152 
Psyche 
[December 
and the brown parent had hatched, twenty-four young from 
each female were selected and divided into two lots of twelve 
each. One lot was then placed in a green cage, the other in a red 
cage. 
The insects at this stage were uniformly of a dull green color. 
They were fed each night with shoots of Tradescantm fluminensis, 
the remains of which were removed each morning to avoid obs- 
curing the background. 
No change could be observed after either the first or the 
second moult. After the third moult, however, those in the 
green cages had taken on a clearer, lighter shade of green, while 
those in the red cages had become perceptibly darker. After 
the fourth moult the difference was striking, — those in the green 
cages remained a clear green, while those in the red cages were 
dark brown. There was but little difference in the rate of change 
between the progenies of the two females. Those from the green 
parent showed, if anything, a more rapid change to brown than 
did those from the brown parent. 
To determine whether the change to dark brown could be 
effected in the later stages of the life history, two individuals 
were transferred from each of the green cages and placed with 
their sisters in a red cage After passing through several moults, 
they became almost dark as those which had occupied the red 
cages from the beginning of the experiment 
At the same time two brown individuals were removed from 
each of the red cages and were placed with their sisters in the 
green cages to determine whether the color change to brown is 
reversible. In each case the middle pairs of legs of the transferred 
individuals were removed to distinguish them from the others. 
After several moults they had taken on a somewhat lighter 
shade, and when mature they were of an indefinite greyish color; 
but the dark pigment was never completely resorbed. The 
middle legs, however, which were regenerated under the in- 
fluence of the green background were of a peculiar bluish-green 
shade, their color presenting a striking contrast to that of the 
rest of the body. 
In each of these cases no differences could be observed in 
the reactivity of the two progenies. 
