ORGANISATION OF THE IRIS. 



425 



Fig. 191.* dilating fibres, he has de- 



scribed on the front of the 

 iris, as consisting of irregular 

 shaped masses, placed in the 

 middle space between the 

 greater circumference and the 

 pupil, sending forward a num- 

 ber of little elevated lines or 

 tendons which terminate in 

 loops about the twentieth part 

 of an inch from the pupil, and 

 from which loops smaller stria? 

 converge to the edge of the 

 central opening. The whole arrangement, he says, is like that 

 of the columnce carnea and chordcs tendinece of the heart. 

 The examination of a hazel eye, in a living subject, or of an 

 iris, under water, seems in favor of his views. Believing the 

 iris to be muscular in its structure, I have practised an opera- 

 tion for the formation of artificial pupil where the iris has no 

 posterior adhesions, which has in eight cases, resulted in the 

 most complete success, and was attended with surprisingly 

 little irritation. After puncturing the cornea in the usual 

 method, I make an incision of two or three lines near the outer 

 margin of the iris concentric to the cornea so as to cut off at 

 their base a number of the radiating fibres. The inner portion 

 of the iris is next divided at right angles to this incision up to 

 the closed pupil. Immediately that this is done such action 

 ensues as seems to indicate the muscularity of the organ. The 

 inner circle of sphincter fibres divided across, contract, and as 

 the resistance which the radiated fibres previously made at the 

 point of division has been removed by their section at the outer 

 part of the iris, they form at once an oblong artificial pupil; 

 which is permanently preserved. In several cases this opera- 



* Fig. 191, is a very accurate representation, according to Professor Jacob, 

 of the posterior face of the iris, showing the eolumnse corneas and chordge 

 tendineae much magnified. The anterior surface of the iris presents a very 

 different appearance. P. 



36* 



