452 Mr. G. A. K. Marshall on 



The experiments on the power of adaptation of the 

 pupal colours to their environment are very interesting, 

 and prove that the susceptibility resembles that of the 

 allied British species Vanessa urticcV. They also show 

 that tliere is no essential difference between the colours of 

 the pupa3 of the two phases, but merely an adaptive 

 response to environments which differ in colour at the 

 two seasons, as suggested by Mr. Marshall (Ann. and Mag. 

 Nat. Hist., July 1898, p. 33). It is clear, from the experi- 

 ments, that if withered leaves of the usual winter yellow 

 appeared, owing to exceptional circumstances, in the 

 summer, larvae suspended to them would produce gilded 

 pupce instead of the usual dark summer forms, and, 

 hiutatis mutandis, larvaj would produce dark pupas upon 

 dark leaves in the v/inter. 



The highest form of procryptic defence, viz. the power 

 of each individual to respond adaptivcly to any of its 

 different normal environments, here exists in the helpless 

 pupal stage, although the under-side of the wet phase of 

 the imago can only be interpreted on the supposition 

 that natural selection has developed a conspicuous appear- 

 ance. Our own Vaoiessichv however offer examples of the 

 same kind of association in the different stages of a single 

 life history. Thus the pupte of V. urtvuv and V. io have 

 the same specialized power of concealment, while their 

 gregarious black larvie are excessively conspicuous and the 

 imagines themselves by no means palatable to certain 

 enemies of insects (see p. 442). 



No special significance appears to attach to the varieties 

 of the imagines produced in these experiments. The red 

 bar in the cell of No. 5 is a common variety which indeed 

 appears to be universal in the dry phase of the West 

 African P. odavia, and red scales can be detected in this 

 region in a large proportion of the individuals of P. sesamus. 

 The red spots of No. 5 are not specially developed. The 

 latter were largest in an individual exposed to normal 

 conditions (No. 16), while Nos. 14 and 17, also exposed 

 to normal conditions, were among the specimens with the 

 smallest spots. The bright blue shade of the ground-colour 

 of No. 0, exposed to damp heat, is well known in captured 

 specimens from the most northern part of the range of the 

 species as well as the south. 



The specimens were weighed on an Oertling's balance, 

 each pinned on a small cork foot which weighed "06275 

 grammes on June 29, 1902, and '00025 grammes more on 



