VARIABLE PKOTECTIVE RESEMBLANCE IN INSECTS 121 



result suggested a trial of black surroundings, from 

 which the strongest effects were at once witnessed : 

 the pupae were as a rule extremely dark, with only 

 the smallest trace, and often no trace at all, of the 

 golden spots which are so conspicuous in the lighter 

 forms. These results suggested the use of white sur- 

 roundings, which appeared likely to produce the most 

 opposite effects. The colours of nearly 150 chrysalides 

 obtained under such conditions were very surprising. 

 Not only was the black colouring matter as a rule 

 absent, so that the pupae were light-coloured, but 

 there was often an immense development of the 

 golden spots, so that in many cases the whole surface 

 of the pupae glittered with an apparent metallic lustre. 

 So remarkable was the appearance that a physicist, to 

 whom I showed the chrysalides, suggested that I had 

 played him a trick and had covered them with gold-leaf. 



These remarkable results led to the use of a gilt 

 background as even more likely to produce and in- 

 tensify the glittering appearance. By this reasoning 

 I was led to make the experiment which had been 

 suggested by Mr. Wood nineteen years before. The 

 results quite justified the reasoning, for a much higher 

 percentage of gilded chrysalides, and still more remark- 

 able individual instances, were obtained among the 

 pupae which were treated in this way. 



The following table shows the results of some ex- 

 periments in which the above-mentioned colours were 

 employed : — 



