O22 
in this, that the Nymph remains hidden under 
its fkin, which it never cafts; nor does it even, 
at any time, -prefent itfelf externally to view: 
that is, this Nymph lies hid in its Nymph, in 
the fame manner as the little creature of the 
firft order does in its egg, in which it is like- 
wife an invifible Nymph; or as the Worms of 
the fecond and third order, which are likewife 
invifible Nymphs in their eggs; or, laftly, as 
the Worm of this fourth order, which is like- 
wife an invifible Nymph, while in its egg. 
The eggs of all the four orders entirely agree, 
in general and in particular, with the change of 
the Worm of our fourth order into a Vermi- 
form Nymph. 
Having confidered fufficiently what has been 
faid, I fhall proceed to explain how it happens 
that the Worms, belonging to this fourth order 
of changes, do more or lefs deviate from the 
original form of the Worms, though they do 
not by any means caft their ikin. 
explain this clearly and diftinétly, I muft firft 
obferve, that fome of the Worms which be- 
long to the fourth order of changes, are pro- 
vided with hard, tenacious, and ftrong fkins; 
and others, on the contrary, have thin, foft,, 
and flexible fkins. This diverfity of fkin not 
only makes the tranfmutation of form more or 
lefs remarkable, but renders it fo obfcured in 
the Worms invefted with a foft fkin, that it 
becomes entirely incomprehenfible and inex- 
tricable. On the other hand, when the Worms 
are covered with a hard fkin, we fee nothing 
of this kind happens; for as their external 
tenacious {kin cannot form and accommodate 
itfelf to the internal change, which the body 
of the enclofed Nymph undergoes, that fkin 
neceflarily retains the figure of a Worm, and 
refembles it as exactly as if it were full alive. 
When the Worms, which I have referred to 
the firft fpecies or method of the fourth order 
of changes, have eaten fufficiently, and their 
limbs are increafed to the proper degree under 
the fkin, they feek a proper place for them- 
felves, wherein they may fately and quietly 
iffue intoa Nymph. After this they reft for 
fome time, until they infenfibly lofe all their 
former motion. But they are not even then 
confiderably contracted, nor do they become 
fmaller, or are they changed in form ; though, 
in the mean time, they put on the form of a 
real Nymph within their uncaft fin. 
| Hence, therefore, we draw this important 
conclufion, that the infenfible per{piration, 
which I have afferted to obtain univerfally in 
the Nymph, may, in this example, be feen, 
as it were, with our eyes: for, in the Worms 
of this firft fpecies, it is obferved, that the 
Nymph fills the whole fkin of the Worm. 
Bat this Nymph afterwards, changing colour 
in a manner not perceivable by the fenfes, and 
contracting itfelf by degrees, inwardly recedes 
on each fide from the extreme ends of the 
fin, and confequently then fills only a part of 
it. And this procefs continues, until the 
Nymph, being more and more contracted, by 
reafon of the evaporation of the fuperfluous 
In order to - 
The <B.OrOre. of NATURE; of, 
humours, manifeftly forms in the uncaft fkin 
of the Worm two very confpicuous cavities, 
one towards the head, and the other towards 
the tail and belly of the faid Nymph; and 
thefe cavities become afterwards larger. and 
larger, until the creature has acquired its per- 
fect ftrength. The very experienced Dr. Har- 
vey has obferved fomething like this, con- 
cerning the little cavitv in hens new-laid eggs; 
for this alfo is infenfibly inlarged afterwards, 
by the evaporation of the fluids. f 
Wherefore, when the skin is hard and tough 
in thefe Worms, or when it grows fomewhat 
hard at the time the Worm is inwardly obtain- 
ing the form of a Nymph, the former figure 
of the Worm muft neceffarily remain entire: 
whilft, in the mean time, the little creature 
puts on the form of the Nymph within the 
hardened skin, from which it is more. and 
more infenfibly feparating; as I fhall after- 
wards very clearly demonftrate, in the figures 
of my fourth order. The feveral obfervations 
which I fhall fubjoin to thefe, will indeed ren- 
der this matter yet more clear and intelligible; 
for I prefume boldly to appeal to thofe obfer- 
vations particularly, fince I have employed 
thereon all the induftry I was capable of. 
As to the fecond method of the changes in 
this fourth order, it comprehends thofe Worms 
which are covered with a foft skin; and it of- 
fers one thing to be confidered particularly, 
which is, that the external skin accommodates 
itfelf to the body of the Nymph which is in- 
wardly changed. But becaufe this internal 
tranfmutation of the little Body or Nymph 
becomes of the fhape of an egg, in many fpe- 
cies of thefe’ Vermiform-Nymphs, therefore 
the external skin alfo, which is not. caft off, 
then neceflarily acquires an egg-like figure: 
By this means thefe Worms alfo are changed 
into fuch Nymphs as do not caft their skin. 
The Nymphs, which are fubject to this method, 
are very complicated and difficult to be known, 
beyond all the reft of the fourth order, as their 
Worms have a very delicate and tender fkin. 
Thefe Nymphs, for that reafon, recede lefs 
from the form of their Worms than thofe in 
which their fkin is fomewhat thicker; fo that 
the hardnefs or thicknefs of the fkin makes the 
change plainer, or more obfcure to us. 
However widely thefe Nymphs differ from 
the prior form of their Worms, they all pre- 
ferve various traces of that form. In the firft 
place, they retain the fkin uncaft; and the an- 
nular incifions, the head, tail, and the reft, 
are preferved or altered, according as they more 
or lefs deviate from the form of Worms. Some 
alfo have appearances like legs, horns, and 
other marks. For thefe important reafons, I 
give them all promifcuoufly the name of Ver- 
miform-Nymphs ; though I very well know 
that they have been called eggs by fome induf- 
trious fearchers into nature, as Mouftet, Goe- 
daert, the illuftrious Mr. Ray, and lately by 
the very learned Francis Redi, as if no diftinc 
limbs could. be obferved inthem. But are not 
thefe the very Worms themfelves, which have 
5 within 
