SPIDERS. 335 



connection between the male constitution and bright colours in this case 

 is we cannot tell till the nature of the pigments is known. Wallace has 

 spoken of the frequent brilliancy of males as due to their greater 

 vitality, and refers the relative plainness common in females to their 

 greater need for protection. Darwin referred the greater decorativeness 

 of males to the fact that those which varied in this direction found 

 favour in the eyes of their mates, were consequently more successful in 

 reproduction, and thus tended to entail brilliancy on their male 

 successors. But we naturally ask how the brilliancy began, and how 

 its enhancement is transmitted to males alone. In the " Evolittioii of 

 Sex^^ Professor Geddes and I have recognised that sexual selection 

 may help to establish the brilliancy of males, and that natural selection 

 may help to keep the females plain, but have also sought to associate 

 decorative and other differences between the sexes with the more 

 fundamental qualities of maleness and femaleness. 



I have introduced this subject here, because it affords a pleasant 

 interlude in our systematic survey, and because it serves to illustrate 

 some of the problems of evolution. 



Two American observers, Mr. and Mrs. Peckham, have made a 

 series of studies on the courtship of spiders more careful than any others 

 of the kind. 



They find " no evidence that the male spiders possess greater vital 

 activity ; on the contrary, it is the female that is the more active and 

 pugnacious of the two." They find, " no relation, in either sex, between 

 development of colour and activity ; the Lycosida;, which are among 

 the most active of all spiders, having the least colour development, while 

 the sedentary orb-weavers show the most brilliant hues." " In the 

 numerous cases where the male differed from the female by brighter 

 colours and ornamental appendages, these adornments were not only so 

 placed as to be in full view of the female during courtship, but the 

 attitudes and antics of the male spider at that time were actually such 

 as to display them to the fullest extent possible." "The males were 

 much more quarrelsome in the presence of the females, and to a great 

 extent lost their tendency to fight when the mating season was over." 



The courtship is prolonged and elaborate, the females are not only coy 

 but often savage. The male's love-making is often cut short by his death 

 at the hands or chelicerje of his desired mate. Of course we must be 

 careful not to exaggerate the subtlety of the mental processes involved 

 in the courtship of animals ; we must also beware of regarding it too 

 crudely. 



" The fact that in Attidae the males vie with each other in making an 

 elaborate display, not only of their grace and agility, but also of their 

 beauty, before tfie females ; and that the females, after attentively 

 watching the dances and tournaments which have been executed for 

 their gratification, select for their mates the males which they find most 

 pleasing, points strongly to the conclusion that the great differences in 

 colour and in ornament between the males and females of these spiders 

 are the result of sexual selection." 



It is still, however, quite possible that the colouring and decorations 

 may have arisen as natural outcrops of the male constitution, the charac- 

 teristics of which are by no means limited to greater vitality or activity. 



