The HISTORY of INSECT 8 
A particular treatife on the Culex or Gnat, which likewife belongs to the fic 
method of the third order of natural changes called the Nymph, 
S Ants, Bees, and Beetles are generated 
.. froma vifible egg, in fuch a manner 
that an intermediate Worm firft iffues out.of 
this egg; in the fame manner a Worm or Ver- 
micle, out of which the Gnat has its origin, is 
produced from the egg of a winged parent. 
As the feveral parts of the Worms out of which 
the juft mentioned three infects arife and increafe 
by degrees under the skin, and the creature having 
caft it, at length appear to our fight, all thefe 
incidents have place in the Worm and Nymph of 
the Gnat. But there is, notwithftanding, in this 
infect a confiderable difference, which is, that 
whilft the Nymph of the Ant, Bee or Beetle, 
is without motion, and cannot change its place, 
this Nymph of the Gnat, on the contrary, has 
the power of loco-motion, and fwims in the 
water; for this reafon, it appears at firft fight 
to approach in a great degree to the Nymphs 
of the fecond order. 
On a juft examination of the fubjeét, this 
difficulty will be found, however, of {mall mo- 
ment: for the Nymph of the Gnat, in rea- 
lity, has no more motion in its legs than the 
other Nymphs. of this third order; for it is 
never obferved that it moves in the leaft 
its head, breaft, horns, wings or legs ; the con- 
trary whereof is obferved in Nymphs of the 
fecond order. For this reafon, though the 
‘Nymph of the Gnat has fo ftrong a power of 
moving from place to place, yet that is no ob- 
ftacle to prevent our referring it properly and 
juftly to the third, and not to the fecond order. 
The true reafon of the difference confifts in 
this, the change which the tail of the Nymph 
of the Gnat undergoes, is not fo remarkable, 
as that the Nymph fhould thereby lofe the fa- 
culty of moving briskly. The tail is the only 
part, by the help whereof this Nymph changes 
place. The limbs and other parts in this 
Nymph, are in [reality as immoveable as they 
are in the Nymphs of Ants, Bees and Beetles. 
And even thefe Nymphs are not wholly de- 
prived of the power of moving their tail, as 
is evident in the Nymph of the Rhinoceros- 
Beetle juft defcribed ; for this can, by the mo- 
tion of its tail turn itfelf a little in its terreftrial 
habitation. But in the Nymphs of Ants and 
Bees this is not obferved, until they have paffed 
the greater part of the Nymph ftate, and are 
very near changing their skin. Having there- 
fore removed this difficulty, which might ap- 
pear more confiderable than it is to thofe lef 
acquainted with thefe changes. I thall proceed 
to give the particular hiftory of the Gnat and 
* There is not in all the infect world a creature more ha 
rate microfcope difcoyers to us very clearly what 
what dusky, but as it grows towards the change, it becom 
motion of the itomach and inteftines are perfectly feen, 
very clearly. 
ppily fuited to fhew the feveral operations of life than this. 
pafies within its tran 
and its Nymph; from the particulars of which 
all thofe things which have been faid in the 
preface will be better explained and eafier un= 
derftood. 
The Gnat is produced out of a very {mall 
ege, which is expofed or caft into the water 
by the parent Gnat; when fhe is engaged in 
laying her eggs, and in a few days this pro- 
duces a very fmall Vermicle or Worm*. I 
was firft informed that the Gnats {prung out 
of the water by the curious and learned Mr. 
Duifien, a very vigilant proteftant minifter at 
Saumur in France, who had obferved it in his 
kitchen garden, where there was a ftone bafon 
with water in it, out of which he faw plainly 
that Gnats arofe at a certain feafon. , 
Afterwards, on my return to Holland, I 
found the Worm of the Gnat fwimming in 
water, and immediately took its figure. Hence 
it happened, that when I faw it in the ad- 
mirable figures of Dr. Hook’s micrography, I 
immediately knew it, fince that very learned 
Englith gentleman has delineated it with the 
greateft accuracy. But this celebrated writer 
does not feem to me to have examined the tail 
of that Worm with fufficient attention. I thall 
obferve further, that the Nymph of the Gnat 
has been fomewhat improperly exhibited by 
him, unlefs he had fome other fpecies of this 
infect. This is the more probable to me, as I 
find there are various Nymphs of Gnats, as 
well as many kinds of the Flies themfelves. 
In Tab. XXXI. fig. 1v. I exhibit in its na- 
tural fize the Worm out of which the Gnat 
is produced. The fame is likewife reprefented 
in fig. v. magnified by a microfcope, and thus 
it prefents to the eye very obvioufly the con- 
ftruction of its breaft and body. “It may be 
likewife obferved here, in what manner it raifes 
itfelf to the furface of the water by the help 
of its tail, and alfo the conftru@tion whereby 
it is divided into the head, breaft, body and 
tail. 
In the head, which lies funk under the wa- 
ter, I have fhewn in this figure various particu- 
lars particularly the eyes, the horns, and the 
lower part of the mouth. The eyes are black aa, 
. and have a {mooth and polithed furface; nor are 
they divided like a clufter of grapes, or by an 
hexagonal network, as in many infects,’ but 
are of a figure fomewhat lunated or like a cret- 
cent. The horns are fhaped not unlike the 
collar-bones, Tab. XXXI. fig. v. 54, in the 
human fpecies, and are furnithed with hairs to- 
wards their ends. . The opening of the mouth 
A mode- 
fparent body. ‘The creature is at firft greenifh and fome- 
es pale and greenifh. At that time the beating of the heart, and the 
and the two principal pulmonary tubes may be traced along the 
ir courfe 
R r is 
