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 of our study that 
it is 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- 
Fig. 781.—Scales from a single hind wing of the m wp ruh nff 
goat-moth, Prionoxystus robinoe , showing gra- nies * Wnen we ruD Ott 
dations from scale-hair to specialized scale, the myriad little scales 
(Greatly magnified.) 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 
- s v. 
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.) 
