424 Mr. F. MerrifieUl atui Mr. E. P.. Poulton 07i 



1887, /. c, an 1 Trans. Ent. Hoc. Lond. 18y2, /. e.: see also 

 G. C. Griffith's experiments on this species in Trans. 

 Ent. Soc. Lond. 1888, p. 247.) 



It is interesting to observe the rehition between tlie 

 effects of darkness (4) and those of clear glass (14). Tiie 

 latter produced even darker pupai relatively to the former 

 than in the case of 7*. hmssic/v. 



The table does not support Mr. Merrifield's conclusion 

 that the yellow (9, 10, 11) was less efifective than in the 

 case of P. hrassiae. The six pupaj were of the two liglitest 

 degrees, four of them green and the other two greenish. 



The effect of the green and orange screens (7, 13) is 

 confirmatory of previous results with other species (I\ 

 Irasskx. and V. io). 



It is not necessary to comment further upon the other 

 results, all of which will be clear upon an inspection of the 

 table on p. 423. 



//^^—EXPERIMENTS UPON THE PUP^ OF 



Vancssida\ 



1. Experiments upon the Pup/E of Vanessa nrtuw. and 



Pyrameis cardui. (C. B. S. and E. B. P.) 



In the course of our investigations in 1898 into the 

 struggle for existence during tlie pupal period of Vanessa 

 ■urticie it was necessary to produce a very large number 

 of pupsB with colours as widely contrasted as possible. In 

 order to achieve this we made use of black surroundings 

 on the one hand and gilt (Dutch " gold "), yellow, orange, 

 and white on the other. There was abundant evidence in 

 the 700 pupie which we obtained of the previously recorded 

 influence of these surroundings, and also, to our frequent 

 annoyance, of the effect of the dark surfaces of the larvse 

 upon one another. In fact so powerful was this influence 

 and so gregarious were tlie larva) under the conditions of 

 our experiments that intermediate pupaj were generally 

 produced when the lightest forms were desired. The con- 

 ditions of the investigation rendered it impossible to isolate 

 so many larvas in separate cases. 



Many of the larva? pupated on the leaves and stems of 

 the food-plant (nettle), and when isolated brilliant golden 

 pupse were almost invariably produced. 



A few larvse of P, cardui were also found and subjected 

 to black and white surroundings : the pupoe being dark in 

 the one case, and light, and often brilliantly metallic, in 

 the other. 



