EXCURSIONS OF AN EVOLUTIONIST 



Man," a book which deals with a subject in one 

 respect even more difficult than the origin of 

 species. In his earlier book Mr. Darwin, with 

 masterly skill, brought together huge masses 

 of facts, and showed their bearings upon a few 

 general propositions relating to the whole or- 

 ganic world. In the " Descent of Man" the 

 problem was different. Propositions of great 

 generality, such as had been established in the 

 " Origin of Species," served here as fundamental 

 principles ; but they had to be supplemented by 

 a consideration of the enormously complex and 

 heterogeneous circumstances which attended the 

 origination of a particular genus. It is enough 

 to say that in the treatment of this arduous prob- 

 lem Mr. Darwin showed no less acuteness and 

 grasp than had been displayed in his earlier work. 

 In connection with this problem of the origin 

 of the human race, Mr. Darwin announced 

 the results of his extensive researches into the 

 subject of sexual selection in the animal king- 

 dom. Some time before this, in his treatise on 

 the " Fertilization of Orchids," published in 

 1862, he had called attention to the interde- 

 pendence between the insect world and the world 

 of flowers. Further research in this direction 

 has made it clear that the beautiful colours and 

 sweet odours of flowers are due to selection on 

 the part of insects. The bright colours and de- 

 licious perfumes attract insects, who come to sip 

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