Adjustment of colour hi various ptipx, etc. 391 



About 80 of the napi not in the general Exhibition Case 

 are in a second Exhibition Case under the following circum- 

 srances. I had an old breeding-cage (somewhat resembling 

 those previously described, but a Httle smaller) in two com- 

 partments with a glass roof over both ; one of these was 

 lined with black and had its glass top covered with double 

 black tissue-paper, nearly opaque; tlie other was lined 

 partly with orange paper, and partly with yellow paper or 

 yellow-orange leno.and the glass top was covered with three- 

 fold orange leno, transmitting much orange light. Finding 

 that a number pupated on the glass roof, I succeeded in 

 detaching the plate of glass from the roof and mounting 

 it for exhibition in a second case. It will be seen that on 

 the black side there are 34 pupse all bone-coloured and 

 nearly all much spotted with dark ; on the orange yellow 

 side 46 pupse, all green except 4 which are bone-coloured, 

 though with a yellowish tinge, and nearly all the 46 

 practically unspotted. 



I think this second Exhibition Case, in which the pupae 

 have arranged themselves, affords a very effective demon- 

 stration (if the sensitiveness of this species. 



Tiie following section will contain a detailed statement 

 of results by Prof. Poulton. Here it will be sufficient in 

 reference to the first Exhibition Case to point to the contrast 

 between the 10 on black paper or the 8 on black or 

 dark sticks, all of which are dusky, with much black 

 spotting, and the 19 on yellow or orange paper all of 

 which, with one exception, are green, to the 12 on or 

 near cabbage-leaves, many being attached to the glass 

 bottle, most of which are green, and to the varying colour 

 of those in darkness ; the 8 on Dutch gold, the 7 on 

 planed deal, the 8 on green and the 6 on white paper 

 being nearly all bone-coloured, and most of them spotless 

 or nearly so. These results clearly prove the high 

 susceptibility of the pupa. 



All the four species experimented on by me, in pre- 

 paring to pupate vary in colour according to their 

 surroundings, and I do not see any room to doubt, when 

 the 16 pupae of machaon on black paper or dark sticks are 

 compared with the 4 on green carrot-tops, ^or when the 

 18 pupse of napi on black paper or dark sticks are 

 compared with the 12 which pupated on or near cabbage- 

 leaves, that the adaptation must be in many cases 

 protective. 



