806 
ANNUAL REPORT OF NEW YORK 
MIDGE. PUPA. CHANGE FROM AN EMBRYO TO A PERFECT PUPA. 
traced, apparently in and not under the skin of this vescicle; 
whence it seemed that this skin gradually grew to form these 
sheaths. But in these and other instances this embryo-pupa 
would become altered to its perfect pupa form in the night time, 
whereby all my efforts to find one passing through this change in 
the light of day so that I could closely observe it, were unsuc¬ 
cessful, and I at length became aware I should never see it in the 
act of undergoing this change, unless I could master the insect 
and make it change into a pupa when I wanted it to and not 
when it wanted to. Accordingly, in March last, I opened several 
galls to expose this embryo-pupa lying in its cell. I placed these 
galls by day in a warm room and removed them by night into a 
cold room where their tenants would be so chilled as to remain 
stationary, until they were brought back again-next morning into 
the warm room. I thus at last succeeded in observing what for 
so many years I had been striving to see—one of these embryo- 
pupae passing into its perfect pupa form. 
Without reciting the various minute details which I noted 
down during the two and a half hours this change was progres¬ 
sing, I will endeavor in a more brief and general manner to state 
the leading facts which were observed. The reader by referring 
to Plate III, fig. 1 will see a pupa represented in its perfectly 
developed form, the lines running lengthwise upon the middle of 
the figure being the leg sheaths, which come out from under and 
from between the wing sheaths, and along the inner edge of these 
wing sheaths he will perceive, if his eyesight is good, a beaded 
line, which is the antennae sheaths. In this embryo-pupa I first 
noticed that the wing sheaths were faintly perceptible, the thin 
skin over them appearing to form their exterior surface, with a 
remarkable depression of the breast between them, where no 
depression had previously existed. This anterior part of the 
worm now began to gently writhe and bend, without any inter¬ 
vals of repose; perhaps by this exercise, as I first thought, to 
force the circulating fluids more briskly and copiously into the 
appropriate channels to develop and expand the several sheaths ; 
the surface hereby being raised in slight waves or wrinkles, 
which would again subside. The wing sheaths were now noticed 
to become more obscure and scarcely perceptible; while at the 
anterior end the bases of the antennae sheaths began to appear, be¬ 
coming longer, as it seemed, as the fluids were forced farther in to 
