BUTTERFLY-HUNTING BEGINS. 33 



up hastily, opens its wings to the sunshine, 

 and shows itself off at once as a red- streaked 

 beauty in all its glory. It is not difficult to 

 see that the difference of colour in the two 

 sides of its wings must be designed for some 

 special purpose, and that the purpose of the 

 under side is to escape detection, while the 

 purpose of the upper side is to attract atten- 

 tion. 



The protective use of the brown under- 

 wings is very simply explained. The insect 

 must be much exposed to birds and other 

 hostile creatures as it sits still, and so it 

 requires to resemble the ground, leaves, or 

 twigs, on which it usually settles, in order to 

 deceive the eyes of its enemies. To some 

 people it seems that so slight a protection as 

 this could scarcely be of any use to the 

 butterfly. Natural selection, they say, can 

 hardly work upon such petty differences. 

 But to talk so is really to show a misappre- 

 hension of what natural selection rightly 

 means. Every butterfly which is spotted by 



D 



