THE CANADIAN ENTOMOLOGIST 163 



by transmitted light. Gold leaf appears yellow by reflected light, 

 and green by transmitted light. A solution of chlorophyll in 

 alcohol appears a beautiful green colour by transmitted light, 

 but blood-red by strong reflected light. Aniline dyes show this 

 property also, and hence it is quite possible that if there is colouring 

 matter in the scales, that it may also show complimentary colours 

 when viewed by reflected and transmitted light. Now, the light 

 scales always appear more or less distinctly yellow by transmitted 

 light, and yellow is complimentary to blue. If now such an 

 assemblage of loose and scattered scales be viewed by a microscope 

 with reflected illumination and against a dark or quite black 

 background, it will be at once seen, provided the illuminating light 

 is white or nearly so, that the light scales are strongly tinted with 

 blue and often are very blue. The dark ones on the contrary 

 remain dark and show practically no colour except occasional 

 metallic flashes tinted either blue, green or red. Hence we see 

 here that the light transparent scales have undoubtedly the power 

 to appear blue quite independently of whether they are super- 

 imposed on the dark ones. If they are now examined against a 

 white background, such as a piece of white paper, they still appear 

 bluish, but are much paler in colour owing to their transparency. 

 If they are further observed against backgrounds of difterent 

 colours, red, green, yellow, orange, violet or blue, they always 

 appear distinctly blue, although the background may be seen 

 through them, thus complicating the apparent colour. Against a 

 neutral background or a dark-brown one such as dark-brown paper 

 they appear as blue as when viewed in their natural positions on 

 the wing. Furthermore, when two of these blue scales overlap 

 the density of the blue is very much increased, and in the natural 

 positions they occupy on the wing there is a great deal of such 

 overlapping. Again, it will be noticed that the blue scales taken 

 from the wings of very pale or silvery blue butterflies, such as 

 Lyccena argiolus, or psendargioliis, appear very pale blue when 

 isolated and examined by reflected light, and are practically 

 invisible against a background of white paper. With transmitted 

 light they appear very pale yellow. Similar scales taken from 

 butterflies of a more intense blue, such as Lyccena hellargus, 

 appear darker blue by reflected light, and much darker yellow by 

 transmitted light, which is easily and obviously explainable on 



