366 Professor E. B. Poulton on colowr-relation 
June 26th. One had pupated, and 1 was mature and 
removed. The 3rd larva was greyish smoky-black. 
July 2nd. The last larva had become mature and was 
removed. 
CONCLUSIONS. 
The great power of a black environment is well shown, 
in the production of 2 dark larvee and 1 intermediate. 
At the same time the dark larvee were not quite the 
characteristic forms produced by black-barked twigs. 
C. A. betularia. 
May 25th. Ten of the 20 betwlaria larvee transferred from 
green to black for the 8rd stage, and re-transferred to 
green at the end of it when they were changing the 3rd 
skin and 14:0 mm. long. 
May 29th. All in 4th stage and all dark. 
June 2nd. Four in Sth stage, 5 changing 4th skin, 1 not 
quite mature in 4th stage. All dark brown. 
June 5th, Four changing 5th skin and 33:0 mm. long ; 
2 nearly mature in 5th stage; all lightish brown over- 
spread with a greyish cloud. Three small in the 5th stage, 
2 of them as above and 1 dark brown. One in 4th stage 
and very black. 
June 14th. Six nearly mature in the 6th stage and all 
very dark smoky-black with a pair of distinct grey patches 
on the dorsal surface of each segment. Three in the 5th 
stage, 2 as above and | lighter and really intermediate. 
June 15th. Three dark larvee had become mature and 
were removed. 
June 18th. One dark larva mature and removed. 
June 20th. Two larvee large in the 6th stage, very dark 
smoky-black with the paired segmental light grey patches 
distinct. 
June 26th. The 2 larvee above described had become 
mature and were removed. Of the 3 remaining larvee, 2 
were large in the 6th stage, one bright green with brown 
dorsal line and a small brown patch on anterior part of 
each side of the segments, the other smaller and darker 
with more brown upon it, but still with a bright green 
ground-colour. ‘The third larva in the 5th stage and 
chocolate-brown. 
July 2nd. All 3 in 6th stage, but the smallest was now 
intermediate. In view of the considerable development of 
