228 



THEORIES OE MIMICRY 



selection arrive at corresponding [)oints in their evolu- 

 tionary histor)-, which arc such as to involve Mimetic 

 Resemblance, no one could believe that the similarity to 

 bark or eartli has been produced in the same manner. 

 Tliose who are inclined to accept Sexual Selection as the 

 exi)lanation can onl)- bring the two classes of facts together 

 by supposing that the appearance of some minute portion 

 of the total vegetable or mineral environment has acted 

 as a stimulus and has led one sex to select the other 

 according as it resembled the object in (juestion ; just as 

 Eritz Midler suggested in his letter to Darwin' that 

 mimicry might be due to Sexual Selection stimulated by 

 the appearance of another species. Probably no one is 

 prepared to adopt this view as regards the former class 

 of facts, although Darwin had, as he states in his letter 

 to Meldola ^, considered the possibility of the general tints 

 of the environment intluencini'' the trend of Sexual 

 Selection in this way. 



A fatal objection to an) explanation based on the theory 

 of Sexual Selection is the fact that Protective Resem- 

 blances are so extremely common and perfect in the 

 immature stages of insects. The same objection holds, 

 although with less force, against its use as an explanation 

 of Mimetic Resemblance. 



The conclusion appears inevitable that under no theory 

 except Natural Selection do the various resemblances of 

 animals to their organic and inorganic environments fall 

 together into a natural arrangement and receive a common 

 explanation. On any theory except Natural Selection 

 this can only be brought about by the adoption of extreme 

 views as to the area over which the alternative theor)- 

 is to be applied — views which, at any rate, the great 

 majority of those who are disposed thus to explain Mimetic 

 Resemblance are not prepared to adopt. 



' Sec p. 2 2-',. 



See p. 225. 



