tlie colours of certain Lepidoptera. 433 



glittering and darker non-glittering forms are shown in 

 the accompanying plate (Figures 13 and 12, x 2), It 

 is there shown that gilt surroundings, and, to a lesser 

 degree, a clear glnss cylinder roolVd with white muslin, 

 tend to produce light ]")upfe, witli extremely hrilliant 

 metallic spots and ]);itehes, hut without any suffusion of 

 the whole pupal surface with gold, such as happens in 

 the hrightest pupa^ of V. wticce. Black surroundings in 

 darkness, on the other hand, produced dark pupa), with 

 very slight traces of gold. No other experiments were 

 attempted for want of material. The pupa^ of G. cardui 

 have, I holicve, never hitherto heen suhjected to these 

 experiments. 



The following experiments have been conducted upon 

 the larva? during the past year, and one in 1888. The 

 larvae were captured in the field, and, as they are always 

 isolated, it is impossible to obtain the product of a single 

 pair of parents ns in the gregarious J^anrssuhe. 



E.rperiwcnt 1. Black-covered cylinder in, darkiicsfi. — A 

 single pupa of V. atalanta was suspended from the black 

 paper roof. It was dark from the strong development of 

 a network of black pigment over the whole surface : very 

 slight development of gold. 



A single pupa of C. cardui was similarly suspended, 

 and was dark, due to the appearance of spots on the 

 dorsal area and abdominal segments, and of a dark net- 

 work on the wings and limbs. There was not much 

 gold for this brilliant pupa, the dorsal line and lateral 

 stripes glittering but feebly. 



These and the other pupa; were compared Aug. 9. 



Experiment 2. Black-cornered cylinder in strong lif/ht, 

 the black paper heinrf outside the glass (VI.). — One pupa 

 of each species was formed under these conditions. As 

 in the last experiment, both were dark, with a slight 

 development of gold. 



Experiment 3. Ratlter larger cylinder , similarlj/ arranged 

 (F.). — A single darli pupa was suspended from the glass 

 roof. Rather more gold was present than in the last 

 experiments, although but little for the species. 



Experiment 4. Similar cylinder to the last, excejjt that 

 black was replaced by gold (XXVIII.). — Two pupae were 

 formed, one suspended from the glass roof, and one from 

 the food-]dant near the gold background. Both were 

 very light and glittering. A single pupa formed in 



