alfo from the eyes, and no more perform their office. The muf-
cles o f the rings alfo in like manner, and a great part o f the pulmonary
points of refpiration, are feparated from the external
fkin. Thus the whole body contrails itfelf by degrees into a
fmall compact mafs. A t this time the gullet and the pulmonary
tubes caff a coat within the fkin. T o make this evident, it is.
neceffary to open the abdomen, when the pupa, it’s parts, together
with the caft off pulmonary pipes, may be clearly feen.
An exaft account of all the changes of the interior parts is to
be found in Swammerdam’s Book of Nature. Thefe changes are
belt examined by taking the pupa out o f the fkin, or outfide cafe,
when it begins to harden; for as it has not then quite attained the
pupa form, and the members are fomewhat different from what
they will be when in that flate, it is more eafy to obferve their
refpective fituation, than when the pupa is Tome days older, and
has loft the greateft part o f the fuperfluous humours. The pupa
is inclofed in a double garment; the interior one is a thin membrane,
which in veils it very clofely; the other, or exterior one,
is formed of the outermoft hard fkin of the larva, within which it
performs it’s changes in an invifible manner: it is this fkin which
gives it the appearance o f the larva while in the pupa ftate.
When the time approaches that the hidden infefil, now in the
pupa form within it’s old covering, is to attain the imago, fly, or
perfect ftate, which generally happens in about eleven days after
the preceding change, the fuperfluous humours are evaporated by
infenfible perfpiration. • The little pupa is contrafted unto the
fifth ring of the fkin, and the four laft rings o f . the abdomen are
filled with air, through the aperture in the refpiratory orifice o f
the
the tail. This may be feen by expofing the pupa a little while
to the rays of the fun, and then putting it’s tail in water, when
ypu';will find it breathe ftronger than it did before, and, by ex-
preffing an air-bubble out of it’s tail,; and then fucking it in again,
will manifeftly perform the afilion of infpiration and exfpiration.
The anterior part o f the pupa is drawn back from the fkin, and
having partly deferted it, the beak, head, and firft ring of the
breaft, the little creature lies Hill, until it’s . exhaling members
have acquired ftrength to burft the two membranes which
furround it.
I f the exterior cafe is opened near this period, a wondeiful
variety o f colour may be perceived through the thin fkin which
inverts the pupa. The colours of many of the different parts are
now changed; fome parts from aqueous become membranaceous,
fomeflefhy, and others cruftaceous. The whole body becomes in-
fenfibly fhaggy, the feet and claws begin to move: the variations
may be accurately obferved by opening a pupa every day until
the time of change. For this purpofe they fhould be laid on
white paper, in an earthen difh ; they fhould alfo be made fomewhat
moift, and be kept under aglafs : the paper feryes the pupa
to fix it’s claw to, when they come forth in the form of a fly, A
little water fhould be poured into the difh, to keep the pupa from
drying and fuffocation.
When the fly begins to appear, the exterior fkin is feen to
move about the. third and fourth anterior ring; the infe& then
ufes all it’s efforts to promote it’s efcape, and to quit the interior
and exterior fkin at one and the fame time. The exterior fkin is
divided into four parts; the infeft immediately afterwards breaks
open