and Verte- 

 brata, even to the lowest classes in these two great Sub-Kingdoms, 

 sexual selection has effected much. 



In the several great classes of the animal kingdom, — in mam- 

 mals, birds, reptiles, fishes, insects, and even crustaceans, — the dif- 

 ferences between the sexes follow nearly the same rules. The 

 males are almost always the wooers; and they alone are armed 

 with special weapons for fighting with their rivals. They are 

 generally stronger and larger than the females, and are endowed 

 with the requisite qualities of courage and pugnacity. They are 

 provided, either exclusively or in a much higher degree than the 

 females, with organs for vocal or instrumental music, and v.'ith 

 odoriferous glands. They are ornamented with infinitely diversi- 

 fied appendages, and with the most brilliant or conspicuous col- 

 ors, often arranged in elegant patterns, whilst the females are 

 unadorned. When the sexes differ in more important structures, 

 it is the male which is provided with special sense-organs for 

 discovering the female, with locomotive organs for reaching her, 

 and often with prehensile organs for holding her. These various 

 structures for charming or securing the female are often devel- 

 oped in the male during only part of the year, namely the breed- 

 ing-season. They have in many cases been more or less trans- 

 ferred to the females; and in the latter case they often appear 

 in her as mere rudiments. They are lost or never gained by the 

 males after emasculation. Generally they are not developed in 

 the male during early youth, but appear a short time before the 

 age for reproduction. Hence in most cases the young of both sexes 

 resemble each other; and the female somewhat resembles her 

 young offspring throughout life. In almost every great class a 

 few anomalous cases occur, where there has been an almost com- 

 plete transposition of the characters proper to the two sexes; the 

 females assuming characters which properly belong to the males. 

 This surprising uniformity in the laws regulating the differences 

 between the sexes in so many and such widely separated classes. 



