362 Professor E. B. Poulton on colowr-relation 
stage, and of these the smallest was dark brown while the 
other 2 were light greenish-brown. 
June 3rd. The five largest larvae were changing the 4th 
skin, and were placed in a cylinder (B*) with ‘black sticks. 
Their colour was as described on June 2nd, and their 
length 20°5 mm. The colours of the remaining 10 larvae 
had not altered. 
June 5th. Only 9 larvee were found. Two larve were in 
the 5th stage and bright green. Five were more or less 
advanced in the 4th stage, and were distinctly green with 
a variable degree of development of brown patches. Two 
were much smaller in the 4th stage and lhght greenish- 
brown in colour. 
June 20th. Three larve were large in the 6th stage, and 
all very bright green with eae a trace or no trace at all 
of a brow nish tint along the median dorsal line. The other 
6 larvee were not noted on this date. 
June 26th. Only 8 larve were found. Two of the 
largest green larvee had become mature, and were removed 
for pupation. The remaining 6 were of various sizes, but 
all were bright green except one. 
July 2nd. One green larva was mature and was re- 
moved. Three were in the 6th stage,2 bright green, one of 
them with a little brown on the sides and a brown dorsal 
line; the 3rd was intermediate, with a brown dorsal line, 
and green and brown patches alternating on the lateral 
surfaces. One was changing the last skin and one in the 
5th stage, both bright green. 
July 12th. One green larva mature and removed. 
The 2 small ones were dead. Of the two remaining larvee 
in the 6th stage 1 was bright green and 1 intermediate. 
CONCLUSIONS. 
The only point which calls for remark is the occurrence 
of a single intermediate larva. This was a_ probable 
result of the large numbers of the young larvie in a single 
cylinder: so that some effect in a specially susceptible 
individual followed from the presence of other young 
brownish caterpillars. 
B.A. betularia. 
May 20th. The 20 betularia larvee changing the 2nd skin 
transferred from green leaves and shoots to an environment 
