( Ixxii ) 



but as meaning ' the mutual approach by two forms to a 

 mean between them,' In Tr. Ent. Soc. 1896, p. 74, he refers 

 to his conception as ' a kind of give-and-take arrangement, in 

 consequence of which two or more inedible forms may hasten 

 the assimilative process by imitating each other ; ' and of 

 course such hastening can only take place when the approach 

 is simultaneous. In Tr. Ent. Soc. 1897, p. 324, we are informed 

 that ' the benefit of Miillerian Association being mutual, there 

 is a distinct reason . . . for the model to help on the process 

 of assimilation by itself advancing to meet the mimic ' (the 

 italics are mine). But in order that there may be no 

 possibility of a misapprehension Dr. Dixey in the same paper 

 (p. 328) gives a very precise definition as to what we are to 

 understand when he uses his term Reciprocal Mimicry. This 

 expression, he says, ' is meant to convey, besides the general 

 idea of convergence, the special information that in the cases 

 to which the term is applied, the convergence is brought about 

 not hy the simple imitation of one form by another, but by the 

 interchange of features between forms and their consequent 

 simultaneous approach to an intermediate position ' (the 

 italics are mine). Now unless we are to interpret words in a 

 distorted sense, it seems to me that the above passages must 

 assuredly convey the definite idea that Reciprocal Mimicry 

 involves the conception of a mutual simultaneous approach on 

 the part of two species. Indeed, from the last-quoted 

 definition, we may legitimately infer, that whatever he may 

 think now, Dr. Dixey then considered that simultaneous 

 approach was the natural consequence of that give-and-take 

 interchange which his hypothesis postulates ; and the whole 

 internal evidence in his papers is in accord with that view. 



"Then as to the claim that Alternating Mimicry is 

 practically the same thing as Reciprocal Mimicry. This is a 

 statement which I am entirely unable to accept. Throughout 

 Dr. Dixey's writings I can find no trace whatever of the 

 conception of Alternating Minicry as I have defined it above. 

 It has been seen that this conception is based entirely on the 

 view that the relative number of individuals is the most 

 important factor in determining the direction of the mimetic 

 approach between any two species of equal inedibility. Yet 



