Ther How Sot O RLY. of Tanrsri css 
rife likewife higher, and go to other cells, for 
they very frequently want frefh air to breathe. 
And for the fame reafon, when the water is 
, lower, they muft be likewife found to defcend 
deeper ; for they would then become too dry, 
and their cells or habitations would be dried and 
fhut up. 
The pulmonary pipes hitherto defcribed 
cannot, in any infect, be examined better than 
in the Worms, when they have been dead fome 
days, as their vifcera are then growing black; 
for then they exhibit a very beautiful appearance 
to the eyes, becaufe they are of the colour of 
mother of pearl, or filver when cleaned by 
boiling; alfo, as they confift of a fomewhat hard 
and firm fubfance, fo that they do not foon 
putrefy: hence they alfo retain at that time their 
form and roundnefs, 
If the breaft and belly.of thefe worms be 
viewed with a microfcope, the whole abdomen 
is feen to be interwoven with white filver-co- 
floured vefiels. In order to difcover whether 
there be really any air in thefe veflels, they muft 
be put into a little drop of water, and preffed 
with the point of a needle, for thus the enclofed 
air will immediately fhew itfelf. When thefe 
infects are diflected under water, and fome of 
the pulmonary pipes are cut off with a fine pair 
of {ciffors, they immediately rife to the furface 
of the water; the fame thing may be feen about 
their broken ramifications, the extremities of 
which are then carried upwards. In a Worm 
that has been dried, having been divided 
in the middle, thefe air-pipes are moft eafily 
- difcovered, becaufe they always in that cafe re- 
main open from the force of their curled rings, 
though all the other parts grow perfectly 
hardened. 
Amongft the many things which may be 
obferved concerning thefe pulmonary tubes, it 
is particularly worthy of notice that fo great 
a number of them are diftributed towards the 
-branchia, Tab. XIV. fig. 1, or gills, fo that 
three principal branches pp of the air-veffels 
may be feen in thofe which I have reprefented 
as cut off: the middle one of thefe branches 
is alway blackith gg, except in the centre of 
it, which is whitifh and tranfparent ; the other 
two run on either fide of the middle black one, 
and diftribute a large number of filver-coloured 
veffels g¢z through the branchiz or gills. Thefe 
veffels are not well diftinguifhed by their co- 
lour, becaufe the fix branchie or gills, ‘Tab. 
XII. fig. 1v. ff, through which they are con- 
veyed from each fide of the body, are white 
and very tranfparent. Under thefe, on each 
fide, are obferved five rowing fins, Tiab. XIV. 
fig. 1. rrr, of a yellow colour, by the help 
of which the Worm {wims. 
I made during my diffeGtions fome further 
obfervations on thofe branchiz and their veffels, 
butas I do not know where the papers are, the 
obfervations have alfo entirely flipped out of my 
memory. Hence I am ignorant what ufe that 
feathered little part ss is of, which is feen un- 
der the firft as yet entire pair, and whether 
Lit 
it be likewife found about the other branchize 
or gills. Neither do I know the proper com- 
munication between thefe branchie and the air- 
pipes, Tab. XV. fig. 1v. 00, between the latter 
and the heart ¢z. I cannot therefore fay any 
thing more with certainty concerning them 
than what may be gathered from the figure. 
I omitted, to prevent confufion, delineating 
in this all the air-pipes which are about the 
heart, having exhibited fome of them only 
entire, and others cut off or broken v v. 
Indeed, in my figures I have not always ob- 
ferved the proportional magnitude of the parts, 
fince I looked upon that as a work of great 
labour and little ufe, and therefore I have not 
{crupled fometimes to delineate one part larger 
than another. Befides, I never intended to pub- 
lith thefe experiments, without being firft re-- 
vifed; and this I have afterwards thought the 
more neceffary, becaufe from that time I ac- 
quired a greater knowledge of the parts of thefe 
infects, and became more capable of afcertain- 
ing their anatomy. I hope the benevolent 
reader will kindly pardon the imperfections of 
this work, which I muft confefs are innumer- 
able; for what man is able to defcribe, even 
with the uninterrupted labour of many years, 
all the miracles that are to be met with in this 
little infect. 
The heart, Tab. XV. fig. 1v. ¢¢, is found 
to be placed in the upper part of the body in 
the back, as it isin Silk Worms, Bee Worms, 
Coffi, or Worms of Beetles, Caterpillars, and 
other infects of that nature. It is fomewhat 
protuberant «xx in feveral places, and it is fo 
in Silk Worms alfo, as has been obferved by 
the diligent Malpighius. But this author does 
not feem to me, as far as I can learn from my 
own experiments, to have fairly from this drawn 
his conclufion that this infect has more hearts 
than one. I have difcovered the motion of the 
heart but very inaccurately in the Ephemerus, 
and only in that part of it which There repre- 
fent in the figure; but I have entirely forgot, 
againft which of the annular feCtions it was 
placed in the back. . 
The fpinal marrow, Tab. XIV. fig. 1. y yy, 
is wonderful and very worthy of notice in this, 
as it is in all other infects that I have diffeéted ; 
it confifts as of eleven knotty tubercles, fome- 
what long and oval. The firft of thefe knotty 
little parts ferves inftead of a brain, out of 
which * * the optic nerves may be very diftiné- 
ly feen to arife and fpread themfelves. In 
the fame manner I have obferved, that the reft 
of the nerves iflue from the ten fubfequent 
little knots ; but thefe that arife from the lower 
knots, are not fo numerous as thofe from the 
upper. The fpinal marrow is moreover found 
to be here and there beautifully ftrengthened 
with ligaments 2%, which are compofed partly 
of a ftrong horny fubftance, and partly of tendi~ 
nous wreaths or fafcie. This is the cafe in the 
breaft in particular, for there the {pinal marrow 
fends out a great many nerves to the mutcles, 
a¢, 8, which move the legs and wings: the 
. fame 
