(61^) 
An OhfcYvation 
Concerning a Blemifli in an Horfes Eye^ not hitherto discover dhf 
any Author 5 which may ht of great ufe in the Choice of an 
fforfeto thofe who are Curious 5 made by Dr. Richard Lower 
At the Royal Society , January 23. 1 66], 
AMong the many defeSls and diftempers in the Eyes, the Eyes 
of Horfes are peculiarly affedled with one, which no Ani- 
mal befides is troubled withall ( as far as I have obferv'd ) nei- 
ther do I remember any Author hitherto to have taken notice of 
it 5 and that is a Sfungy Mxcrefcence (commonly of a dark muske- 
colour ) which grows out of the edge of that Coat of the Eye 
caird the Vvea-^ which Spungeif it grow large or increafein 
number ( as it frequently happens ) it depraves the fight very 
much, or totally intercepts it. But that you may more eafily con- 
ceive the manner,how it is done^you may remember,that the Uvea 
is a tnufculous part^the ufe of it being chiefly to contrail and dilate 
itfelf for theadmiflion of Objefts with as much light, as the 
Eye can conveniently bear; fo that, the brighter and more 
refulgent the light is, to which the Eye is expos'd, that Mem- 
brane contrads its felf into a narrower compafle^ and the more 
dark the place is, it delates it felf the more, as you may fee in a 
Cats eye more readily performed, than in any other animal^IhzvQ 
yet obferv'd ; So that;^ if that fpmgy fubftance, which growes out 
of the edge of the Uvea^ be fo great^or the number of them fuch, 
as that they grow in feveral places about the fupill of the Eye ^ 
where it contracts its felf, the pupil or fight is very much (if not 
totally) obftruded^ and confequently the Horfe fees very little 
or nothing at all: As f have many times taken exadl notice in 
fome Horfes, which being brought into the Sun- fhine, could not 
fee at all, but fuffer'd me to touch the fght of their Eye with my 
finger without the leaft winking-, whidi Horfes being led back 
into the Stable, the Uvea in that obfcure place dilating it felf, 
they could fee very well again, and would not fuflferme tofhew 
my finger near to the Eye without frequent clofing their Eye-lids 
and tofling their heads. The fame Horfes I underftood by the 
T 1 1 Owners 
