COLOR AND PATTERN IX ANIMALS 425 



a high degree of specialization has been assumed, by nearly all 

 upholders of the use hypotheses, to be natural selection. This 

 agent can account for purposef illness, which is obviously an 

 inherent part of all the hypotheses. And no other suggested 

 agent can. Weismann makes, indeed, of this fact, by inverting 

 the problem, one of the most effective arguments for the potency 

 and "Attmachf of natural selection. He declares that the 

 existence of special protective resemblance, warning colors, 

 and mimicry proves the reality of selection. But it must be 

 asked, while admitting the cogency of much of the argument 

 for natural selection as the efficient cause of high specialization 

 of color and pattern as we have seen it actually to exist, how 

 such a condition as that shown by the mimicking viceroy butter- 

 fly has come to be gradually developed gradual development 

 being confessedly selection's only mode of working. Could the 

 viceroy have had any protection for itself, any advantage at all, 

 until it actually so nearly resembled the inedible monarch as 

 to be mistaken for it? No slight tinge of brow r n on the black 

 and white wings (the typical color scheme of the genus), no 

 slight change of marking, would be of any service in making 

 the viceroy a mimic of the monarch. The whole leap from 

 typical Basilarchia to (apparently) typical Anosia had to be 

 made practically at once. On the other hand, is it necessary 

 for Kallima, the simulator of dead leaves, to go so far as it has 

 in its modification? Such minute points of detail are there 

 as w r ill never be noted by bird or lizard. The simple necessity 

 is the effect of a dead leaf; that is all. Kallima certainlv does 



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that and more. Kallima goes too far and proves too much. 

 And there are other cases like it. Natural selection alone could 

 never carry the simulation past the point of advantage. 



But whatever other factors or agents have played a part in 

 bringing about this specialization of color and pattern, exem- 

 plified by animals showing protective resemblances, warning 

 colors, terrifying manners, and mimicry, naturrl selection has 

 undoubtedly been the chief factor, and the basis of utility 

 the chief foundation, for the development of the specialized 

 conditions. 



