594 



Color and Pattern and their Uses 



membrane which gradually change in the few or many days of pupal develop- 

 ment into typical scales (Figs. 782 and 783). 



FIG. 780. Scales from a single fore wing of Heliconia sp., showing gradations from scale- 

 hair to specialized scale. (Greatly magnified.) 



We have studied now with some care the general character of the scale- 

 covering of moths and butterflies, and the actual structural make-up and 



the origin of the indi- 

 vidual scales. And we 

 learned at the very begin- 

 ning 

 it is 





FIG. 781. Scales from a single hind wing of the 

 goat-moth, Prionoxystus robince, showing gra- 

 dations from scale-hair to specialized scale. 

 (Greatly magnified.) 



of our study that 

 the scale - covering 

 which is the producer or 

 carrier of all the brilliant 

 and varied color and 

 pattern which character- 

 ize the moths and butter- 

 flies. When we rub off 

 the myriad little scales 

 the wings themselves are 

 found to be colorless, transparent. We have now to note how it is that 

 the scales, the color-carrying organs, actually produce the colors. 



The scales in their fully 

 developed dry condition are 

 chiefly cuticular in structure, 

 but they may contain pig- 

 ment granules and various 

 substances left by the hypo- 

 dermal cell-layer in drying. 

 The colors of the scales are 

 to be classified then as both 

 cuticular and hypodermal in 

 character, and both chemical 

 and physical in origin. For 

 the most part they are strictly 

 combination colors due to 



FIG. 782. Diagrammatic figures showing the devel- 

 opment of the scales on a wing of Euvanessa anti- 

 opa; at left, cross-section of bit of pupal wing show- 

 ing the two wing-membranes and intervening space 

 or wing-cavity; at right, cross-section of a single 

 wing-membrane in older pupal wing, s.c., scale- 

 cells; hyp., hypodermal cells ; /, leucocytes; 5, devel- 

 oping scales. (After Mayer; greatly magnified.) 



