360 Professor E. B. Poulton on colowr-relation 
June 26th. The brownish-green larva in the 5th 
stage was dead. The 2 large ones as last described. 
July 2nd. The greenish intermediate larva had become 
mature and was removed. The distinct green one was 
very large, being 64°6 mm. long. The green 1 ground- -colour 
was somewhat dull, and the brown dorsal line broad but 
not dark. The remaining larva was in the 5th stage and 
intermediate. 
July 12th. The last-mentioned larva was dead. The 
other had pupated. 
CONCLUSION. 
The effect of a dark environment during the 2nd stage 
alone, although slight, is very remarkable. The grey 
which overspread the green forms may be compared to the 
grey patches on the dark form in this and so many of the 
other experiments. 
A2. A. betularia. 
May 29th. The 5 betularia larvee re-transferred to green 
surroundings after they had been in black during the 2nd 
and 8rd stages. 
May 31st. All 5 larvee were advancing in the 4th stage, 
and all dark or distinct brown. 
June 2nd. Two larvee were changing the 4th skin and 
22°0 mm. long; the 3 others advancing in the 4th stage. 
Appearance unchanged, 
June 5th. One larva changing 5th skin and medium 
brown ; 2 half-grown in 5th stage and 1 nearly at end of 
it; 2 dark brown, 1 of the larger pair light brown. The 
5th larva in 4th stage and dark brown. 
June 14th. Four approaching the end of the 6th stage ; 
2 very black and 2 similar, except that the ground-colour 
was overspread with light grey, in one case slightly, in the 
other thoroughly. The latter was nevertheless a darkish 
larva. The 5th larva was changing the 5th skin, and 
green with a brown median dorsal line. 
June 15th. One dark larva had become mature and 
was removed. 
June 20th. One dark larva mature and removed. The 
remaining 3 larve were all in the 6th stage. The grey 
colour of one of the dark larvae was still very distinct. 
The brown dorsal line was pronounced upon the green 
larva, 
