IMPROVED. 109 



Membrane, and turn off very often one or more of 

 the Lamina: of the Cryftalline Humour ; nay I have 

 great Reafon to believe, that fome CataraBs arc no 

 inore than the Caffula of the Cryftalline grown 

 dark or opaque : for upon the leaft Touch with my 

 Needle ( I mean a flat two-edged Needle ) the Fi- 

 bres of the Capfula being a little divided, imme- 

 diately contra6led themfelves, and left the v/hole 

 Body of the Cryftalline clear and tranfparent ; and 

 I was fatisfied, it could not be the Cryftalline that 

 I touched with my Needle, becaufe I did it To 

 nightly that I fcarcely cut the Capfula. 



I fay, the Laminae of the Cryftalline Humour, 

 in the Difeafe called a Cataraft, are fo altered as 

 not to fufFer the Rays of Light to pafs through 

 them ; and when thefe Laminae, I mean the opaque^ 

 Strata or Lays of the Cryftalline, are thus fcraped 

 off with the Needle, it is then the remaining Part of 

 that Humour fuffers the Rays of Light to pafs thro', 

 although, indeed, they often rail in a confafed Man- 

 ner- upon the Retina ; and therefore it is abfolutely 

 necefl?.ry to fjpply the Defe6l of the Cryftalline, 

 which from being Convex, is, by the Needle in 

 couching, made almoft of a Plane Surface ; I fay, 

 this Defeat is beft fupplied by a Lens or Convex 

 Glafs. And for farther Proof that this is the real 

 Cafe of a Cataradl, and that the Cryftalline is in 

 Fa£l the true Lens of the Eye, it may be cbferved, 

 that thofe Perfons who have had their £}'C3 couched, 

 are obliged to ufe Glaftes of a greater Convexity, 

 than others who are above a hundred Years of Age : 

 And this, becaufe the Convexity of one Side of the 

 Cryftalline is fcraped off in the Operation of couch- 

 ing. But it is Folly and Madnefs to imagine, with 



T r the Oculift, that the Cryftalline Humour 



is quite tum'd out of the Cavity it makes in the Vi- 

 treous, in fuch Operation i and that the Vitreous 

 Humour becomes Convex in its Place. I fay, this 

 Is (for Reafons too plain to be infifted on) talking" 

 more like a Quacking empirical Fellow, than one 



Ycrfed 



