36 
the form of eggs, or whether they proceed from 
them as from an internal principle? A great deal 
may be faid in favour of either fyftem; it is 
therefore neceffary, that I fhould defer, for fome 
time, the difcuffion of this important queftion, 
as 1 cannot yet produce any ocular demonftration 
to {upport either opinions. Neverthelefs, I muft 
obferve to fuch as are fond of natural hiftory, 
that it is impoffible for them to gain a competent 
Knowledge of the difpofitions and changes of 
Caterpillars, without feeding on purpofe a great 
number of thofe infe€ts of the fame fpecies, in 
order to have an opportunity of tracing them 
through all their changes: nor will this care alone 
be fufficient, for nothing but repeated diflections 
ean give any fatisfactory idea of their internal 
parts. The naturalift, who fhould think of fuc- 
ceeding in any other manner, would lofe his 
pains, and remain in perpetual ignorance. 
Ninthly, I reckon, among the creatures of 
my fourth order, thofe Vermi-form Nymphs, or, 
as they are otherwife called Eggs of Worms, 
which are produced by thofe contracted Worms, 
which, it is pretended, iffue from the putrified 
bodies of Aurelie. We fee great numbers of 
different kinds of Flies, iffuing from fuch Worms, 
in a few daysafter they become mationlefs, within 
their fkins, and thereby aflume the appearance of 
thefe Vermi-form nymphs we have been diffect- 
ing. Mouffet was the firft who took notice of 
thefe kinds of mutation. After him Goadaert 
treated of them; and fince himy Redi, and many 
other authors. I have given by itfelf, Tab. 
XXXVIII. Fig. x. a drawing of one of thefe 
Worms, and likewife of one of the Vermi-form 
Nymphs, whofe refemblance to an egg is merely 
fuperficial. 
I place alfo in this my fourth order, the Ver- 
miform Nymphs proceeding from Worms, 
which, contracting themfelves within the bodies 
of Aurelie, without cafting their external fkin, 
thus acquire the fhape of an egg; this is a thing 
which I very feldom have had an opportunity of 
fecing; for thefe Worms generally open them- 
felves a paflage out of the Aurelia, as foon as they 
have acquired their full growth, as I have fhewn 
already. There is fufficient reafon why they 
fhould do this. The Chryfallides are generally 
fomewhat moift, which makes it neceflary for 
the Worms contained in them, to leave their 
bodies, and find out a more convenient fituation 
for their external fkin to harden, in order to their 
becoming Nymphs. But whenever it happens, 
that when all the moifture of the Chryfalis is 
exhaufted by thefe Worms as their food, fo as 
to permit the fkin of the Chryfalisitfelf to harden 
and grow dry, then the enclofed Worms remain 
within it till they become Nymphs, and from 
Nymphs, Flies, to appear abroad ; in which form 
they muft alfo make their way through three 
different fkins, as well as the Flies generated in 
the bodies of Caterpillars, whofe labours on the 
like occafion, have already been taken notice of, 
All thofe Nymphs of our fourth order, hi- 
therto taken notice of, change in the end to diffe- 
rent kinds of Flies, as has been already obferved, 
and I preferve a great variety of the Flies pro- 
The BOOK of NATURE: or, 
duced from them, among my other natural cu- 
riofities, 
Fiaving thus enumerated the infects that pro- 
perly belong to my fourth order, I hall finally 
add to it all the Nymphs of thofe Worms of the 
firft, fecond, third, and fourth orders, which 
are changed into the faid form of Nymphs, 
within the bodies or fkins of other Worms, of 
Caterpillars, Nymphs, or Chryfallides, as like- 
wife thofe changed within the feveral excrefcen- 
ces of trees and their leaves, in form of warts, 
galls, and the like. However, I muft obferve, 
that I do not rank fuch Nymphs in the fourth 
order, as having any further right to it, than 
that of becoming Nymphs, like the Worms 
which really belong to it, in an obfcure, hidden, 
and myfterious manner. A perfon muft have 
great experience in thefe little creatures, to be 
able to {peak of them with certainty in their | 
whole hiftory. - 
In the eleventh place, I likewife reckon of 
this order, all thofe genuine Nymphs which are 
to be found within the body or fkin of any 
Worm or Caterpillar, and are the offspring of 
Worms, which have preyed upon the flefh of 
that Worm or Caterpillar in which they are 
found. ‘Thus it now and then happens, that a 
Worm or Caterpillar, not having ftrength enough 
to caft its fkin, becomes hard and firm, without 
Jofing any thing of its external form; in which 
cafe, the worms that have hid themfelves in it, 
devour all its flefh, and being freed in this man- 
ner from any neceffity of altering their fituation, 
they change there to genuine Nymphs, and af- 
terwards to Flies. Sometimes a fingle Worm of 
an extraordinary fize poffefles himfelf in this 
manner, of the whole body of another larger 
Worm, and without ever leaving it, becomes 
therein a Nymph, and afterwards a Fly. But if 
the Caterpillar fhould retain vigour enough, not- 
withftanding fuch cruel treatment, to throw off its 
external fkin, and reach the ftate of a Chryfalis, 
then the body of fuch Chryfalis becomes the 
fcene of all the foregoing mutations. 
‘What ought to be confidered as a greater 
paradox than all, is, that thefe Worms fome- 
times defert the body or fkin of the Caterpillar, 
upon which they had hitherto preyed, and upon 
deferting it, enclofe themfelves in an oviform 
web, within which, they at length change to 
real Nymphs, and afterwards into Flies. I thall 
have an opportunity of treating this fubject more 
at large, when, if it pleafe God, I come to pu- 
blith my felect obfervations ; fo that at prefent, 
I do not pretend to treat of this change in a par- 
ticular manner. 
Twelfthly, I refer to this fourth order thofe 
genuine Nymphs, which become fuch from 
Worms, within the fkins or bodies of Chryfal- 
lides, in the fame manner with the Worms of 
our third order, and firft method; but I mean 
only fuch Nymphs as are found fingle in the 
Chryfallides corroded by them. 
I have obferved, that thofe Nymphs are of 
many and various kinds, and indeed fo different 
one from another, that it would be a difficule 
task to defcribe them fo as to be diftinguithed 
SORTER) ae eee each 
