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The vitreous humour occupies all the pofterior and anterior part 

 of the eye as far as the iris, leaving a fmall focket or cavity in its 

 anterior part for the lodgment of the cryflallinc lens. It is faid 

 to be covered by a fine membrane, called tunica vitrea ; but 

 for my own part, who have diffeded as many eyes, and of dif- 

 ferent animals, as I believe any man, I confefs I have never 

 been able to trace any membrane furrounding it except in its 

 anterior part, and there it is covered very fenjibly and very re- 

 markably. Leaving then the defcription of this tunica vitrea to 

 thofe that can find it, I fhall obferve that when the vitreous 

 humour reaches the iris there is a clofe adhefion between them 

 by the intervention of a firm pellucid membrane ariling from the 

 infide of the choroi'des, exadly oppofite to that part where the 

 adherence between this lafl and the fclerotica commences, called 

 ligamentum ciliare. This membrane covers all the anterior 

 part of the vitreous humour j but when it reaches the focket or 

 cavity in which the cryftalline is contained it fcparates; the pof- 

 terior, and by much the finer part, lines this focket, whilft its 

 anterior one covers the cryftalline, fo that it becomes inclofed in 

 it as a nut is in its fhell. Thus the cryftalline is enclofed ia 

 a fine pellucid membrane, which capfula is conjtantly humeded 

 with a tranfparent liquor which prevents any kind of adhefion 

 or connexion between it and this interpofed body. Th?, 

 anterior part of this capfula is fo denfe as to be fometimes 

 capable of being feparated into tv;o diftinift coats ; the contained 

 liquor is, from its difcoverer, called Morgagnis liquor. 



I HAVE 



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