50 . oTheo BOLO R jaf” NGRON U eR: EF ‘or, 
ftripped of its outer covering ; for at that time 
the motion of the heart appeared to me fo plain, 
and was withal fo confiderable, that Ifaw it dif- 
place a particle of fat in one of its vibrations. 
The end of this powerful organ, when it is 
fattened to the tail, is a little fharp and nar- 
row, but here and there it dilates itfelf, Tab. 
XL. Fig.1v. aa. ‘Towards the head it gra- 
dually widens 44, and then clofes again into 
a natrow channel c, in which form, after paf- 
fing through the abdomen and thorax, it pur- 
fues its courfe towards the head, where it is 
intimately united with the membranes of the 
brain. ‘Thus, in regard of figure, the heart of 
this Worm nearly reprefents the Worm itfelf, 
except the part next the head, being a great 
deal narrower, and that next the tail, dilating 
itfelf here and there, as in Silkworms. 
On opening either the Worm or Nymph, the 
motion of the heart prefently ceafes ; and if 
it did not, the particles of fat with which it is 
furrounded, would hinder us from feeing it. 
For this reafon, the beft time for examining the 
heart of this infect, is when it has attained the 
Fly-ftate : or if we choofe to do it in the Worm, 
we ought firft to leave it for fome time in fpi- 
rit of wine, that the fat may gradually diflolve 
and wafte away ; but at this time, the heart is 
fo delicate as not to fuffer any air to get into it. 
In the beginning, I really thought I {hould ne- 
ver be able to difcover or difclofe this part ; and 
I muft own, that human ignorance and weak- 
nefs never appeared fo evident to me, as during 
my furvey of this little infect; for with all my 
attention and diligence, I found it impofiible 
to examine it as minutely as I propofed, tho’ 
I {pared no time to get the better of all the dif- 
ficulties that oppofed my inquiry; the won- 
ders I difcovered in it, being but a {mall part 
of thofe accumulated miracles I have here re- 
lated. This my infufficiency has made me 
very often, in the courfe of my inquiries, break 
out within myfelf into the following words :--- 
O God, thy works infinitely furpafs the reach 
of our feeble underftandings; all that we ac- 
tually know of them, or ever can know, is 
but a faint and lifelefs thadow of thy adorable 
perfections. The brighteft underftandings fail 
in the contemplation of them, and are obliged 
to confefs, that all this boafted penetration is 
but fhort-fightednefs, when employed in fa- 
thoming the depths of that power, goodneds, 
and wifdom it has pleafed thee to exert in the 
loweft parts of thy creation ! 
The truth of thefe words evidently appears 
by the conftruction of the brain, {pinal mar- 
row, and nerves of the Worm here under con- 
fideration, which lam now going to defcribe ; 
for this conftruGion is fo wonderful, that I 
doubt very much, whether any thing equal to 
it was ever before obferved in any animal. 
The brain confifts of two globular lobes, ‘Tab, 
XL. Fig. v. aa. Thefe lie upon the gullet ; 
and for this purpofe nature has contrived a flit 
6 in the fpinal marrow for the gullet to pafs 
through. On the forepart of the head appear 
the membranaceous parts of the eyes cc, which 
gradually expand themfelves along with the 
optic nerves that are to ferve the fucceeding 
Fly, and grow till they are arrived at their juft 
period of increafe. In the mean time, thefe 
membranaceous rudiments of the Fly’s eyes 
are curled and folded up, and cannot be feen 
but very imperfectly, becaufe the infect has not 
as yet attained its Nymph-ftate, in which at 
laft all thefe parts unfold themfelves, and be- 
come very difcernible. 
The fpinal marrow confifts of eleven no- 
dules dd, which form the moft elegant {pecta- 
cle that nature ever exhibited ; for it is bent fo 
as to refemble a {wine’s tail, and runs as it were 
in curls from one end toanother. This curl- 
ing may be ftill confiderably increafed by cutting 
the nerves. ‘The figure I give of this part does 
not exprefs all the windings of the origi- 
nal, the better to exhibit the eleven nodules, © 
from whence all the other nerves take their 
rife ; for all the nerves of the infeé arife from 
the brain, the {pinal marrow, and thefe no- 
dules. In the firft place we are to name thofe 
nerves which tend to the forepart of the head, 
and running under the membranaceous rudi- 
ments of the future eyes ee, are diftributed to 
the gullet, the jaws, the mouth, and palate, 
to the Worm’s eyes, the mufcles of the legs, 
and parts thereabouts. Next are the nerves g 
which extend to the fides of the infect’s body. 
Laftly, there appears a confiderable number of 
them gg, that {pring on each fide from the 
eleven nodules of the fpinal marrow. To avoid 
confufion, I have omitted fome of them in the 
figure ; the laft mentioned ramificatiens go to 
the ftomach, inteftines, mufcles of the fkin, 
and all the other internal parts, which they 
fupply with motion, fenfe, and life. But how 
is it poflible to defcribe the fpirits contained in 
thofe nerves, and the manner in which the fe- 
cretion of fuch fpirits is performed ? For my 
part, I freely acknowledge, that as yet I have 
not been able to difcover for what purpofe the 
medulla fpinalis is curled up in this infect, 
while a Worm, in fo ftrange, but elegant a 
manner ;* whereas in the Nymph, and after- 
wards in the Fly, though neither of them are 
fo long as the original Worm, it appears ftretch- 
ed out toitsfulllength. It is in the eleven no- 
dules that the alteration is moft confiderable, 
for thefe in the Nymph and Fly (O incompre- 
henfible wonder!) are found at a greater dif- 
tance from each other, than they were in the 
Worm. ‘The nerves, on the contrary, from ly- 
ing at full length in the Worm, are curled up 
and folded in the Nymph and Fly, and are 
otherwife altered in a moft furprifing manner, 
as I {hall hereafter explain by a figure of the 
Fly’s {pinal marrow. ‘The tran{mutation, there- 
* As important as the {pinal marrow is to the animal ceconomy, we find that it does not obferve the fame courfe in all creatures, 
In the generality of animals it runs through the middle of the back-bone; but in fifhes in general, it is carried through certain pecu- 
liar apophyfes fituated on the upper part of the vertebra: we fee in how ftrange a manner it is difpofed in infects. ‘There cannot be 
a better fubje&t of inquiry for the naturalifls, than into the reafens of this varions caule, and the purpofes it anfwers. 
6! 
fore, 
