CH. LVIIL] 



THE LENS 



813 



The lens is made up of a series of concentric laminae (fig. 511), 

 which, when it has been hardened, can be peeled off like the coats of 



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FIG. 509. Section through the eye carried through the ciliary processes. 1, Cornea; 2, membrane of 

 Descemet ; 3, sclerotic ; 3', corneo-scleral junction ; 4, canal of Schlemm ; 5, vein ; 6, nucleated 

 network on inner wall of canal of Schlemm ; 7, lig. pectinatum iridis, a & c ; 8, iris ; 9, pigment of 

 iris (uvea); 10, ciliary processes ; 11, ciliary muscle; 12, choroid tissue; 13, meridional, and 14, 

 radiating fibres of ciliary muscle; 15, ring-muscle of Miiller; 16, circular or angular bundles of 

 ciliary muscle. (Schwalbe.) 



an onion. The laminae consist of long ribbon-shaped fibres, which in 

 the course of development have originated from cells. The fibres 



Fia. 510. Ciliary processes, as seen from 

 behind. 1, Posterior surface of the iris, 

 with the sphincter muscle of the pupil ; 

 2, anterior part of the choroid coat ; 3, 

 one of the ciliary processes, of which 

 about seventy are represented. 



FIG. 511. Laminated structure of 

 the crystalline lens. The laminae 

 are split up after hardening in 

 alcohol. 1, The denser central 

 part or nucleus ; 2, the succes- 

 sive external layers. *. 



(Arnold.) 



are united together by a scanty amount of cement substance. The 

 central portion (nucleus) of the lens is the hardest. 



The epithelium of the lens consists of a layer of cubical cells 

 anteriorly, which merge at the equator into the lens fibres. The 

 development of the lens explains this transition. The lens at first 



