No. 3.1 SEXUAL SELECTION IN SPIDERS. US 



that their appearance is by no mean.s confined to those areas 

 that have high muscular development. 



If it be admitted that there is no causal relation between 

 high muscular and nervous development and brilliant orna- 

 mentation in eiiher birds or spiders, Mr. Wallace is left with 

 onl}'^ a very incomplete theory of sexual ornamentation, since, 

 without Tyler's hypothesis, the really important point — i. e. the 

 limitation of the ornaments to a few definite parts of the body — 

 is unexplained. Whether the evidence which he offers is 

 enough to prove the relation we leave the reader to decide. 

 For ourselves, when we consider the mass of evidence offered 

 by Mr. Darwin in support of his theory and contrast it with 

 the small amount offered by Mr. Wallace, we are impressed 

 anew with the high value of facts as compared with o[)inions. 



OBJECTION TO MR. WALLACE'S THEORY. 



Even if Mr. Wallace were able to prove the propositions 

 upon which he founds his theory, his view would still be open 

 to the strong objection that under it the bright colors and 

 ornaments of the males are mere by-products, meaning- 

 less and useless, belonging, in fact, to Poulton's non-signifi- 

 cant group. He states, in more than one place, his belief 

 that the possession of ornamental appendages and bright 

 colors in the male is not an important character functionally.* 

 Are, then, all these sexual peculiarities in birds and spiders, 

 plumes, colors, leg-modifications and enlargements and orna- 

 mentation of the falces, to be put into the same category as the 

 color of the bile? If they have any use, we must suppose 

 that it is that of pleasing the female, and that they have 

 arisen through female selection. 



In his review of Mr. Poulton's work on Colors of Animals, 

 Mr. Wallace demurs to the use of the term lesthetic in con- 

 nection with these creatures. We take it that all would agree 

 that the word is unfortunate if any one understands that it is 

 used in its higher sense. Perhaps Allen's suggestion, that we 



* Tropical Nature, pp. 199 and i*10. In tlie latter place lie .states his opinion tliat 

 they may be slightly injurious ; and in Darwinism he says that the plumes of the birds of 

 paradise and the peacock must be injurious rather than beneficial. 



