fenfations, by fome differences they have among thcmfelves 5 
it is certain, that the Nerves of Sight, in what manner foever 
they are moved^ reprefcnt Colours and Lights? thofe of Hear- 
ing, Sounds, 3nd thofe of the Touch, Paines^&c. 
Now ihtChoroeides is an Expanfion and dilatation of the Pin 
Mdter^ which enveloppes internally the Optique Neive, and 
which comes from the tuberofity of the Spinal Marrow, by a 
continuity of -fibe s 5 whence it follows, that how little foever 
t\\QChroades be toucht, the impreflionmay beeafiiy comma* 
nicated to the brain: And to the end^ that the fame thing may 
be faid of the Retma^ there maft be a little channel in the Optic 
nerve, through which the Retina in its proper Subftance ex- 
tends it felf to this tuberofity b^^ a continuity of Fibers 5 which 
isnotfeen, andyou are conftrainedtofay, that there are little 
filaments of nerves which come from the interiour of the Op- 
tickj andexpandthemfelves through the Retina, which have 
this continuity 5 but if there were thefe filaments, they fliould 
fpread themfelves through the Retina^as from a Center to a Cir- 
cumference, and ihould lye clofer together near the Optick 
nerve, than a good way farther in the Retinas which nevcrthe« 
lefs we do not obferve to be fo. 
Befides, ifyouthruftapin through the thicknefs of theReti- 
na,y ou will often meet with filaments 5 but if you look on them 
through a Convex glafs, you will difcover, that they end in lit- 
tle veffels of Veins and Arteries, which are in the Retina 5 and 
infallibly, if there were any nerves, you might find them in the 
famemanner^ and they would ftop the Pin, fince they are as 
hard and firm as the little Arteries; and when you fay^ that one 
may diftinguifli thefe filaments in the water, becaufe the reft of 
the Retina difappears , fthat is repugnant to experience, and 
to what you have faid before, viz. that the Retina may be feen 
all whitein the water, and without tranfparency 5 and you ought 
to fliew thefe filamentSj orelfe we ihali take^ them for , a thing 
invented at pleafbre. 
* You bring after that two Experiments 5 the f!r(i of which is^ 
that if an aperture be made on the upper part of th^ Eye , we 
may difcover thePidure of the Obje£ls on the anterior furface 
oi thG Retim-j butif this aperture be made in the white of the 
Eye, 
