rO THEIR SURROUNDINGS 69 



Tliese experiments were made principally with 

 the Small Tortoise-sliell (Aglais urticae) ; others 

 upon the different species of Pierinae were quite 

 similar, the influence of black surroundings being 

 to produce dark chrysalids, and the greater the il- 

 lumination the darker the chrysalids, this last re- 

 sult being the reverse of that obtained with the 

 Vanessini ; white produced light colored chrysalids, 

 and the greater the illumination the lighter the 

 chrysalids ; dark red produced dark, deep orange 

 very light green chrysalids ; pale yellow and yel- 

 lowish green surroundings produced rather darker 

 chrysalids than the orange ; and bluish green 

 much darker, while dark blue produced still darker 

 chrysalids. 



There is thus seen to be a certain difference be- 

 tween different sorts of chrysalids as to the effect 

 of the color of their surroundings, some being de- 

 cidedly affected by colors which have no influence 

 upon others. Probably a careful study of the nat- 

 ural conditions under which pupation takes place 

 may lead to better comprehension of a fact at pres- 

 ent not clearly explainable ; and may bring other 

 instances into harmony, as where, according to 

 Fritz Miiller, a Brazilian Swallow-tail, evander, is 

 said to have both brown and green chrysalids with 

 no intermediate forms, and both produced under 



