366 Professor E. B. Poalton on colour-relation 



June 2Qth. One had pupated, aud 1 was matui-e 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 larvae and 1 intermediate. 

 At the same time the dark larvas were not quite the 

 characteristic forms produced by black-barked twigs. 



C. A. hetularia. 



May 25th. Ten of the 20 hetularia larvte transferred from 

 green to black for the 3rd stage, and re-transferred to 

 green at the end of it when they were changing the 3rd 

 skin and 140 mm. long. 



May 2dtJi. All in 4th stage and all dark. 

 June 2nd. Four in 5th stage, 5 changing 4th skin, 1 not 

 quite mature in 4th stage. All dark brown. 



Juoie 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. 



Jmie l^th. Six nearly mature in the Cth 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 1 lighter and really intermediate. 



June 15th. Three dark larva; had become mature and 

 were removed. 



June 18th. One dark larva mature and removed. 

 June 20th. Two larvae large in the 6th stage, very dark 

 smoky-black with the paired segmental light grey patches 

 distinct. 



June 2<6th. The 2 larvie above described had become 

 mature and were removed. Of the 3 remaining larva', 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 



