THE EYE. 



751 



Vig. 306. 



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

 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.," Ileilk., 1852) it would appear 

 to be dissolved by boiling in water. The epitheliiun of the capsule is 

 placed, not on the outer surface, as Br'iicke 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 0-006-0-01 of a lino, with 

 round nuclei. After death its elements are readily separated, expand 

 into transparent spherical vesicles, many of which burst, and together 

 Avith a few drops of aqueous humor which have penetrated into the in- 

 terior, constitute the so-termed aqua Morgagni, which during life, when 

 the epitltelium is accurately applied to the surface of the lens^ does not 

 exist at all. 



The lens itself consists entirely of elongated, flat, hexahedral ele- 

 ments, 0-0025-0-005 of a line broad, and 0-009-0-0014 of a line 

 thick, of a perfectly transparent aspect, very flexible and soft, and 

 havino; a considerable degree of 

 toughness, which have usually 

 been described as the fibres of the 

 lens, although they are nothing 

 more than tliin-ivalled titles with \' 

 clear, viscous, albuminous con- \ 

 tents, which, when the tubes are 

 torn, escape from them in the 

 form of large irregular drops, and 

 consequently might suitably be 

 described as the tubes of the hms. 

 As concerns the microscopic cha- 

 racters of these bodies, they are 

 distinguished by the circumstance 

 of their becoming opaque and 

 more distinct in all reagents by 

 which albumen is coagulated; con- 

 sequently, reagents of that kind, 

 particularly nitric acid, alcohol, 

 creasote, and chromic acid, are especially suitable for the investigation 

 of the leiis ; but in caustic alkalies they are quickly dissolved, and 

 they are also speedily attacked by acetic acid. The union of the tubes 

 which are more solid, slender, and opaque in the more compact inner 

 layers of the lens — the so-termed nucleus — than in the softer external 

 portions, is brought about simply by their apposition. They invariably 



Fig. 300. — Fibres or tubes of the lens. 1, from the Ox, with slightly toothed borders; 2, 

 transverse section of the lenticular tubes of Man. — Magnified 350 diameters. 



