6oo 
Color and Pattern and their Uses 
ing as to result in producing much variety of appearance in a single 
series of collected individuals. I have noted in collecting these locusts in 
Colorado and California that this variability of coloration is directly associ¬ 
ated with the color-differences in the soil of the localities in which these locusts 
live; the reddish individuals are taken from spots where the soil is reddish, 
the grayish where it is sand-colored, and the plumbeous and bluish from soil 
formed by decomposing bluish rock. 
On the campus of Stanford University there is a little pond whose shores 
are covered in some places with bits of bluish rock, in other places with bits 
of reddish rock, and in still others with sand. The toad-bug, Galgulus ocula- 
tus, lives abundantly on the banks of this little lake. Specimens collected 
from the blue rocks are bluish in ground-color, those from the red rocks 
are reddish, and those from the sand are sand-colored. But the colors 
of these insects are fixed; they cannot, like the chameleon and certain other 
lizards, or like numerous small fishes and some tree-frogs, change color, 
quickly or slowly, with changes in position, that is, movements from green 
to brown or to other colored environment. Variable protective resemblance 
in insects is, as far as known, a variability directly induced, to be sure, by 
varying environment, but all acquired during the development of the in¬ 
dividual insects, and fixed by the time they reach the adult stage. 
The well-known experiments of Trimen, Muller, and Poulton with the 
pupating larvae of swallow-tailed butterflies, Papilio sp., and Poulton on 
other butterflies with naked chrysalids, show that the chrysalids of numerous 
butterfly kinds take on the color, or a shade approaching it, of the substance 
surrounding the pupating larvae, and show also that the result is due to a 
stimulus of the skin by the enclosing color, and not to a stimulus received 
through the eyes, and carried to the skin by the nerves. Larvae just ready 
to pupate were enclosed in boxes lined with paper of different colors; the 
chrysalids when formed were found to be colored to harmonize with that 
particular color of paper by which they were surrounded while pupating. As 
these chrysalids in Nature hang exposed on bark and in other unsheltered 
places, without protecting cocoon or cover of any kind, the actual protective 
value of this harmonious coloration is obvious. 
The larvae (caterpillars) of various moths, particularly Geometrid and 
Sphingid species, often appear in two color types, one brown and the other 
green. Poulton has shown by experiment and observation with some of 
these species that those larvae reared among green leaves and twigs and 
branches become brown. This variable protective resemblance, like that 
of Trimerotropis, Galgulus, and the Papilio chrysalids, also is fixed after 
being once acquired. 
An interesting example of color harmony which may be classified under 
the head of variable protective resemblance that has come under my obser- 
