STATE AGRICULTURAL SOCIETY. 
807 
MIDGE. PUPA. TIIE METAMORPHOSIS DESCRIBED. 
fill and expand them; the fore part of the wing sheaths also were 
next noticed to become more plump and distinct than they had pre¬ 
viously been. And now, another phenomenon served to show me 
the real nature of the change which was occurring, but for which 
I should probably have failed of detecting what was actually 
passing directly under my eye. The space between the black Y 
mark of the jaws and the anterior end had been observed to 
gradually expand and become more considerable, till at length, 
this black-mark had moved down to be in a line with the ends of 
the wing sheaths. It was evident these jaws could only be 
moved as they had been in but one manner. A membrane or 
film so exceedingly thin, delicate and transparent that I had 
wholly failed to perceive it, had been gradually crowded back¬ 
ward, these jaws being attached to it and carried along with it, 
till the anterior part of the body was now wholly released from 
it. On carefully looking I could now perceive the wrinkled folds 
of this membrane beyond the ends of the wing sheaths, produ¬ 
cing a very slight constriction of the body at that point. It was 
moved no further, but on becoming dry was in the course of the 
day broken into shreds and flakes which the motions of the pupa 
caused to separate and drop off; whilst over all the remaining 
front part of the body an extremely fine scurf was discerned to 
separate and scale off, like dandruff, but on the back I was unable 
tp detect any exfoliation whatever. 
Thus, from these observations we obtain a pretty full and dis¬ 
tinct view of the processes whereby the insects of this genus 
Cecidomyia become changed from larvae to pupae, by this trans¬ 
formation losing the mouth and jaws of the worm and acquiring 
the rudimentary wings and legs of the fly. As the first step of 
this change, at the anterior end of the larva the cutis or opake 
inner skin becomes wholly broken up and dissolved into a watery 
fluid, whereby the thin transparent outer skin or cuticle is ele¬ 
vated like a vescicle or blister, which occupies about a fourth of 
the length of the worm on its under side but is much shorter on 
its back. • The insect is now in its embryo-pupa state, having 
lost its larva form and having not yet assumed its pupa form. 
In the fluid contained in this vescicle the wings, legs and antennae 
of the future fly now begin to bo developed, whereby the sheaths 
of the wings at length come to be discerned immediately under 
the skin. This skin is exceedingly thin, delicate and transparent, 
