348 Mr. Voulton's further experiments upon 



The larvte of XIV. were much more crowded than 

 those of XL, but became equally green, or perhaps even 

 brighter. I attribute this to the presence of the golden- 

 green twigs of Salix viminaUs upon which the larvae 

 rested, and which influenced them strongly. We see 

 this when we compare the rates at which the effects 

 were manifested in XI. and XIV. Thus XIV. were far 

 more strongly influenced by July 19 and 26 than XI. by 

 July 21 and 30 respectively. The larvre manifest a 

 strong tendency to rest by day on anything twig-like, 

 greatly preferring it to the leaves. When the latter are 

 offered alone they frequently rest on each other, and 

 hence their progress towards greenness is retarded or 

 even arrested if they are sufficiently crowded. 



The result of the transference of green larvae from 

 XIV. to dark surroundings (XXVI.) for the whole of the 

 last stage, and in one case for most of the last stage but 

 one also, showed that there was no power of further 

 change. No effects at all were produced by the trans- 

 ference. This supports the result of the converse experi- 

 ment already described (see p. 344, Expt. 11. ). And yet 

 the dark surroundings to which these larvae were removed 

 had every opportunity of influencing them, if this were 

 possible ; for the larvae almost invariably rested on the 

 dark twigs with which their colours were in such marked 

 contrast. 



2. Artificial Green Surroundings. 

 [See Tabic, page 349.) 



Omitting XV., the larvae of which may have been 

 affected pathologically by the green pigment, the other 

 experiments show that the larvae are affected in the 

 direction of green, but not nearly so strongly as when 

 the natural green surroundings are employed. The 

 effects of the dark green enamel were very similar to 

 those of the green leaves and shoots when the larvae are 

 crowded (Experiments XII. and XIII.). It is probable 

 that the quality of the green light was less effective than 

 that reflected from leaves and shoots : this will be 

 considered later on (see Conclusions). The lighter 

 green enamel (XVIII.) produced much stronger effects 

 in the direction of green, but not equal to those of 

 natural surroundings when the larvae are uncrovvded 

 (XL and XIV.). It would, however, be well to repeat 

 the experiment over a longer period of larval life. 

 Stronger effects would probably be witnessed, especially 

 under the conditions of XVIII. 



