302 Dr. T. A. Chapman's Contribution to 



became largely exposed on either side, and the forward 

 segments of the abdomen ; during the later part of this 

 evolution, the wings several times at intervals made jerking 

 movements, as if the butterfly thought it could fly. 



The bending back of the butterfly was during this same 

 later stage accompanied, or one might say relieved, by a 

 bending forward of the front of the pupa, made easier by 

 the wide dorsal opening of the thorax. Suddenly the 

 object of the wing jerks became evident, as on one of 

 them the head slipped clear of the pupal headpiece, as a 

 result of the sudden shake, and the legs at once came 

 out and in a couple of seconds the butterfly was clear of 

 the pupa, and in about 7 minutes more the wings were 

 fully expanded. If I have made the eft'ect of the bending 

 process clear, it will be realised that it had only to go a 

 certain length, for the head to slip out of the cup-hke 

 pupal cover ; the jerking process obviously made this occur 

 distinctly earlier but it would have happened without 

 it. The wide dorsal opening of the thorax was very 

 striking in view of the empty pupa case taking so closely 

 the form of the living pupa. 



There is considerable variation in the time taken in 

 expanding the wings, from 7 or 8 to 15 minutes, and also 

 in the method of escaping from the pupa. As the pupa 

 matures the wings assume an ivory opacity with a some- 

 what yellow or sallow tint, and the head, thorax and 

 abdomen become dark, gradually the whole pupa becomes 

 nearly black, but the blue tint of the wings is often visible 

 and the rings of the antenna ; this condition exists for 

 about 24 hours, when air begins to show itself between 

 the insect and the pupa case, first usually about the wing- 

 bases, then spreading down the wings, but usually leaving 

 the hind margins of the wings touching the pupa case 

 after all other areas are practically separate from the case. 

 The presence of air is quite obvious, the dark pupa becomes 

 much paler where air is present and shows the ochreous 

 pupa case separate from the darker underlying insect ; this 

 condition may be some further 24 hours in establishing 

 itself. Then for perhaps as much as two or three hours 

 before emergence, the incisions between the segments 

 become extended. 



The emergence of a specimen was again noted at noon 

 on March G. The pupa showed the case as pale, somewhat 

 separate from the insect beneath, the hairs over the ab- 



