^6 Mr. Edward B. Poulton on Gilded Chrysalides. [Feb. 11, 



green ones upon brown twigs, &c. It is probable that less healthy 

 and smaller larvae often produce the brown form, just as diseased 

 Vanessa larvae produce gihled pup^. 



V. Experiments upon Pieris hrassicse and P. rapse. 



1. Effects of Colours — Blach produced dark pupae, and the greater 

 the illumination the darker the pupae (P. rapse), this result being the 

 reverse of that obtained with V. urticse ; ivJiite jjroduced light i3up8e, 

 and the greater the illumination the lighter the pup^ (P. Q-apse) ; dark 

 red (P. hrassicse) produced dark pupae ; deep orange, in both species, 

 produced very light pupae of a green colour ; pale yellow ^ndi yellowish- 

 green produced rather darker pupae than the orange ; hluish-green pro- 

 duced much darker pupae, while darh blue produced still darker pupae 

 (P. rapse only). Hence there is a remarkable and sudden fall, 

 followed by a slow and gradual rise in the amount of pigment formed 

 as the light from various parts of the spectrum from red to blue pre- 

 dominates in the reflected rays which fall on the larval surface. 

 But their effects on the formation of superficially placed dark i>igment 

 are accompanied by changes affecting the formation of greens and 

 yellows, &c., in the deeper subcuticular tissues. Hence the results 

 of any given stimulus are exceedingly complicated. 



2. Oilier Experiments.— It was shown by the method described 

 above that the ocelli are not sensitive in this species, and by similar 

 transference experiments it was proved that the influence acts on the 

 larva and not on the pupa itself. 



YI. Experiments upon Ephyra pendularia. — In this genus of moths 

 the exposed pupae are often green and brown in different individuals, 

 but these colours follow the corresponding tints of the larvae, and 

 therefore cannot be influenced unless the latter themselves were 

 changed, and such susceptibility in the larval state has not been 

 proved for this genus. This is the only known instance of a constant 

 relation between the larval and pupal colours. 



VII. Experiments upon the Cocoon of Saturnia carpini. — It was 

 found that the larvae spin dark cocoons in black surroundings, but 

 white ones in lighter surroundings. 



[E. B. P.] 



