the colours of certain Lepidoptera. 43? 



5. EXPEEIMENTS IN 1888 UPON THE PUP^ OF ArGYNNIS 



PAPHIA. 



Twelve nearly mature larvfe purchased in the spring of 

 1888 formed tlie material of these experiments. When 

 they ceased feeding, the larvae, divided into two equal 

 lots, were placed in two cases, the one with a white- 

 paper roof, the other with a roof of clear glass, upon 

 which was placed a sheet of black paper. 



Black surroundings (seen through glass). — 6 pupae 

 were obtained and compared June 22. They were all 

 dark varieties, with a considerable development of cuti- 

 cular pigment. The golden spots were as distinct as in 

 the others. 



White surroundings. — The 5 pupae obtained were far 

 lighter, being a light brown with a very slight develop- 

 ment of pigment, except in one which was about the 

 same as the lightest of the other lot. There is ap- 

 parently no tendency towards the suffusion of gilt as in 

 V. urticcE, but the 5 pairs of spots, on pro-, meso- and 

 metathorax, and abdominals 1 and 2, are very distinct and 

 bright, although those on the mesothorax are very 

 small. 



The pupa is evidently highly sensitive, and the effect 

 upon the pigment is certainly such as to promote con- 

 cealment. 



It is interesting to find a case in which the pigment 

 only is affected by the surroundings, and the ghttering 

 spots are equally present in dark and light forms. In 

 this respect the species is at present unique, but no 

 doubt further experiment will reveal the presence of 

 others. In all the Vanessidce the glittering spots are 

 affected by the formation of dark pigment, and tend to 

 disappear in many of the dark varieties. 



6. Experiments in 1888 upon the pupiE of Pieris 



BRASSIC^ AND P. RAP^. 



Before describing the experiments, it is necessary to 

 give some account of the different colour varieties formed 

 in these two species. In P. brassicce we meet with the 

 following classes : — 



" (1). The normal form. In these pupae the ground- 

 colour is always more or less greyish from the abundance 

 and relative size of minute black pigment spots which 



