70 COLOR-RELATIONS OF CHRYSALIDS 



identical circumstances. Our own Zebra Swallow- 

 tail (Ipliiclides ajax), in which a similar dimor- 

 phism seems to be equally distinct, would serve as 

 a good subject for experiment. 



In concluding his account of his experiments on 

 the Pierinae, Mr. Poulton observes : — 



" It must be remarked that the effect of the colored 

 surroundings upon the dark pigment is, perhaps, the 

 least important part of the changes produced, for there 

 are other consequences which seem to be much deeper 

 in significance and far more difficult to understand. 

 The black pigment patches and minute black dots are 

 cuticular and superficial, while the ground colors are 

 subcuticular and deep-seated ; and in the most brightly 

 colored pupae they are mixed colors due to the existence 

 of different pigmentary (and probably chlorophylloid) 

 bodies present in the different elements and at different 

 depths of the subcuticular tissues of the same pupa. In 

 other pupae no trace of such colors can be seen. Hence 

 we see in these most complex and varied effects of the 

 stimulus provided by the reflected light, which deepen 

 into their permanent pupal condition very many hours 

 after the stimulus has ceased to act, the strongest evi- 

 dence for the existence of a chain of physiological pro- 

 cesses almost unparalleled in intricacy and difficulty, 

 while a theory of comparatively simple and direct photo- 

 chemical changes induced by the stimulus itself without 

 the intervention of such a physiological circle seems 

 entirely inadequate as an explanation of the facts." 



