36 PROC'EHDINGS OF THE 



of crcloiino ami a piecw ol' glazed calico, Tlioiigh pattern and 

 colour were the same the difference in material would yield a 

 somewhat difTeient elYect "*. 



The chemical nature of the colours of butterflies has not been 

 much investigated, except iu the Pierinre, where the white, yellow, 

 orange and red ])igments of the mimics have been shown by 

 Professor F. Gowland Hopkins t to be quite different from those 

 of their models. But even without chemical analysis it is clear 

 that the red of a P/tarmacophaf/iis swallowtail model is very 

 different from the red of its Pajnlio or Cosniodesmus swallowtail 

 n)imic. Thus Professor Punnett, alluding to the quality of the 

 red in the models of the two mimetic Pujiilio polyti'ii femah^s says : 

 " iu both models it is a strong clamorous red suggestive of a 

 powerful aniline dye, whereas such red as occurs in the mimics is 

 a softer and totally distinct colour " %. Hence in these two large 

 classes of mimics, Pierine and Papilionine, the suggestion of 

 identical factors in model and mimic cannot apply. 



A critical examination of other models and their mimics 

 constantly reveals difference under the apparent sameness of 

 colour and pattern. I will mention a single example because it 

 illustrates a physical rather than a chemical difference. Mr. S. 

 A. Neave has told me that the semi-transparent white maikiugs 

 on the black and white species of the African Danaine genus 

 A uiauris appear blue when the insect is on the wing, an effect 

 that can be witnessed by holding an oi)aque black surface beneath 

 the pattern. It is not due to pigment but to the structure of the 

 scales. Such a mimic of Amauris as the liippocoon female of 

 P. dardanus only reproduces this effect very feebly, but the 

 Ui/polimnas (Earalia) co-mimics — e. g, //. anthedon in the west, 

 and II. wahlbergi in the east — exhibit it strongly and in a form 

 somewhat different frotn the model. The blueness is here in pnrt 

 due to a delicate iridescence of the white scales very similar to that 

 of the Amauris, but also to intensely blue marginal scales, absent 

 fron> the Danaine model, hut common to many species of IIiipo- 

 limnas, including the non-mimetic males of mimetic species and 

 both sexes of the huge //. dexithea of Madagascar. The ancestral 

 material of the genus Hiipolimnas has been worked up into the 

 mimetic likeness to a model which does not possess such material 

 at all. 



Assuming, however, for the sake of argument, that mimics 

 exist in which the chpmical and physical causes of colour are 

 identical with those of their models §, it is important to enquire 

 whether Professor Punnett's metaphor of ])atterns on cretonne 

 and calico really help to explain the facts or only to disguise an 

 essential difference. 



* " Mimicry in Butterflies," Cambridge, 1915, p. 148. 



t Proc. Jioij. Sue. Ivii. 1894, p. o ; and Phil. Trans. 189.0, B. p. GOl. 



I "Mimicry in Biitferllies," p. 82. 



§ InsUiuccs doubtless occur where model and mimic are closely allitHl, as in 

 tlie .-Eiiras and Lyaaiuler groups of Pliurmacophayv^ or llie well-known 

 convergent Danaine or Acracine groups. 



