218 Lilian J. Gould's experiments 



chosen, which had very dark green leaves and brown 

 woody stems ; and further, with the sprigs of the food- 

 plant were mixed a number of small dark-coloured sticks. 

 It was desirable to have these sticks as dark as possible, 

 and, as natural twigs were not easily procurable dark 

 enough in colour, I used dry stems of furze, taken from 

 places on a neighbouring moor where the gorse had 

 been burned in jjatches ; in these places the stems and 

 twigs alone remained, and of course were perfectly dead- 

 black. When the superficial powdery charcoal had been 

 wiped off with a cloth, the larvfe crawled as readily upon 

 these sticks as upon living twigs, and generally rested 

 upon them in preference to the leaves or stems of the 

 food-plant. The following notes refer to these larvsG in 

 No 5:— 



July 8th. — The second ecdysis took place, and the 

 larvae began to darken in colour perceptibly, varying 

 from the usual dusky hue to shades of brown, and 

 brownish slightly mottled with green ; two were green, 

 but very dark. 



July 16th.— The third ecdysis occurred. The larvsB 

 continued to darken, one having become very dark 

 indeed, so that it was almost the colour of the sticks. 



July 20th. — One larva died ; thus 10 were left. 



July 21th.— The fourth ecdysis occurred. 



July 26th. — I drew the darkest specimen, figured in 

 PL XL, fig. 2. The length of the smallest larva at this 

 time was 16 mm. 



July 29th. — The first larva pupated, spinning a 

 whitey-brown cocoon on the upper surface of a leaf. 



Aug. 3rd. — Two more pupated between the sticks. Un- 

 fortunately I omitted to record the exact shade of colour 

 of these three, but they were certainly all brownish. 



Of the 7 larvae left, S were very dark brown, so nearly 

 approaching to black as to be quite indistinguishable, 

 except by the closest search, from the sticks on wdiich 

 they rested ; two were brown, with a slight tinge of 

 green ; and two were distinctly green, though less bright 

 green than the dullest green larva in No. 9. 



Aug. 9th. — 3 more larvae pupated ; one dark brown 

 one and one green one were left. 



Aug. 13th. — The green larva pupated between leaves. 



Aug. 16th. — The last larva pupated. 



