Adjustment of colour in various lywpo^, etc. 409 



468), and ascribed to the greater concentration of the 

 effective rays. The stimulus produced a strong effect at a 

 distance (10). The powerful effect of a natural green 

 environment (11) is of great interest. 



The experiment with %vhite, (12 — 17) was especially 

 useful, as this environment had been almost omitted from 

 the previous investigation of this species. It is at once seen 

 that the effect is to produce intermediate pupge, inclining 

 towards the dark side. In this, the results differ widely 

 from those obtained with Vanessa tirtiae and F. io in 

 which white surroundings produced strong effects in the 

 direction of the golden and green pupae respectively. There 

 is great uniformity in the results obtained by the different 

 white backgrounds, and the action at some distance (17) 

 was clear. It will be found that my own experiments (43 

 to 48) in 1898 (see pages 415, 416) lead to the same 

 conclusions as those which result from Mr. Merrifield's. 



Yellow surroundings (18 to 22) produced the usual 

 strong effects in the direction of the palest, greenest pupae, 

 the influence being much reduced in shade (19), and also 

 reduced when acting through glass (20). An influence at 

 some distance was probably exerted in (22). 



Orange surroundings (23 to 27), for the most part, pro- 

 duced the same effect as the yellow, the orange leno (23) 

 being an exception. Influence was strong through glass 

 (25), and at some distance (27). The orange screen (26) 

 produced considerable effects, in accordance with the 

 principles already explained (Trans. Ent. Soc. Lond. 

 1892, /. c.) ; although an even stronger result might have 

 been expected. 



This accormt of the results should be read in relation 

 to the Appendix, in which the colours reflected from the 

 various backgrounds are analyzed. 



3. Experiments upon the Winter Pup^ of Pieris 

 Irassicie. (E. B. P.) 



I also took advantage of the immense abundance of this 

 species to repeat some of the experiments made in previous 

 years upon insufficient numbers. The larvae in part came 

 from St. Helens, Isle of Wight (experiments 5, 6, 37, 38, 

 39, 40), partly from St. Helens and near Reading (13, 41, 

 42), and partly from St. Helens and near Oxford (remain- 

 ing experiments, including those with conflicting colours, 



