Axis of th€ Chry ftallin, and to reunite more exadly in a point, 
then in the Eyes of moft other Animals, which have their C/&(?- 
rotidts white towards the Axis oi Sight, and by confequence 
lefslenfible of light, who in recompence can very much dilate 
the Pupilla of their Eyes when they ftand in need of a great 
lights but alfo their Sight is not fo diftind, becaufe the 
RayeSj which fall on the Extremity of the Chryftallinejdo inter- 
fedl the Axis too near in their refradion. 
It is true, that to fupply in fome fort this defed, they have a 
little Chryftalline in the middle of the great one, and this little 
Chryftalline being of a more fpifs confidence then the great one, 
its refradion is alfo more ftrong, and makes the rayes, which 
come from one point in the Axis znd pafs near ? he Center of the 
Chryftalline to refra<S more then it there had been but one 
Chryftalline. And by this means the greateft part of the 
Rayes, which fall upon the Extremity of the great Chryftalline, 
do interfeftthe Axis^, which caufes their fight to be lefs con- 
fufed, although it be never fo diftind as that of Men and Birds, 
which have but one Chryftalline. Fijhes have alfo a double 
Chryftalline, for otherwife their fight would be more confufed 
than that of other Animals who live in the Air, for their Chry- 
ftalline being fpherical,the rayes cut tht Axis more unequal- 
ly than if it were lenticular and its convexities were of a grea- 
ter fphere 5 and it ought necefifarily to be fpherical, becaufe 
therefradiionof the Rayes, which pafs from the water into the 
Chryftalh'ne, is very ftnall, and would make \x.%focm too far 
diftant if the Chry ft Uine were lenticular. 
The difficulty of your Second objedion proceeds alfo from an 
Ambiguity of words, and confiHs in knowing, what we are to 
fay it is,that has a great continuity and communication with the 
Brain. My Hyfothefis is, that the Nerves are all coated with 
theF/4 Mater (which envelops all the Spinal Marrow) and 
have with it the fame continuity of fibers 5 fo that if thefe 
nerves be never fo litre moved, the impreffion is carried to the 
Brain by the Continuity of thefe fibers-, and whether it be^ 
that the texture is diflerent in Nerves of different fenfes5 or 
that they contain fome fpirituous liquors which determine their 
