ADAPTIVE COLORATION. 233 



pick out the drones ; chickens also discriminate between drones 

 and workers, eating the former and avoiding the latter. Bum- 

 ble bees and wasps, imitated by many other insects, are them- 

 selves eaten by the kingbird, catbird and several other birds, 

 though it is not known whether the stingless males of these 

 are singled out or not. Such facts as these do not discredit 

 the general theory of mimicry but point out its limits. 



Evolution of Mimicry. Natural selection gives an adequate 

 explanation of the evolution of a mimetic pattern. Before 

 accepting this explanation, however, we must inquire : ( i ) 

 What were the first stages in the development of a mimetic 

 pattern? (2) What evidence is there that every step in this 

 development was vitally useful, as the theory demands that it 

 should be ? These pertinent questions have been answered by 

 Darwin, Wallace, Miiller, Dixey and several other authorities. 



The incipient mimic must have possessed, to begin with, col- 

 ors or patterns that were capable of mimetic development; 

 evidently the raw material must have been present. Now 

 Muller and Dixey in particular have called attention to the 

 fact that many pierids have at least touches of the reds, yellows 

 and other colors that are so conspicuous in the heliconids. 

 More than this, however, Dixey has demonstrated as appears 

 clearly from his colored figures a complete and gradual tran- 

 sition from a typical non-mimetic pierid, Pieris locusta, to the 

 mimetic pierid Mylothris pyrrha, the female of which imitates 

 Heliconius numata. He traces the transition chiefly through 

 the males of several pierid species for the males, though for 

 the most part white (the typical pierid color), " show on the 

 under surface, though in varying degrees, an approach towards 

 the Heliconiine pattern that is so completely imitated by their 

 mates. These partially developed features on the under sur- 

 face of the males [compare Figs. 2 and 3 of Frontispiece] en- 

 able us to trace the history of the growth of the mimetic pat- 

 tern." Starting from Pieris locusta, it is an easy step to 

 Mylothris lypera, thence to M. lorena, and ffbm this to the 

 mimetic M. pyrrha. " Granted a beginning, however small, 



