COLOR AND COLORATION 199 
variegated coloration of lichens. Only the younger larve, 
however, proved to be susceptible to the colors of the environ- 
ment; unlike those of Amphidasis betularia, in which the older 
larve also were sensitive to the surrounding light. Here 
again, natural selection is unnecessary, even if not superfluous, 
as an explanation of this kind of protective coloration. 
Effects of Temperature.—The amount of a pigment in the 
wing of a butterfly depends in great measure upon the sur- 
rounding temperature during the pupal stage, when the pig- 
ments are forming. Black or brown spots have been enlarged 
artificially by subjecting chrysalides to cold; hence it is probable 
that the characteristically large black spots on the under side 
of the wings of the spring brood of our Cyaniris pseudargiolus 
are simply a direct effect of cold upon the wintering chrysal- 
ides. Similarly the spring brood (variety marcia) of Phy- 
ciodes tharos owes its distinctive coloration to cold, as Ed- 
wards has proved experimentally. Lepidoptera have been the 
subject of very many temperature experiments, some of which 
will be mentioned presently in the consideration of seasonal 
coloration. 
Speaking generally, warmth (except in melanism) tends to 
induce a brightening and cold a darkening of coloration, the 
darkening being due to an increased amount of black or brown 
pigment. Temperature, whether high or low, seldom if ever 
produces new pigments, but simply alters the amount and dis- 
tribution of pigments that are present already. 
Effects of Moisture.—Very little is known as to the effects 
of moisture upon coloration. The dark colors of insular or 
coastal insects as contrasted with inland forms, and the pre- 
dominance of dull or suffused species in mountainous regions 
of high humidity, have led observers occasionally to ascribe 
melamsm and suffusion to humidity. In these cases, how- 
S, 
ever, the possible influence of low temperature and other fac- 
tors must be taken into consideration. The experiments of 
Merrifield and of Standfuss showed no effect of moisture upon 
lepidopterous pupe. 
