2i4 HUXLEY AND NATURAL SELECTION 



' There is a Nice Butterfly (whom we will call A.) who is 

 uncomfortably conscious of being regarded as a delicious tit- 

 bit by every bird or lizard with any pretensions to a palate. 



' There is also a Nasty Butterfly (hereinafter referred 

 to as B.) whom even the least particular lizard or bird 

 will, after a single experience of his peculiar flavour, take 

 uncommonly good care never to touch again. 



' So says A. to himself (or else Nature says it for him — 

 I am too unscientific to know which) : " If I could only 

 make myself look as nasty as B. is, all the birds and 

 lizards would let me alone ! " Which, by patience and 

 perseverance, A . gradually contrives to do. 



' Well, I will admit that this idea of A.'s is not without 

 a showy ingenuity, even if it is wanting in true reciprocity 

 and consideration for B.'s interests. What I fail to see is 

 that, from A.'s point of view, it is really such a very 

 masterly stratagem.' 



The writer then goes on to point out that when the 

 enemy comes across A before B all the advantages as 

 he conceives them would be lost, while B itself would be 

 endangered in spite of its nauseous qualities. 



Omitting the allusions to conscious imitation, which, 

 although expressing a common popular error, are clearly 

 not intended to be taken seriously, the whole argument 

 is a fair presentation and criticism of Batesian mimicry 

 It only fails to do justice to this hypothesis in one respect, 

 — the mimics are represented as relatively common, so 

 common indeed that it is assumed to be a matter of 

 indifference whether A or B be met with first. But 

 Bates assumed that the nauseous models are hundreds 

 or even thousands of times as abundant as their palatable 

 mimics. It is true, however, that the mimics are often 

 extremely abundant, but then it is probable that such cases 

 are to be explained by the alternative theory of Fritz 

 Muller. As a matter of fact, the title of the exhibit, 

 ' Reciprocal Advantage ', is conclusive evidence that it 

 was this theory, and not that of Bates, which was being 

 illustrated. In fact both A and B are supposed to be 

 nauseous : then if an enemy eats B first it will be warned 

 against the appearance of A as well as B ; if it eats A 



