The BOOK of 
The anatomy of 
Havin G thus fuccinétly defcribed the 
external conftruction of this Caterpillar, 
Jam now to exhibit and demontftrate its in- 
ternal parts. The firft thing that prefents itfelf, 
on opening the back of this infect, is the blood, 
which flows freely from it. This is of a tran{- 
parent green, and may be made ufe of as a 
paint for that purpofe; though, as it dries by 
being expofed to the air, it lofes much of its 
original luftre, and by degrees turns yellowith. 
There next appear, immediately under the 
fkin, thé mufcular fibres, which ferve to move 
the rings of the body. On railing of thefe 
fibres, the fat appears, as likewife the heart, 
known by its panting motion: this I {hall pre- 
fently defcribe. On the hinder part, upon the 
back, and between the laft rings of the body, 
there are two fpots or particles, with fome 
divifions in them, Tab. XXXIV. Fig. 111. not 
unlike the kidneys of men or quadrupedes. 
On opening thefe {pots, they are found to con- 
tain fome veffels, and to have a connexion 
with the lower rings, by means of fome flender 
filaments, and certain pulmonary tubes. In 
my opinion, thefe particles do not attain their 
full growth and perfection, till the infect be- 
comes a Butterfly. This appears plainly enough 
in Silkworms, whofe tefticles {pring from this 
part. 
have to fay, on this fubject, for my defcription 
of the Butterfly, as they appear only in an 
embryo-ftate in the Caterpillar. — 
Removing the parts already mentioned, we 
come at the ftomach. This almoft entirely 
fills the Caterpillar’s body ;_ and, though it be 
fo very capacious, is always as full as it can 
hold, the infect being extremely voracious, fo 
that it hardly ever defifts from eating a fingle 
moment. During this part of its life, it feems 
entirely confined to the two operations of 
taking in its food, and difcharging its excre- 
ments; by which means it acquires its proper 
fize in a few days. The gullet, Fig. rv. a, is a 
{mall and flender tube, which running from 
the forepart of the ftomach to the mouth, 
through a flit in the fpinal marrow, juft under 
the brain, and growing larger and larger in its 
progrefs, it forms a communication, for the 
infeGt’s food, between the mouth and ftomach. 
I have reprefented only a few of the pulmo- 
nary tubes, 5544, in the forepart of the fto- 
mach, where they appear like fo many veffels, 
elegantly difperfed over its furface, and fupply 
it with the vital air from every fide. Amongtt 
thefe tubes is to be feen a tendinous ligament, 
ec, which runs, both above and below, from 
one end of the ftomach to the other. It arifes 
from the tendons of the mufcular fibres. be- 
longing to this part. Thefe mufcular fibres 
are feen diftinétly through, and I have repre- 
fented them on each fide of the ftomach, dd d; 
' but, to avoid confufion, I have been obliged to 
leave out the pulmonary tubes, that are to be 
I thall therefore referve what more I 
NAACT UR R Hs 208, 
the Caterpillar. 
feen in the infect in the fame place. The fto- 
mach confifts of three coats. The outward | 
coat, upon which the pulmonary tubes are 
diftributed, is very thin: the next is thicker, 
and mufcular ; the third, which immediately 
contains the fubftance that is to be digefted, is 
very delicate like the firft. 
On the upper and lower parts of the fto- 
mach are placed fix clofed guts, which, de» 
fcending towards the thick gut, there termi- 
nates in little tubes, that have no paflage. 
Thefe fix little guts, which are here reprefented 
out of their natural fituation, by returning upon 
themfelves, and running back towards their 
origin, form, as it were, twelve inteftines; fo 
that, on parting them from the ftomach, and 
difpofing them orderly along its fides, there 
appear fix on each part. ‘Thefe little guts arife 
on each fide, from a trunk, in form of a knot, 
Tab. XXXIV. Fig.iv. ff, which {prings from 
the inteftine that immediately fucceeds the 
ftomach ; and then again, being divided into 
fix tubules, thefe run back towards the thick 
inteftines, gg, again{t which they are folded 
and curled in a moft furprifing manner, 44. 
One of the thick inteftines, z, in which the 
excrements are reduced to form, is here repre=. 
fented alfo; and this thick inteftine ends, in, 
the rectum, or ftraight gut, &. 
On removing the ftomach, there appear very, 
plainly two little canals, Fig. v. aa, which before 
had feveral windings, and lay again{t the fides. 
of the ftomach. Thefe canals afcend to the 
forepart of the head, where I) traced them 
very high, as far as the brain; but could fol- 
low them no further, fo that I cannot affign 
their abfolute origin. On the forepart they 
are very fine and flender, 4; but afterwards 
dilate greatly, c, till at laft they terminate in 
two fharp filaments, ¢, which have their in- 
fertion near the ceeca, or clofed inteftines. 
It is no eafy thing to determine the ufe of 
thefe little parts from the diffeCtion of the Ca- 
terpillar: to pretend to guefs at it, would be 
folly. Our bufinefs is to find out the inten- 
tions and operations of nature, not to contrive 
them. At firft, I took thefe for the filk-bags 
of the Caterpillar, on account of their great 
refemblance to thofe of the Silkworm. But I 
was afterwards convinced of my miftake, by 
finding them unaltered in a Caterpillar, that 
had made its web. This circumftance may 
ferve to convince us, that they muft be of fome 
ufe to the future Butterfly. 
The real filk-bags of the Caterpillar are not 
more than one fourth part fo large as the vef- 
fels, which at firft paffed upon me for fuch; 
for the Caterpillar {pins but very little; and I 
have therefore orhitted, as not much worth 
notice, the repofitories of the matter with 
which nature has fupplied her for that purpofe. 
After the foregoing parts have been exa- 
mined, the fat becomes confpicuous. This 
fubftance, 
