( Ixxi ) 



reply to my criticisms of his hypothesis of Diaposematism, 

 it is obviously impossible for me to make any adequate 

 rejoinder at present. But there is one point to which I 

 should like to reply immediately. When my paper was read 

 in March last, Dr. Dixey in the course of the few remai-ks 

 that he made afterwards stated that I had 'given myself 

 away rather badly ' on one or two points, though the nature 

 of my supposed blunders was in no way indicated. I now 

 learn that the principal point upon which I am supposed to 

 have ' given myself away ' is that I have assumed that it is 

 an essential feature of the hypothesis of Reciprocal Mimicry 

 that the two inedible forms should mimic each other simulta- 

 neously. Now, I understand that this suggestion is repudiated 

 by Dr. Dixey, who further claims that the hypothetical kind 

 of mimicry which I have called Alternating Mimicry (Tr, Ent. 

 Soc. 1908, p. 103) is merely part and parcel of his own 

 hypothesis of Diaposematism. I may here explain that the 

 idea of Alternating Mimicry is based on the supposition that 

 where two inedible species of practically similar distasteful- 

 ness are mimetically associated then the mimetic approach 

 will be in one direction only, and will be determined by the 

 relative numbers of the two forms. If A be numerous 

 and B much less so, then B will mimic A ; and if sulj- 

 sequently through other causes the relative numbers of the 

 two forms became reversed, then B would cease to mimic A, 

 and provided always that the necessary variations arose, A 

 would begin to mimic B. The resulting interchange of 

 characters is what I should call Alternating Mimicry.* Let 

 us now examine what Dr. Dixey has actually said with regard 

 to the nature of the mimetic approach in the case of his 

 Reciprocal Mimicry. In Tr. Ent. Soc. 1894, p. 297, he defines 

 Reciprocal Mimicry as being produced by ' A and B con- 

 verging to a point between them,' and further on the same 

 page describes the process as ' mutual convergence ' (the italics 

 are his). On p. 298, foot-note, he points out specially that he 

 does not use ' convergence ' in Professor Poulton's sense, 

 namely, as signifying the assimilation of one form to another, 



* Strictly speaking, Diaposematism is a term more applicable to this 

 form of Mimicry than to Reciprocal Mimicry. 



