394 



PHYLUM ARTHROPODA 



males are more active, smaller, and more brightly coloured 

 than the females. Darwin referred the greater decorative- 

 ness of the males to the sexual selection exercised by the 

 females. The handsomer variations succeeded in courtship 

 better than their rivals. Wallace referred the greater plain- 

 ness of females to the elimination of the disadvantageously 

 conspicuous in the course of natural selection. There may 

 be truth in both views, but both require to be supplemented 

 by the consideration, in part accepted by Wallace, that the 

 " secondary sexual characters " of both sexes are the natural 

 and necessary expressions of their respectively dominant 

 constitutions. 



The organs consist of : — 



Some peculiarities in reproduction. — Many Insects, such as 

 aphides, silk-moth, and queen-bee, are exceedingly prolific? The queen 

 termite lays thousands of eggs, " at the rate of about sixty per minute " ! 



