the colours of certain Lepidapterd. 

 2. Artificial Dark Surroundinqs. 



315 



EXPERIJIENTS VIII. AND IX. 



VIII. 



Cylinder. 

 Heiijht . . . . 

 Interm. diam. 

 Approx. capacity . 



182 mm. 

 83 mm. 

 1000 cc. 



Smooth stripped twigs of Salix 

 rubra and other species of Sali.v 

 were enamelled black, and inter- 

 mixed with and placed round the 

 food-plant. 



July 16. — 10 introduced from the 

 " second stock," having been pre- 

 viously in green surroundings, in 

 darkness by day, and illuminated 

 by a lamp at night. 



July 25. — Length about 24-0 mm. 

 7 brown, 3 green, but the latter not 

 bright. 



Aug. 1. — 10 all brown, although 

 some of them not very dark. 



Aug. 13. — 1 had pupated, and 1 

 was missing. 5 intermediate or 

 lifilitish broioi (they had changed 

 in colour before pupating). 3 dark. 



IX. 



Lamp-shade. 

 Height .... 1(U mm. 

 Approx. capacitij . 1300 cc. 



Kough twigs chiefly of Quercus 

 cerris and ehn were enamelled with 

 black, and intermixed with and 

 placed round the food-plant. 



July 14. — 10 young larvfe intro- 

 duced from "first stock" (green 

 leaves and shoots, which became 

 brown towards the end). 



Aug. 12. — 1 green (pupating), 1 

 intermediate, 1 light cJtocolate-brown, 

 7 dark broivn (5 pupating). 



These results harmonize with those of black-paper 

 covered sticks in the case of R. cratcegata (see p. 324), 

 although probably for a different reason. The artificially 

 darkened surroundings did not seem to produce nearly so 

 strong an effect as those which are natural to the larv^. 

 At the same time, the larvae were subject to different 

 conditions for a considerable part of their earlier life, 

 and these probably produced effects which endured till 

 maturity in several instances, especially in IX. It would 

 be well to repeat these experiments, employing similar 

 environments for the whole larval life, and again to make 

 use of black-paper covered sticks, which were found to 

 exercise a very strong influence on this species in 1889 

 (seep. 331). 



TRANS. ENT. SOC. LOND. 1892. — PART IV. (DEC.) 2 D 



