336 THE EYE. 



The function of this ligament appears to be purely me- 

 chanical. 



Ciliary processes, (Fig. 99.) Dissection. Continue the 

 circular incision made in the sclerotic, through the choroid, 

 and on looking into the anterior half of the divided eye 

 from behind, there is seen a radiated disc of perfectly regu- 

 lar form., surrounding the crystalline lens, which from its 

 resemblance to a radiated flower, is called the corona ciliaris. 

 The several rays of this crown constitute the ciliar} r pro- 

 cesses. 



These processes are delicate folds of the choroid mem- 

 brane, extending from the ciliary ligament to the posterior 

 surface of the iris, and forming a ruffle on the forepart of 

 the vitreous humor, around the circumference of the crys- 

 talline lens. They are small, triangular in shape, about 

 sixty or seventy in number, according to Zinn, and from a 

 line to two lines in length. Between each pair of these 

 processes, a corresponding one from the hyaloid membrane, 

 extends into and fills up the spaces; thus forming a kind 

 of dove-tailing union, which completes the posterior wall of 

 the aqueous chamber, and prevents the fluid from, flowing 

 back in that direction. 



The ciliary processes are covered with the pigment. If 

 this be washed off, they are seen to be very vascular, of a 

 grayish color, and continuous with the choroid. 



Function. Various opinions are entertained as to the 

 use of these processes. Some believe them to be muscular, 

 and to have the power of regulating the focal distance of 

 the eye. Others suppose that they consist of a venous 

 erectile structure, and are connected with the motions of the 

 iris. Others, again, say that they secrete the aqueous hu- 

 mor while others think, with more plausibility, that they 

 secrete or furnish the black pigment with which they are 

 covered, to arrest any superfluous rays which may enter 

 the eye. 



Iris, (Fig. 99.) This organ, so called from the variety 

 of its color, is situated behind the cornea and in front of 

 the lens, and is seen suspended as a perpendicular curtain, 



