( m ) 
is perfom'd chiefly in the Brain^ andthefe other parts are 
bat the tranfenm to it; but alfo becaufe in an Amaurhfis or 
guttaferena chefe parts are free from any ihdifpolition ( the 
^y.^ i^V'^^^xm^ without any fault j^.tbQ tfce 
fight u thm whoilyJoji and therefore thofe F^'^r^j; of ihe 
(5^?^^'i^iPrz/^? muft^^b^^ either byb be- 
ing obftruded.or the roots of 'em compreft (about ^ttha^ 
lamiOptici) by [ome tumur^ or too much pent in by aeon- 
tradlion and extenuation of the outward coats cf the Nervesj 
or by any Confufion or Contortion of the faid. Fibres. 
2. I (hew there that the fuperior Fibre in tzcb thalamus 
Opticus had the greateji tenfion^ and the inferior the leaft y 
as may appear from the fbrmer arifingfrom the^f^/^ofthe 
thalami 0/?^?W and having i the greateft' flexure thus O ; 
and xhQ latter arifing from the lomrpart oi the aforefaid 
thalami and having the leafi: flexure thus as may be. 
judg'd from a view of thofe parts in the Brain , fo that the 
Cprrefpondence of the former or latter in Jite and tenfion caus'd- 
that correfpondence or Vnion in Vifion. 
9. It may be farther noted that the intermediate orr 
lateral Fibres in . the farne Ey^e, tho diametrically oppofite 
to onq another, are faid to differ mtenfion Tby reafonof; 
a more confiderable flexure oi x\\t external ibtn tht inter- 
nal-^) whence two Stars or other bodies feen by the collateral- 
Fibm of the fame Eye ( whiift t' other may be Ihut J appear 
diflinft and apt as one, becaufe they are viewed by difcord: 
Vibrfs of that fame Eye • . which likewife is fo kept in its Or- 
iit by the invefiingparts, that it can't well be otherwife. 
4. I obferv'd that the Optic Nerves arofe feparately 
from thofe two Mplecuk of the brain, and befides have a~ 
pe^culiar advantage in rifing from ^^\t{t hillocks in this man- 
ner whereas the other Nerves arife from the bajis .oixb^ 
^^^Iniazflatter manner y and clofer together, fo that the ex-/ 
t ream differe nce of their rifeis very remarkable^ and in* 
(h) See Boner. Sepulchret, torn, i. /ib, i. Se^, 18. Ohferu.i, 
(c) S€€ Fig, iJn the frrrme^tio^edJColkCi.lJ. ' ' ' ^ v)H .'1^* f> (^) 
' tend- 
