388 Mr. F. Merrifield and Mr. E. B. Poulton 07i 



Above these 5 pupae, on the wooden roof, were 8 pupse, 

 two close together and one near them in the corner. All 

 were light grey (2 a). 



At the opposite end of the cage 3 pupse were scattered 

 over the zinc, one being intermediate between dark and 

 light grey (2 a, b), two, dark grey (2 h). 



On the wooden roof over them was a compact group of 

 5 pupse, all intermediate between dark and light grey 

 (2 a, b) ; while a single pupa loose on the floor was also 

 intermediate (2 a, b). 



Thus there was not a single exception among the pupse 

 on the zinc and wood. Furthermore those fixed to the 

 latter were on the whole lighter than those fixed to the 

 darker zinc. The singular completeness of the result is 

 best shown in a tabular form as follows : — 



33 



It is unnecessary to examine these data further. It is 

 obvious on an inspection of the above table that there 

 is only a single exception to the complete susceptibility 

 of the pupae. 



The much greater susceptibility of this set of pupse as 

 compared with Mr. Merrifield's considered as a whole, and 

 with the few upon which I experimented in 1886 (Phil. 

 Trans. 1887, /. c p. 406), is probably due to their more 

 healthy and vigorous condition, and perhaps in part to 

 some of the results having been obtained under normal 

 conditions (if it is admitted that most of the green pupse 

 were formed in the open). The larvse are not gregarious, 

 so there is no justification for assuming a family tendency 

 towards susceptibility on the part of the set as a whole. 



