XI.II 



spot, alluded to iis a vestige of the old colour. The others, not subjected to 

 such surroundings, remain light green. A pronounced white environment, too, 

 appears to have a disturbing effect ; hence a few pupae formed against the 

 white gauze turned a dirty white, /. e. somewhat darkened white without green 

 spots. The phenomena noted by Kathariner in the likewise dimorphic pupa 

 of Vanessa Io L. are thus also explained. 



With regard to Danais pupae I am still groping in the dark. The fact 

 mentioned by Poulton that white light induced the production of a few pink 

 coloured pupae of Vanessa Ukticae L. is not without interest in this connection, 

 since there appears to be but little difference between this and the more rosy 

 colour of a portion of these dimorphic Danais pupae. Bordage obtained in 

 this species faint rose, light green, more rarely yellowish-white and sometimes 

 even red pupae; the latter were, probably, infested by parasites and invariably 

 produced imperfectly developed imagines. He thinks that larvae which have 

 pupated against brightly coloured or metallic-lustrous surfaces mostly produce 

 green pupae and against dark coloured surfaces mostly white or rose-coloured 

 ones. With weak illumination against black surfaces and still more in total 

 darkness the rose-coloured and white pupae greatly increased in number. Sub- 

 sequently he found that of a number of pupae placed in golden-lustrous sur- 

 rounding during a day and night ^js had become green and Ys rose and white. 

 This does not, however, shed much light on the subject and certainly does not 

 account for the changes observed by me. My observations in this respect, 

 however, were accidental and were not the result of experiments conducted 

 intentionally with that object in view. In order to be able to form a sound 

 judgment such experiments still require to be carried out. Many other investig- 

 ations also are necessary in this field. We are only at the commencement of 

 the enquiry. In spite of the many experiments conducted in this respect con- 

 cerning the facts, or of their extent and accuracy, incontestably deserving every 

 praise, such as those by Poulton for instance, I believe that, as regards the 

 interpretation of these facts, in general not much of consequence has been 

 contributed. Poulton and others, completel)^ obsessed by the theory of mimicry, 

 endeavour to explain the observed facts simply by mimicry fictions ; even the 

 chromo-photographic interpretation still counts too many adherents. For this 

 reason I can attach but little value to the important study in connection with 

 this subject contained in the work, already referred to, by Wilhelm Petersen. 

 This savant completely adopts this attitude, the phenomenon of colour evolution, 

 and with it every attempt to interpret the colour phenomena on evolutional 

 lines, being wholly foreign to him. The chromo-photographic theory proceeds 

 from the physico-chemical point of view, which is simply based on a vague 



