72 The BOOK 
They pretend to fee things, which never exifted, 
and they well deferve to be compared to thofe 
perfons, who, fometimes, with equal truth, think 
they difcover armies in the clouds, which were 
never formed but in their own difturbed imagi- 
nations, } 
For my part, I call this change, by the name 
of the Vermiform-Nymph ; becaufe, in this ftate, 
the creature externally refembles a Worm, and is 
at the fame time really a true Nymph, and not a 
Chryfalis, under the former Worm’s fkin, which 
it {till retains together with the internal figure of 
a Worm. And accordingly, the limbs of a latent 
Nymph, appear, in fome meafure through, toa 
careful examiner, this fkin. But I have already 
fafficiently explained this fourth order of muta- 
tions in its proper place. 
The Nymph, thus concealed under the fkin 
of the Mite, is of a moft elegant form. But to 
have a diftine view of it, ’tis neceflary to break 
this {kin, and then ftrip it off from the Nymph. 
This muft be done with great dexterity and cir- 
cumfpeétion. By this means, we at laft obtain 
a fight, and a beautiful one it is, of the head, 
thorax, and abdomen of the future Fly, as | 
have reprefented them of their natural fize, 
Tab. XLIIL. Fig. x11. But to perceive them di- 
ftinGly, we muft ufe a microfcope; with the 
affiftance of that ufefnl inftrument, we difcern its 
two little horns, Fig. xi11.@, growing out of the 
forepart of its head, and under them its two eyes, 
of Ni AY) UR E 2408, 
66, which take up the greateft part of the head, 
Under the eyes lies the probofcis or trunk, ¢ 
with all its parts. Near the probofcis appear the 
firft pair of legs, dd, and under the firft pair the 
fecond, ee, difpofed in a very beautiful order, 
The rings neatly folded up, ff, prefent them- 
{elves next, and under them, we may fee in 
what manner the hinder pair of legs, gg, lie 
ftretched againft the abdominal rings of the body, 
h: thefe, with the extremity of the anus, are 
very diftin@ly to be feen. In fine, all thefe 
parts are arranged together, with fo much art 
and beauty, that it is impoflible to give a juft 
defcription of them. They will be feen yet a 
great deal more diftinétly, by divefting the 
Nymph of the {kin that immediately enclofes it, 
At firft all thefe parts are of the colour of co- 
agulated milk, but as fluid as water, which makes 
it very difficult to feparate them ; nor can they, 
after all, be accurately diftinguifhed one from an- 
other, becaufe they are at this period, all of the 
fame colour, In ten or twelve days, they ac- 
quire fo much confiftency, and fo much of their 
peculiar colouring, as to affume the form of a 
complete Fly, on throwing off the internal mem- 
branes that cover them, within the former 
Worm’s fkin, which they ftill retain for twelve 
days longer; when the new infect, having ac. 
quired {ufficient {trength to appear abroad, breaks 
this external enclofure likewife, and launches 
into the air, in the following manner, 
The manner in which the Nymph of the Mite breaks from its membranes, and af- 
fumes the form of a Fly, : 
a HE firft thing obfervab!e in this change is, 
that the Vermiform-Nymph lofes its deep 
red colour, and grows much darker; then the 
Nymph itfelf breaks that part of the fkin, which 
covers its head intotwo parts, Tab. XLUI. Fig. 
xvi. @, 6, and at the fame time throws off from 
every part of its body a very flight membrane, 
which it leaves within the old fkin. When this 
is done, there breaks out from under this fkin, a 
little infect like a gray Fly, without wings, but 
fo nimble, that it runs immediately about as if 
it were feveral weeks old. 
Sometimes after this, the new born Fly rubs 
with its forefeet, that part of its head which lies 
immediately over its horns; for, on this fpot, 
there arifes a confiderable fwelling, with a vio- 
lent pulfation in it, The Fly never gives over 
rubbing, till it has difperfed the fwelling, and 
made it entirely difappear. °Tis probable, that 
it was in this part, the fore-legs lay while the in- 
fe& remained in the Nymph-ftate. The next 
thing the Fly does, is to rub very gently with 
its hinder-legs, the furface of its two fhort little 
wings, which are as yet folded up, till it tho- 
roughly expands, and difplays them. ‘This ope- 
ration may be very diftinétly feen, and I have 
reprefented the great folds, Tab. XLII. Fig. 
xiit, ff, which the infect thus expands. ‘The 
Fly, after this labour, takes a little reft, remain- 
ing quiet until the wings fully difplay themfelves, 
yy r 
\ 
which is performed very fuddenly, for their ve- 
ficles are no other than ramifications of the wind- 
pipe, which run up and down through them; 
{o that we may eafily conceive how they may be 
fo fuddenly expanded by an inje€tion of blood 
and air from the main trunk, ‘The infe@t, how- 
ever, cannot as yet fly; its wings yield fome 
blood if they be wounded at this time; whereas, 
when they are once perfe€tly dried, which. is 
done in a quarter of an hour, it is impoffible to 
obtain the leaft drop of blood from them, even 
by cutting them off, the veflels being in that 
time perfectly dried up and clofed; for my part, 
I firmly believe that all the membranes of ani- 
mal bodies are no other than a kind of webs, 
confifting of veflels confolidated in this manner, 
as may be {een in the blood-veflels of the epider- 
mis, which d:y up as foon as the foetus comes 
from the womb, and ceafes to draw nourifhment 
from that part of its covering. ; 
The Fly produced from the Mite is one of 
the common kind; and it affords very few things 
worth our notice: this may be feen by the two 
figures, in which I have reprefented it of its na- 
tural fize, Fig. x1v. The wings, when they lie 
on the body, extend beyond the extremity of it. 
I give alfo a figure of the male, after a drawing 
taken with the microfcope, in which the head, 
thorax, and abdomen are feen very diftin@ly. On 
the forepart of the head, there arife two fhort 
. horns, 
