XXX 
T AB. XXVIIL 
RVG, 
Lhe brain and fpinal marrow of the Coffus. 
a The brain, with the four nerves that it 
produces. 
6 Two origins of the fpinal marrow at fome 
diftance afunder, but meeting lower to form 
one trunk. 
ddd Nerves ifluing from the fpinal marrow. 
Por Gr lis 
Al recurrent nerve, as is appears through the 
microfcope. 
aa The origins of the recurrent nerves, cut 
off in that place where they iffue from the 
brain. 
66 Recurring nerves, tending upwards; their 
afcent may be feen on each fide of the in- 
fect’s gullet. 
ec Elegant inflections of the recurrent nerves. 
d The firft nodule formed by the recurrent 
nerves after their union. 
e A recurrent nerve again changed to a fingle 
one. 
f The fecond nodule of a a recurrent nerve. 
g Small nerves branching from a recurrent 
nerve. 
FIG. Of. 
The fpinal marrow of a Silk-Worm when about to 
enter the Nymph fiate, the better to fhew the 
difference between its fpinal marrow and that 
of the Coffus. As likewife what little reafon 
 fome people have to confider every dilatation of 
the marrow as a diftinct brain. 
a ‘The brain. 
666 123, &c. The fpinal marrow, confitt- 
ing of twelve globules or nodules, which 
are formed as it were by the union of twelve 
pair of nerves iffuing from the brain. 
cc A pair of nerves running to the eyes. 
dd A confiderable part of nerves iffuing from 
the firft nodule of the marrow, and tending 
towards the mufcles of the head, teeth, and 
other parts. Every one of thefe nerves form 
by itfelf a beautiful nodule. 
ee Two of thefe nodules. 
Jf A pair of very fine nerves iffuing from the 
brain, or origin of the {pinal marrow. 
g The recurrent nerves in their natural fitua- 
tion, with the two nodules belonging to 
them, and the nerves arifing from the faid 
~ nodules. 
6 A pair of nerves-arifing from the firft nodule 
of the marrow, and running towards the 
little bags that contain the juice of which the 
filk is compofed, like a glutinous liquid. 
This pair of nerves ferves perhaps to animate 
the moving and extruding fibres of the faid 
filk bags. 7 
A Short Explanation of the TA BL E S. 
zz Two pair of elegant nodules, formed by 
nerves that proceed from the brain, and firft 
nodule of the {pinal marrow, and are diftri- 
buted chiefly towards the mufcle of the 
head. ft 
kkk Four pair of nerves which iflue from 
the very origins of the marrow, and by no 
means from itsnodules. In my opinion the 
origin of all the other nerves is like this, as 
more particularly appears in the nerves of 
the Silk-Worm Butterfly, in which the fub- 
ftance forming the nodule is of a different 
nature from that of the fpinal marrow, fo 
that the whole is enclofed in the latter merely 
for the fake of procuring it greater firmnefs. 
In man, the origin of whofe marrow confifts 
likewife of two parts, the nerves arife in like 
manner from the nervous part of the mar- 
row, which is full of fibres, and after pra- 
ceeding a little way beyond the faid ner- 
vous part, and growing fomewhat longer, 
they every one of them unite to form fuch 
nodules at different diftances from their ori- 
gin. The fame difpofition is obfervable 
even in quadrupedes. On placing the warm 
marrow of thefe infects on cold {pring water, 
it hardens to a confiderable degree, and very 
plainly exhibits its fibres, and the heteroge- 
neous matter, of which it is formed. This 
circumftance I have reprefented by a great 
many curious drawings, done after nature, 
in Dr. Slade’s houfe, from a fpinal marrow, 
publifhed by Dr. Blafius with his book of 
Commelyn. But this laft gentleman added 
the defcription. My name was not men- 
tioned on this occafion, becaufe fome other 
Gentlemen, who affifted me in the diffection, 
not choofing to have their names made pub- 
lick, I thought it improper that mine fhould. 
It is likewife very remarkable, that in men and. 
brutes, the pia mater, enclofing the medul- 
lary fubftance that iffues like a fine filament 
from the marrow, in order to form a nerve, 
lies fo clofe and firm about the nerves, that it 
is {carce, if atall poffible, to penetrate into 
its ramifications with the fineft threads that 
glafs canbedrawninto. And as this narow- 
nefs is ftill increafed by the medullary fub- 
ftance, it is eafy to guefs how {ubtile that 
matter muft be, which flows through thefe 
and other nerves, and is only reftrained by 
that very fine membrane called the pia ma- 
ter, I therefore firmly believe, that this 
matter, called the animal fpirits, is not to be 
gathered or contained by any vefiels, and is, 
for that reafon, altogether invifible. 
But that thefe little nerves fhould be in no dan- 
ger of entangling one with another, or dif- 
placed, the Author of Nature has contrived — 
that they fhould form various nodules; and 
that each of them, at its origin, fhould, in 
men, as well as beafts, be connected by that 
delicate membrane, which forms the third 
coat of the brain, and is called, by us, 
arach- 
