390 Mr. F. Merrifield and Mr. E. B. Poulton on 



while the remaining two were much darker still, being of 

 a purplish-brown deepest in tint over the wings. 



These small numbers are not sufficient to prove the 

 susceptibility of this species ; but they render such 

 susceptibility probable. It is to be hoped that larger and 

 more varied experiments will be made by those who have 

 the opportunity of obtaining considerable numbers of the 

 larvae of F. iwdalirius. 



i).— EXPERIMENTS UPON THE PUPiE OF 



Pieris 7iapi. 



1. Experiments upox the Winter Pup.e of Pieris napi. 



(F. M.) 



I exhibited to this Society on November 2nd, 1892 

 (Proceedings 1892, p. xxx), some pupae of P. napi show- 

 ing that the species was susceptible. In this present year 

 I was experimenting on the species for other purposes, and 

 determined to avail myself of the apparatus I had to 

 provide for experiments on the coloration of pupse of P. 

 machaon. Mr. Harwood supplied me in the early part of 

 August with a number of females captured in the vicinity 

 of Colchester, and from them I obtained several hundred 

 eggs on watercress, on which I fed the larvae till about 

 their last stage when that food was largely supplemented 

 and finally replaced by cabbage. These when approach- 

 ing pupation were ex^josed to the same colour influences 

 as the machaon larvas had been (substituting green 

 cabbage-leaves for carrot-tops), and to the following in 

 addition (16) planed deal in shade, (17) planed deal in 

 light. 



They seemed very unwilling to pupate on orange 

 (except on the glass in front of the orange paper), so I 

 shut up some in (18) a threefold yellow-orange leno 

 cylindrical bag with single leno on the top, and orange 

 paper outside two-thirds of the circumference, and here 

 they were obliged to pupate. 



In this species and in P. brassier my results are too 

 numerous for me to show the whole in the Exhibition 

 Case ; but I have brought with me in glass-bottomed 

 boxes, so that they can be seen, all the pups of both 

 species which are not thus displayed (m the Exhibition 

 Case), duly classified. There are in all about 340 pupae of 

 P. napi. 



