The 8 OOK “of 
the other three divifions, namely, the 12, 13, 
and 14th, contains the inteftinum rectum et 
craflum, or the thick and ftraight gut. As the 
ftomach has a great number of fmall air-tubes, 
fo the inteftines have alfo the fame, but moft 
efpecially the rectum, which has vaft numbers 
of them, where its two mufcles, Tab. XV. 
fig. 1. 27, which force out the excrements are 
fituated. 
As the food of this Worm is mud or clay, 
the ftomach and inteftines are ufually found 
filled with it. This mud is found almoft always 
to fhew itfelf both through the ftomach and 
inteftines, and indeed through the whole body, 
but more particularly fo in the back. And 
hence, as the body is fo tranfparent, it follows, 
that the Worm does not appear to have always 
the fame colour, fince the mud is fometimes 
paler, fometimes greener, and fometimes more 
flefh-coloured, as it is more or lefs digefted or 
’ changed in the ftomach and bowels. 
As the time approaches when the Worm is 
to undergo its final change, and put on the 
form of a flying infect, no more mud is found 
in its inteftines. The fame likewife happens 
in the Coffi or Worms of Beetles, and in Bee- 
Worms and Silk-Worms, as alfo in other in- 
fects, for they all at that time become clear as 
chryftal. Some infects are all their life-time 
tranfparent, fo that their veffels, the vifcera, 
and their motions may be at all times feen and 
diftinguifhed in the body. | 
Of the inward parts of the Ephemerus, the 
moft worthy of notice are the pulmonary 
tube, and the afpera arteria trachee or wind- 
pipe, Tab. XIV. fig. 1. aa, asit is called in 
birds and quadrupedes, and in the human {pe- 
cies. This trachee does not proceed in the 
prefent infect from a fimple trunk, as in man 
or other animals, but confifts of two principal 
trunks, which are placed on each fide of the 
body running in a ferpentine manner, nor are 
they diftributed in the breaft only as in us, but 
throughout the head, belly, legs and wings, 
fo that by their means the ftomach and intef- 
tines, together with the mufcles and nerves, are 
all fupplied with air. As this appears to us 
a very wonderful thing, becaufe we do not 
underftand the reafon of it, it moft evidently 
teaches us how devoutly and religioufly we 
ought to adore God in all his prodigious works, 
which are equally inexhauftible and impene- 
trable. 
The pulmonary tubes * in this infect, as well 
as in the others that I have examined, confift 
of innumerable little rigid and curled parts, 
which are artificially joined together like twifted 
or fpiral rings, and are fo clofely linked to each 
other by the help of their tender and delicate 
invefting membranes, that they can eafily re- 
tain the air, and convey it to all parts of the 
body. 
tio 
New Ue RFs 6F, 
When the Worm changes its skin, I fhould 
imagine that thefe palmonary pipes likewife 
caft their covering, though I have never hi- 
therto been able to fee it; for at the time when 
I began thefe experiments no fuch thing ap- 
peared tome. ‘The change or calting of the 
skin of thefe pipes is fo remarkable in Silk- 
Worms, that it amazes the underftanding ; for 
in the very fhort fpacé of time wherein that 
creature’ cafts its skin, fome hundreds of thefe 
pulmonary pipes in the infide of its body, cait 
alfo their tender little skins, which are all com= 
pounded of fuch twifted rings. 
The colour of thefe pulmonary tubes or 
pipes is like that of mother-of-pearl, but fome- 
what inclining to gray; but the more frequently 
the skin is changed, it becomes by degrees of 
a clearer and more tran{parent whitenefs. They 
are therefore much whiter in the flying crea- 
tures than in the Worms which precede them. 
They are diftributed through the whole body, 
in order to convey the air, which they carry as 
well tothe internal as external parts of the 
infect. Hence thefe two moft confiderable and 
remarkable trachez, Tab. XIV. fig. 1. aa, 
which are placed in the Worm on each fide of 
the body, diftribute their ramifications and 
branching air-pipes all over it; that is, in the 
head towards the nerves and brain 64; in the 
thorax ec to the mufcles of the legs and wings; . 
in the abdomen dd dd to the obliquely afcend- 
ing and ftraight mufcles, as alfo to the fpinal 
marrow eee; and to the {mall guts or feminal 
veficles fff of the male; to the hairy bran- 
chiz or gills gg; to the ftomach, Tab. XV. fig. 
v. c, and the inteftines, Tab. XIV. fig. 1. 6; 
to the {kin 77; to the coat of the wings £2; 
to the ovary, Tab. XV. fiz. 1. //: in the fe- 
male alfo to the coat that invefts the ovary mm ; 
to the eggs themfelves. fig. vir. 2, as is feen 
when they are taken out of the body, and even 
to the heart itfelf. Fig. 1v.o0. £7, 
Ihave found it a difficult matter to difcover 
the external aperture of thefe pulmonary pipes, 
fince they do not openinto the mouth or throat, 
as in other creatures. For which reafon the 
nearer they approach the head, the fmaller they 
become, when it would be natural to f{uppofe they 
would become larger and more capacious. At 
length, after repeated inveftigations, I perfwade 
myfelf that I obferved that the little apertures 
or entrances of thefe pipes opened underneath 
in the fide of the breaft ; almoft in the fame 
manner as I afterwards difcovered them alfo in 
Locutfts, in which laft mentioned infect thefe aper- 
tures may be eafily feen. But as the Ephemerus 
lives in water and mud, therefore its trachexe 
muft be opened by narrower orifices, on which 
account it is more difficult to difcover them. 
From thefe experiments it appears moft 
evident, why the Worms of the Ephemerus or 
Day-Fly, when the water of the river increafes, 
* The doétrine of thefe pulmonary tubes in infe€ts has been confirmed by all fucceeding obfervations: the latter authors only 
have changed the names of thefe veflels, and their openings on the furface of the body. They call the tubes trachex, and 
the apertures on the furface of the body, which this author terms puncta refpiratoria, they call. fligmata. This laft term, 
though more modern, is exceptionable ; for ftigmata is ufed in botany to exprefs the heads of the ftyles in flowers, and pure 
philofophy condemns this equivocal ufe of terms. 
rife 
