Alfred Russel Wallace 



nothing to prevent Natural Selection acting on the two 

 sexes as if they were two species. 



5. Your objection that the same protection would to a 

 certain extent be useful to the male, seems to me utterly 

 unsound, and directly opposed to your own doctrine so 

 convincingly urged in the ** Origin,^' ^^ that Natural Selec- 

 tion never can improve an animal heyond its needs. ^^ So 

 that admitting abundant variation of colour in the male, 

 it is impossible that he can be brought by Natural Selec- 

 tion to resemble the female (unless her variations are 

 always transmitted to him)^ because the difference of their 

 colours is to balance the difference in their organisations 

 and habits, and Natural Selection cannot give to the male 

 more than is needed to effect that balance. 



6. The fact that in almost all protected groups the 

 females perfectly resemble the males shows, I think, a 

 tendency to transference of colour from one sex to the 

 other when this tendency is not injurious. 



Or perhaps the protection is acquired because this 

 tendency exists. I admit therefore in the case of con- 

 cealed nests they [habits] may have been acquired for 

 protection. 



Now for the special case. 



7. In the very weak-flying Leptalis both sexes mimic 

 Heliconidse. 



8. In the much more powerful Papilio, Pieris, and 

 Diadema it is generally the female only that mimics 

 Danaida. 



9. In these cases the females often acquire more bright 

 and varied colours than the male. Sometimes, as in Pieris 

 pyrrha, conspicuously so. 



10. No single case is known of a male Papilio, Pieris, 

 Diadema (or any other insect ?) alone mimicking a Danais, 

 etc. 



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