THE EYE. 



383 



— 0.01'", with round nuclei. After death its elements are 

 readily separated, expand into transparent spherical vesicles, 

 many of which burst and together with a few drops of aqueous 

 humor which have penetrated into the interior, constitute the 

 so-termed aqua Morgagni, which during life, when the epithe- 

 lium is accurately applied to the surface of the lens, does not 

 exist at all. 



The lens itself consists entirely of elongated, flat, hexahedral 

 elements, 0-0025— 0005'" broad, and 0-009— 0- 00 14'" thick, 

 of a perfectly transparent aspect, very flexible and soft, 

 and having a considera- Fi 306 



ble degree of toughness, 

 which have usually been 

 described as the fibres of 

 the lens, although they 

 are nothing more than 

 thin-walled tubes with 

 clear, viscous, albuminous 

 contents, 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 lens. 

 As concerns the micro- 

 scopic characters of these 

 bodies, they are distin- 

 guished by the circumstance of their becoming opaque and 

 more distinct in all reagents by which albumen is coagulated ; 

 consequently reagents of that kind, particularly nitric acid, 

 alcohol, creosote, and chromic acid, are especially suitable 

 for the investigation of the lens; 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 



Fig. 306. Fibres or tubes of the lens. 1, from tbe Ox, with slightly toothed 

 borders ; 2, transverse section of the lenticular tubes of Man ; x 350 diam. 



