No. 3.J SEXUAL SELEC'I'IOX IN SPIDERS. 138 



slight modifications of fonu, and alii^e poor in species and in 

 individuals." * 



In regard to spiders tiie argument fails entirely. Not only 

 are the plainly colored females more active and pugnacious 

 than the males, but the sedentary Orbvveavers are incompar- 

 ably more gorgeous in color than the quick-running ground 

 spiders. 



Among the Attidoj, where sexual color .is most common, 

 perhaps the most brilliant of all the males is Plabrocestum 

 splendens, which has the body of a splendid iridescent red. 

 According to the theory before us, this should be an especially 

 lively species. The fact is, however, that splendens is the most 

 sluggish and retiring spider that we know of. Even where 

 half a dozen males are brought together each one spins him- 

 self a thick cover of silk, under which he hides. Here he re- 

 mains for days at a time, not even coming out to eat and drink. 

 In the presence of the female, to be sure, he is capable of the 

 liveliest action, but at other times he holds himself hidden and 

 absolutely quiet. 



THIRD PART OF MR. WALLACE'S THEORY : ACTIVITY THE CAUSE 

 OF COLOR AND ACCESSORY PLUMES. 



Let us now look at activity as a cause of ornamentation. 



As Mr. Wallace left his theory in " Tropical Nature " it did 

 not explain the distribution of the sexual colors of the males, 

 and their frequent appearance in certain definite parts of the 

 body. It might be granted that he had made clear the origin 

 -of color in general, but not the sexual ornamentation of the 

 males. This question is taken up in " Darwinism." 



In view of all Mr. Darwin's work in this connection we are 

 surprised at his opening assertion that female selection does not 

 account for the fact that these ornamental appendages appear 

 in a few definite parts of the body, and that " we require some 

 -cause to initiate the development in one part rather than in 

 another." No one has taken greater pains to prove, nor has 

 -any one presented in so masterly a way as Mr. Wallace himself 



' standard Natural History, edited by J. S. Kingsley, Vol. IV., p. 467 



