Color and Pattern and their Uses 
593 
hair becomes a scale by shortening and broadening, keeping its free 
tip entire; in others the hair splits distally and then each branch splits 
Fig. 778.—Scales taken from a single fore wing of Megalopyge crispata, showing grada¬ 
tions from true hair to specialized scale. (Greatly magnified.) 
again, and so on, while the base is continually shortening and broadening 
so that the scale form finally reached is a fingered or deeply-toothed 
Fig. 779.—Scales from a single fore wing of Gloveria arizonesis, showing gradations from 
scale-hair to specialized hair. (Greatly magnified.) 
one. But in all the series the final result is that from a long, slender, sub- 
cylindrical hair is evolved a short, broad, flattened, little scale. A study 
of the actual development of an individual scale on the forming wing of a 
butterfly during the pupal or chrysalid stage confirms the hypothesis of the 
evolution of the scales. In the growing developing wing the scales begin 
as hairs, arising by the extension of certain hypodermal cells in the wing- 
