734 



THE EYE. 



the surface, but in the foetal lens throughout, and towards the centre of the 

 lens in the adult, they are three in number, diverging from each other like rays 

 at equal angles of 120. The lines at opposite poles have an intermediate 

 position (not being over one another) : they are the edges of planes or septa 

 projecting vertically inwards to the centre of the lens, and receiving the ends 

 of the lens-fibres which are collected upon them. 



Fig. 484. OUTLINES ILLUSTRATING THE COURSE OP THE FIBRES IN THE POSTAL 

 CRYSTALLINE LENS. | 



This diagram represents the typical or more simple state of the fibres in the full- 

 grown foetal or infantile condition ; the three dotted lines radiating at equal angles of 

 120 from the centre indicate the position of the intersecting planes, where they reach 

 the surface; the figures 1, 2, 3, 4, 5, and 6, indicate certain fibres selected arbitrarily at 

 equal distances in one- sixth part of the lens to show their course from the front to the 

 back ; A, the anterior surface ; B, the posterior surface ; C, the lateral aspect : in these 

 several figures, for the sake of clearness, a few lines only are introduced into the upper 

 third, while in the lower two-thirds a greater number are marked ; but no attempt is 

 made to represent the number existing in nature ; the parts of the dotted line marked c, 

 are on a level with the centre of the several lenses. 



p. 4 gg Fig. 485. FRONT VIEW OF THE FIBROUS 



STRUCTURE OP THE ADULT LENS (from 

 Sappey after Arnold), f 



In this figure more numerous planes of 

 intersection of the fibres are shown than 

 in fig. 484. 



STKUCTUKE. When the lens has 

 been dried, or hardened by immer- 

 sion in spirit, boiling water, or other 

 fluid capable of rendering it firm 

 and white, concentric laminae, nar- 

 rowing to a point at the poles, may 

 be detached from it. The laminae 

 are further composed of microscopic 

 fibres, which adhere together by 

 wavy or slightly serrated margins. 



The lens is albuminous in its composition, and is devoid of blood-vessels ; 



and at the planes of intersection a finely granular homogeneous material 



takes the place of the fibres. 



