1034 General Notes. 
Previous to these writings, observers had freely stated that it was 
the habit of chrysalides to assume the precise coloration of the sur- 
face to which they were attached, and the untested facts of the case 
had been considerably exaggerated. In explanation of the phe- 
nomena in question, the earlier writers held that these correspond- 
ences of color were analogous to those of the Chameleon, or that 
they were photographic. Attention was called to the transparent 
surface of the freshly formed pupa, which might be sensitive to 
ight. Professor Meldola, however, had modified such statements 
by declaring! that “the action of light upon the sensitive skin of 
a pupa had no analogy with its action on any known photographic 
chemieal. No known substance retained permanently the color 
reflected on it by adjacent objects.” 4 
This represents the state of our knowledge at the time of the publi- 
cation of Mr. Poulton’s memoir. In this paper the results of many 
experiments are tabulated, Some of them are very striking. Thus, 
in the case of pupæ of Vanessa, exposed to gilded surroundings, 
many of them appeared as if they had been covered with gol . 
This memoir isa difficult one to abstract, owing to the great amount 
of details. The following appear to be the more important conclu- 
sions :— 
1. There is a great difference with regards to the sensitiveness 
of different species. Thus he proves that the pups of the following 
named butterflies possess an adjustable color-relation to their sur- 
roundings: Vanessa io, V. urtice, V. atalanta, Pieris brassice, 
and P. rape, while, on the other hand, dimorphic pupe, which are 
closely allied to the sensitive forms, may be uninfluenced by r 
rounding colors, e.g.: Papilio machaon and P. polydamus. +8 
the genus Ephyra (Heterocera) the dimorphic pupæ are quite pe f 
influenced by their surroundings, the pupal colors corresponding 
to those of the dimorphic larvæ. : 
2. The previously accepted theory, which explained the pune! 
color-relation as following from the action of light upon the mols 
skin of the freshly-formed pupa, is entirely disproved, and "A 
shown that the influence works upon the Jarva during the peri 
which intervenes between the cessation of feeding and pupation. 
_ This intervening period was carefully investigated in V. rag 
and it was found that, after ceasing to feed, the larve wander 
a variable time, then rest for about fifteen hours upon the su cP 
selected for pupation, and finally hang suspended, head PEE 
for about eighteen hours, after which time pupation takes pice 
By transferring the larve from one color to another, in 
that the color influence works for about twenty hours pr g 
the last twelve hours of the whole period. 
| Proc. Entom. Soc., London, 1874, p. XXIV. 
