( Ixxiii ) 



this question of relative numbers has been entirely neglected 

 by Dr. Dixey in dealing with his supposed cases of mimetic 

 interchange. How can he explain this strange omission if 

 Alternating Mimicry was really an essential portion of his 

 hypothesis as he suggests 1 It is difficult also to understand 

 how- he could have made the following assertion : ' It seems 

 hitherto to have been taken for granted that a dominant form 

 will attract or retain other species within its own sphere of 

 influence, without being itself attracted in return ; whereas 

 the fact is, as we have seen, that each member of an inedible 

 association has more or less influence upon all the rest ' (op. 

 cit. 1897, p. 327). Now I do not at all accept the validity of 

 this theoretical ' fact,' and it is quite at variance with the 

 principle which underlies the suggestion of Alternating 

 Mimicry. One final quotation will suffice. We have been 

 told that ' the most complete intermingling of characters 

 given and taken on both sides may be expected when two 

 species meet on equal terms, neither being strong enough to 

 predominate over the other' (I. c). This then is considered 

 to be the optimum condition for the production of Reciprocal 

 Mimicry, and it is obvious that any possibility of Alternating 

 Mimicry is entirely excluded ; indeed, from the standpoint of 

 that hypothesis there would be no mimicry at all in such a 

 case, because the species would be in what I have called a 

 state of mimetic equilibrium. It is also obvious that if 

 mimetic approach be possible between two such species, then 

 it must necessarily be simultaneous. I therefore feel entitled 

 to claim that I was fully justified in asserting simultaneous 

 approach to be an essential feature of the hypothesis of 

 Reciprocal Mimicry, and that I was also justified in treating 

 Alternating Mimicry as a conception differing radically from 

 it." 



