24 THE KVOLUTION OF COLOUR IN LEPIDOPTERA. 



though remaining under the same conditions as the others 

 that did not change, began to change colour later on be- 

 coming a waxlike white without my being able to trace 

 the cause thereof. Exactly in the same manner I saw from 

 a certain number of green pupae of Danais Genutia Cram, 

 after a while some becoming pale rose-coloured and the 

 rest remaining green. More similar facts have always kept 

 me from saying much as yet about the results obtained 

 in the matter by other authors especially by Poulton, though 

 many a time I have made observations perfectly agreeing 

 with theirs. 1 thought it prudent to remain on the reserve. 

 Neither do I think it impossible that a hereditary colour- 

 evolution should exist in the pupae, though it could not 

 be traced as yet. In that case the above named action pro- 

 bably ought to be considered principally as a mere stimulus, 

 and so the colour-polymorphism must be here also the 

 expression of stadia in a proceeding course of colour-evo- 

 lution. It attracted my special attention to hear from Mr. 

 Bordage that he had obtained pupae not like normal ones, 

 uniformly polished, looking like gold or silver, but with 

 dark brown stripes and spots on the metallic hue, by breeding 

 caterpillars of Euploea Goudoti Bsd. in complete darkness. 

 While indeed the pupa of Euploea Midamus L. in Java 

 always uniformly has that same golden or silvery hue, the 

 pupa of Euploea leucostictos Gmel. in that country always 

 has such brown spots or stripes on the metallic hue, so 

 that the abnormal condition gives birth in Euploea Goudoti 

 Bsd. to what in the nearly related Euploea leucostictos Gmel. 

 still or already appears as normal. With all this, as already 

 said, one will have to reckon seriously when judging of 

 the eventual answers to the prize-question. 



The Hague, September 1899. 



Notes from the Leyden Museum, Vol. XXII. 



