BY THOMAS P. LUCAS, M.R.C.S.E., ETC. 67 



He likewise found that the opposite conditions obtained 

 where the pupae were submitted to heat. He submitted 42 for 

 6 hours to a temperature of 104deg. F. ; then for 12 hours to a 

 natural temperature of 72deg. F. ; then for 6 hours to a higher 

 temperature of 104deg. F. ; then for 12 hours to a natural 

 temperature of 72deg. F. Twenty-eight butterflies emerged. 

 The red was deepened, spread out in wider area, and scattered 

 in scales over the thinned-out black marks and pattern. In a 

 word, these were thus prepared for a tropical or sub-tropical 

 sunshine existence. 



The surroundings of the pupa often affect the colour. Most 

 chrysalises are chocolate, brown, or black, or tinted with violet. 

 These mostly bury in the ground, beneath a stone, the bark of 

 a tree, &c., or in a cocoon. But some butterflies, and even moth 

 pupae, hang suspended on their food plant or otherwise, and 

 secure more or less the warmth of the sun's rays. Those against 

 rails, dark stems, &c., are generally brown. Those among green 

 herbage are green or light brown, and often gilded with gold. 

 Poulton found that caterpillars turning, with a background of 

 white paper, gilded paper, or iu a strong light, were oftener 

 green or light brown, and were more gilded than those which 

 turned against a background of black or in the dark, which 

 latter were generally dark brown. 



The green chlorophyll in the food of the caterpillar gives 

 colour, and probably pigment foundation for light to play upon. 

 Greens, yellows and browns may be thus accounted for. Gold 

 is stated to have been in sufficient quantity to answer to analysis, 

 and many scales appear like silver. Probably iron yields colour 

 in its high dilutions. But it is almost safe to argue that in the 

 same manner in which the elements give colouration to the 

 plant and flower in their organic appropriation, so these same 

 elements in the plant, eaten by the caterpillar, are laid up to 

 give colouration, if needed, to the larva, and, when further 

 needed, to the imago. 



Many caterpillars are dimorphous ; others are polymor- 

 phous. This is caused by the distribution of the green colour- 

 ation and brown pigment. Many noctuid moth caterpillars, 

 which feed at night, are brown ; others, which hide in herbaceous 

 leaves, are green. The hawk moth caterpillars are often 



