THE DARWINIAN THEORY 



remarkable for its extreme amount of variability, 

 from deep reddish-brown to olive or pale yellow, 

 hardly two specimens being exactly alike, but all 

 coming within the range of leaves in various stages 

 of decay. Still more 1 curious is the fact that the 

 paler wings, which imitate leaves most decayed, are 



usually covered with small 

 black dots, exactly resem- 

 bling the minute fungi on 

 decaying leaves." (Fig. 

 22.) This is an extreme 

 case of what is really a 

 general law among butter- 

 flies. The mode in which 

 it is acquired is as follows : 

 At first there is a more 

 or less accidental resem- 

 blance. Large numbers 

 of butterflies are killed by 

 birds, lizards, and other 

 animals, and any whose 

 markings and habits of 

 perching render them less 

 easy to detect will have a 

 better chance of escaping, 

 and so of laying eggs and 

 transmitting their peculiarities to their offspring. 

 This protection becomes, through selection, better 

 from generation to generation, and the imperfectly 

 protected forms are weeded out and eaten. 



Similar examples are found in the Herald and 

 Angle shade moths, which resemble decayed and 



Kallima, showing under surface 

 of wing. 



