82 
INTRODUCTION. 
pupie obtected. In this state, they are of course in- 
capable of moving from the place to which they are 
fixed, and indeed of making a movement of any kind, 
save twisting the abdomen to one side, which they 
generally do -when disturbed. Scarcely any other 
symptom of animation is perceptible, but during the 
continuance of this apparent torpor some important 
changes ara taking place internally. The milky fluid 
which at first filled nearly the whole of the interior, 
is gradually absorbed and assimilated by the growing 
embryo, while the watery portions pass off by eva- 
poration. In this way the germ of the future fly is 
enlarged and matured, till it ultimately fill the whole 
cavity of the puparium or pupa-case. The process 
of respiration is likewise carried on, though to all 
appearance in a very languid manner, through the 
medium of a series of spiracles or air-holes placed 
on the sides of the abdominal segments. 
The greater number of butterfly chrysalides are 
of an angular figure, wide and obtuse at the head, 
and tapering to the tail in the form of a cone. 
Besides having various angular projections on diffe- 
rent parts of the surface, the head terminates in a 
conical projection, which is very frequently double. 
In a pretty extensive group, however, (comprising 
the genera Thecla, Lycmna, &c.) the chrysalides are 
without any protuberance, and of a conical shape, 
the anterior extremity being simply rounded. The 
prevailing colour is brown, often inclining to black ; 
but, in some instances, they are adorned with very 
