398 Mr. Toulton^ sfaiilicr experwients upon 



falls. If WG substitute green for gold, and remember 

 that the intermediate forms are not so common and do 

 not require subdivision into 3 classes, the criteria adopted 

 in the two arrangements become almost identical, as will 

 be seen below. 



Qv j'The darkest forms; the underlying gi-een is completely or very 

 \2 ■ nearly [in some (2)s] concealed by the superficial pigment, 

 ^"' ( which is blacker in (1), lighter in (2). 



('Intermediate forms, with a varying amount of pigment, although 



(3) \ never sufficient to conceal the green colour, which is prominent 



( on the pupa. 



.^ ^Distinct green forms, very bright and glittering in (5), somewhat 



' -' duller and with more pigment in (4). The small amount of 



pigment tends to exhibit a reddish tint. 



(5) 



The chief and obvious distinction is between (1) + (2) 

 and (4) + (5). Completely transitional forms occur, 

 especially among the (3)s, but these are not very 

 common, and a large majority of the pupae are classified 

 with the greatest ease, far more so than in the case 

 of V. urticfe. 



A figure of the green and golden form (5) is shown in 

 Phil. Trans., 1887, B, plate 26, fig. 7, and a representa- 

 tion of the cuticle of the wing of the same form in fig. 10 

 (magnified 7 diameters), showing the small amount of 

 superficial pigment, some of w^hich is reddish. In fig. 11 

 there is a similar representation of the pupal wing of a 

 dark form, (1), showing the relative abundance and in- 

 tensity of the cuticular pigment. 



There is little doubt that the green forms of V. io 

 truly represent the golden ones of V. iirticce, the former 

 being also distinctly golden, although this appearance is 

 rendered less prominent because of the green colouring. 

 They are, furthermore, produced in almost every case by 

 the same stimuli. 



In the following account all the experiments which 

 are intended to test the effects of various coloured back- 

 grounds and screens will first be given, with their details. 

 The results will be analysed at the end of the section 

 concerned with this species, after the consideration of 

 various other experiments, dealing w^itli the length and 

 susceptibility of the preparatory stages and the effects 

 of conflicting colours. Thus the arrangement will not 

 necessarily follow the order in which the experiments 

 succeeded each other. 



The effects of various colours will now be shown in 

 the accompanying tables. 



