382 SPECIAL HISTOLOGY. 



what has been made known by Miiller and myself, but 

 it will still demand much time and pains before it can be 

 conducted to any certain results. Future inquirers should 

 take up particularly the relations of the radiating and optic 

 fibres in the eye, also the point whether the latter subdivide 

 in the retina, as is asserted by Hassall and Corti, and lastly, 

 whether the nerve-cells are directly connected with the nerve- 

 fibres (Corti) or not.] 



§ 228. 



The crystalline lens is a perfectly transparent body, in rela- 

 tion by its posterior surface with the vitreous humor, and late- 

 rally with the termination of the hyaloid membrane, the zonula 

 Zinnii; and in which are to be distinguished the lens, properly 

 so termed, and its capsule. 



The capsule of the lens consists of two elements — the proper 

 capsule and the epithelium. The former is a perfectly struc- 

 tureless and transparent, highly elastic membrane, enclosing 

 the lens on all sides, as if moulded to it, and parting it from 

 the neighbouring structures. If the lens with its capsule be 

 placed in water, the latter becomes considerably distended by 

 imbibition, whence it is apparent, that membranes of that 

 kind, notwithstanding their homogeneous structure, are yet 

 very permeable, so that the nutrition of the non- vascular lens 

 is provided for without difficulty, by means of materials 

 penetrating from without. The lenticular capsule, measuring in 

 its anterior wall, 0*005 — O'OOS"', and posteriorly to the attach- 

 ment of the zonula Zinnii, where it is abruptly thinned, not 

 more than 0'002 — 0'003'", may be readily torn, punctured, or 

 incised, whilst it offers considerable resistance to a blunt in- 

 strument. If an uninjured capsule be punctured, it contracts 

 to such an extent, owing to its elasticity, that the lens not 

 unfrequently escapes spontaneously. In its micro-chemical 

 reactions the capsule of the lens behaves exactly like other 

 transparent membranes, except that, according to Strahl 

 (' Archiv f. phys./ Heilk., 1852), it would appear to be dis- 

 solved by boiling in water. The epithelium of the capsule is 

 placed, not on the outer surface, as Briicke states, but on the 

 inner, towards the lens, lining the anterior half of the capsule 

 with a single layer of beautifully clear, polygonal cells, of 0006 



