162 MR. C. N. BARKER 



white cellular spot of the forewing. It appears that this 

 cellular spot varies in size amongst the different geo- 

 grapliical races of P. dardcuius. P. dardanus, as it oc- 

 curs in Xatalj differs as regards the size and shape of this 

 spot enormoush', and it (the spot) is sometimes alto 

 gether absent. Whatever may occur in the generality of 

 cases of transmission, Prof. Poulton, on Plate I of his 

 paper, "Mimicry, Mutation .and Mendelism " (Bedrock, 

 April, 11)13), gives the photos of a female hippocoon and 

 her offspring, in which the only example of this form 

 differs materially as regards the cellular spot and other 

 details from the parent. In the extremely interesting 

 discussions as to how the two wcmderful '^ mimetic " 

 female forms of Papilio jmlytes were evolved, the ex- 

 pianation that claims that they were produced in all 

 their wonderful mimetic details by a sudden '^ mutation '^ 

 seems to me preposterous. The utmost I should feel in- 

 clined to agree to is what has been conceded by Prof. 

 Poulton, '' that a large variation may arise suddenly, no 

 one ever doubted, but not many naturalists will accept 

 the view that a complex pattern of many elements re- 

 sembling the corresponding elements in an entirely dif- 

 ferent species could spring into existence as a whole and 

 complete in all its details" (Bedrock, page 30G). 



I am quite unable to understand Prof. Poulton's ex- 

 planation of the reason for the existence " of two jnime- 

 tic forms in a butterfly that remains dominant, Avhen 

 the models are absent or excessively rare'*' (Bedrock, 

 page 310). I have always clung to the formula that na- 

 tural selection only acts in cases in which its action is 

 for the betterment of conditions that make for the con- 

 servation of species. Papilio pohjfcs, whether the models 

 are absent or present, is equally well able to maintain 

 its numbers unimpaired. The only reasonable inference, 

 that I am able to understand, is that of Prof. Pimnelt 

 that " natural selection is non-existent in so far as con- 

 cerns the relation of the mimetic to the non -mimetic 

 females of Papilio poli/tcs^' (Bedrock, page 158). 



