Miss E. Bridges upon lepidopterous larvae and pupae. 137 
that the larvae are only influenced by the colour of the 
twigs on which they rest, or of those quite close to them, 
and in the experiments here recorded, all were kept alike 
in clear glass cases with white roof and floor, the only 
difference being in the colour of the few sticks placed 
among the leaves of the food-plant. 
The eggs, about 130 in number, were all laid by the 
same moth, and hatched between August 14 and 16, 1909. 
They were introduced into the different environments 
within a few hours of hatching. The environments were 
as follows :— 
A. Slips of white wood painted crimson with water- 
colour. 
B. Black twigs of birch. 
C. Slips of white wood. (The wood not a dead white, 
but the cream colour of common deal.) 
D. White wood painted a pale green with water- 
colour. 
E. Dead sticks of oak covered with grey- lichen and 
green powdery alga. 
The food-plant employed was elder (Sambucus nigra). 
The larvae proved to have only various shades of black, 
brown and cream at their command. On the pale green 
sticks (D), they became cream-coloured, on the red (A), a 
reddish-brown ; on the lichen-covered sticks (E) no lichen- 
like markings appeared as in the experiment on bidentata 
(see p. 144), but the larvae became a rich black of the 
same colour as the bark, and were most inconspicuous. 
Their sensitiveness showed itself rather in the swiftness 
and completeness with which they adapted themselves to 
the black and white environments (B and C), On the 
first day (August 21) that any were noticed on the black 
sticks, four became black on the back (they were distinctly: 
darker than any of the other sets), and three days after 
this all but two were completely adapted, 7.e. were indis- 
tinguishable in colour from the sticks. Those on the 
white sticks took some time to get rid of all traces of 
their dark markings: the first signs of the “bleached ” 
appearance were not noticed until 12 days after they. 
began to use the sticks (September 2): all but one were 
adapted in 2] days (on September 11). Notes were taken 
every three days with the exception of the first week. 
Those between September 29 and Qctober 11 are omitted 
ag n9 change was then recorded. 
