CHAP. XI.] PERIPHERAL NERVOUS END-ORGANS. 453 



The giobu- Under the name of Crystallin, Berzelius described 



lin contained the proteid belonging to the group of globulins which 

 forms the chief solid constituent of the crystalline lens. 

 This substance is soluble in water holding oxygen in solution, forming 

 an opalescent liquid, which is precipitated by C0 2 . According to 

 Laptschinsky 1 , acetic acid does not precipitate this body, which, how- 

 ever, separates in a flocculent form when its solution is heated to 

 70 C. According to this author the lens behaves fibrinoplastically : 

 according to Kiihne it does not possess that property. 



The cornea becomes opaque after death ; it is believed (Kiihne) 

 that this is not due to any coagulation of a soluble proteid, but to 

 diffusion phenomena, leading to the formation of vacuoles in the 

 lens-fibres, which necessarily impair the passage of light. 



Results of The following are the results of four analyses of the 



analyses^! crystalline lens of the ox, made by Laptschinsky. 

 the lens. Proteids in 100 parts . 34'93 



Lecithin . . . . 0'23 



Cholesterin . . . 0'22 



Fats .... 0-29 



Soluble salts . . . 0'53 



Insoluble salts . . 0'29 



The following are the results of other analyses of the lens of the 

 ox made by Hoppe-Seyler and Laptschinsky. 



Hoppe-Seyler Laptschinsky 



Proteids in 100 parts . 33'03 . . 3472 



Aqueous extract . . 0'94 . . 0'95 



Alcohol extract . . 0'52 . . 0'37 



Insoluble salts . . 012 . . 0'17 



Soluble salts . . . 0'61 . . 0'50 



Ash obtained on incinerating) . QQ 



the aqueous extract j 



Ash obtained on incinerating) A . _ - ., 



the alcoholic extract j U ' U 



Ethereal extract . . 0'45 



Changes of By introducing solutions of salts or of sugar under 



the lens in the skin of frogs a form of cataract is induced in which 

 cataract. ^ e structure presents vacuoles ; these have been pro- 



duced apparently by the abstraction of water from the lens ; the 

 cataract which occurs in the course of some cases of diabetes is proba- 

 bly induced in this way. 



In genuine cataract the more common change consists, however, 

 in a fatty degeneration of the lens in which cholesterin is abundantly 

 deposited ; occasionally it is said that the lens is the seat of a depo- 

 sition of calcareous salts. 



i Laptschinsky, Ein Beitrag zur Chemie des Linsengewebes. 



