THE FACTORS OF EVOLUTION 179 



ceans), trees that grow in Asia and Africa, important to 

 man as the producers of dammar-resin, Gurjun balsam, copal, 

 camphor, etc., were always admired as a case of perfect 

 adaptation for the distribution of the fruits. But according 

 to Kidley's observations the use of these long wings is of very 

 problematic value. If this arrangement in its modern perfect 

 form does not grant any noticeable advantage how can it 

 have originated by natural selection ? It is a fact, unfortunately 

 not to be denied, that there occur in organic nature many pur- 

 poseless and even entirely unsuitable arrangements, a phenomenon 

 which testifies as much against an intelligent Creator as against 

 the validity of the theory of selection. 



The weakest position of the Darwinian doctrine, a redoubt 

 which has now been abandoned by numerous supporters, is the 

 hypothesis of sexual selection. It is a familiar phenomenon that 

 the male and female individuals of a species are greatly differen- 

 tiated in colour as well as structure. We have had several oppor- 

 tunities to refer to these remarkable secondary sex-characters. 

 In many cases the males are furnished with powerful weapons, 

 while the females have none, or possess them in a less developed 

 form. It is only necessary to mention the horns of the roebuck 

 and of cattle, the mighty antlers of the stag, the spurs of the 

 cock, etc. We find, further, that in numerous animals the male 

 is distinguished by a greater beauty, magnificent colour, or striking 

 scent. Who has not, for instance, admired the plumage of the 

 bird-of-paradise, pheasant, and peacock ; the delicate colours and 

 markings on the wings of butterflies ; the remarkable ornamenta- 

 tion on the armour of the rhinoceros-beetle ; the mandibles of the 

 stag-beetle ; the song of the birds and the formation of scent 

 scales in numerous insects? (See fig. 49.) 



As many animals, such as the stag, roedeer, and bull, fight 

 fierce battles for the possession of the females, it might be 

 possible to explain by natural selection, the origin of specific 

 weapons in the male, for they are undoubtedly an advantage 

 and help them to acquire a mate. We may therefore assume 

 that generally the strongest and best-armed males have the 

 best chance to reach maturity and transmit their characters to 

 their progeny. But we are helpless in the face of such 

 phenomena as, for instance, ornamental coloration, which so 



