454 Mr. Foiilton' 8 farther experiments upon 



The colours of the 20 larvae of the "first lot" were 

 carefully compared May 17, before being arranged in the 

 experiments on the same day. The 5 largest were about 

 21 •0 mm. long, and were lighter in colour than the 

 remaining 15, wiiich averaged about 18*0 mm. in length. 

 The amount of colour-variability was not great, but 

 distinct. The various shades of colour are mentioned 

 under the experiments. The 25 larvae of the "second 

 lot" were very uniform in size, the average length being 

 18'25 mm. ; the colours of these larvae were also more 

 uniform, but 10 were somewhat darker than the others. 



The larvae were fed on various low-growing plants, 

 such as Achillea, sorrel, buttercup, and plantain, as well 

 as on the more well-known food-plants, rock-rose and 

 burnet sanguisorb. They did not eat much, being nearly 

 full-fed when received, and, indeed, some were probably 

 quite mature. 



The habits of the larvae were such as to expose them 

 very thoroughly to the materials made use of in the 

 experiments. Small pieces of chalk scattered on white 

 paper formed the light environments ; coal and peat on 

 black paper formed the dark. In both cases the larvae 

 generally hid under the chalk or coal by day, especially 

 when the food consisted of green leaves. When, however, 

 the rock-rose was employed alone, many of them hid by 

 day among the crowded brown stems in the inner part of 

 the plant. 



The experiments were of three kinds — Dark Sur- 

 roundings, White Surroundings, and Transference Ex- 

 periments. 



Dark Surroundings. 



{See Table, page 455.) 



Light Surroundings. 



{See Table, page 456.) 



Various Transference Experimexts and others to 



BE COMPARED WITH THEM. 



Fifteen of the lighter larvae (although the difference 

 was not great) of the "second lot" were placed, May 25, 

 in a rectangular glass case (LII. Appendix), with a floor 

 of peat and lumps of coal, standing on black paper (below 

 the glass bottom). They were offered rock-rose alone. 



