A STUDY OF MIMICRY 11 



has been a long one, so that in the case of para- 

 static mimicry, as that form which involves the 

 copying of one's fellows might be termed (or, if 

 one prefers an English term, neighborly mimicry), 

 we may readily presnme far less difference between 

 mocker and mocked when the mimicry between 

 them first began than now exists between the 

 mocked and the normal relatives of the mocker. 

 It is argued, indeed, with great show of reason, 

 that as the resemblance grew stronger the birds 

 became more sharp-sighted, which reflected again 

 on the mimicry, and that thus the final departure 

 from the normal type was intensified ; but this 

 assmnption is not necessary. 



So far we have referred only to the first illustra- 

 tions of mimicry given by Bates, those which pre- 

 sent the simplest, though not the least striking- 

 forms, involving as they do the widest departure 

 of mimetic butterflies from their normal type. 

 Let us glance briefly at some other points. 



A new element enters when we find that neigh- 

 borly mimicry is sometimes confined to a single 

 sex of a butterfly ; that is to say, one sex is of the 

 normal color of its allies, while the opposite sex 

 departs widely therefrom, and is found to resemble 

 closely another and a nauseous butterfly of the 



