358 Professor E. B. Poulton on colour-relation 



the 5th still small in the 8rd stage. The black twigs were 

 removed at this date, and the 5 larvae by this means 

 re-transferred to green surroundings. 



June 2nd. Four in 4th stage, and 1 nearly at the end 

 of 3rd stage. Four distinct medium brown colour ; 1 very 

 black. 



June otli. One changing 4th skin and light reddish- 

 brown ; 2 in 4th stage, both darkish brown ; 1 at beginning 

 of 5th stage and medium brown ; the 5th small one was 

 only 9"0 mm. long. 



June IMh. One small in 6th stage, and dark brown 

 with distinct grey markings prominent on it ; 1 changing 

 otli skin and light brown with ventral surface rather 

 greenish ; 2 at end of 5th stage, 1 intermediate and 1 

 similar to but rather darker than the larva changing its 

 skin. 



Jane 20th. Four in 6th stage, 2 dark, overspread with 

 greyish, 1 green with brown dorsal line and lateral 

 patches, 1 dark form becoming greenish on the sides. 



June 2Qth. One dark larva mature and removed. 



July 2nd. The green larva and the one with greenish 

 sides mature and removed. The remaining larva was very 

 dark, with distinct sharpl}'- marked pale yellowish spots on 

 its sides, and one on each side of the dorsal surface of each 

 segment. 



Jul]/ 12th. The larva described above had been 

 accidentally drowned. 



CONCLUSIONS. 



The effect of the dark surroundings is evident. The 

 green environment of the three last stages was doubtless 

 the cause of the greyish tint, the greenish sides, and the 

 yellowish spots on the 3 dark larvae. In the case of the 

 4th larva the effects of the latter surroundings were pre- 

 dominant, although the larva still retained strong traces of 

 its earlier environment in the brown markings. Comparing 

 this result with that of A\ the relative unimportance of 

 environment in stage II becomes clear. 



A^. A. hetularia. 



May 20th. The 10 hetularia larvae re-transferred from 

 black into green at the end of the 2nd stag^e, chancrincr the 

 2nd skin, and 8'3 mm, long. 



