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Anatomical Obfervations on the StruEltire of the Iris, Situation of 



the CrjfaJIine, (^c. 



After names fo refpedable and truly great as thofe of Heifler, 

 Petel, Morgagni and Winilow, one would naturally imagine that 

 nothing with refpeil to the ftrutture of the eye was left unex- 

 plored ; yet from the following account it will appear that much 

 was ftill wanting. I fliall not enter into a general defcription of 

 the eye, but on the prefent occafion confine my remarks to the 

 parts immediately interefted in the operation, and to the errors 

 committed in the defcription of them. And firft ; much confufion 

 has arifen on account of the two chambers of the aqueous hu- 

 mour, and very reprehenfible miftakes in the defcription and deli- 

 neation of the iris ; the iris is generally fuppofed to take its rife 

 from the fclerotica, at its jundion with the cornea tranfparens ; 

 but though this is exadly the cafe at the middle of tne fuperior and 

 inferior parts of the eje^ as it lies in the orbit, yet the adhefion of 

 the ligamentum ciliare gradually falls back on the fclerotica, as 

 it advances towards the two canthufes, infomuch that here the 

 origin of the iris is a mathematical line, pofterior to that of the 

 cornea tranfparens ; a remark of great coTife(juence to the operation, 

 hut particularly to the extraSlion of the cryftalline ; to prove this, if 

 you remove the cornea tranfparens, at its jundion with the fcle- 

 rotica, you v^ill evidently fee that the clofe adhefion between this 

 laft and the choroides, called ligamentum ciliare, is exadtly as 

 defcribed The uvea or iris is alfo reprefented as proceeding 

 exadly flat, from the edge of the fclerotica to its aperture called 



the 



