THE LENS. 



123 



yield gelatin. Its chief constituent is inucin, or mucinogen (Young), 

 called mucoici by C. T. Morner. According to the latter, this inucoid con- 

 tains 12-27 nitrogen, and 1*19 sulphur, per cent. There are also small 

 quantities of proteid. References to the papers of Young and Morner, 

 the most recent workers on this subject, will be found on p. 62. 



The lens. The following are the results of Laptschinsky's 1 

 analyses : 



Water . 

 Solids . 

 Proteids 

 Lecithin 



63-50 per cent. 

 36-50 

 34-93 

 0-23 



Cholesterin 2 



Fats 



Salts 



0-22 per cent. 

 0-29 



0-82 



FIG. 20. Absorption spectra of retinal pigments. 1, of visual purple ; 2, of visual yellow ; 

 3, of xanthophane in ether ; 4, of rhodophane in turpentine ; 5, of chlorophane in 

 ether. This diagram inatic way of representing absorption spectra indicates the thick- 

 ness of the absorption-bands in solutions of different strengths ; the top of each 

 spectrum shows the thickness of the bands in a dilute solution ; as the concentra- 

 tion of the solution increases, the bauds become wider, as in the lower part of each 

 diagram. After Kiihne. 



The proteid matter is thus very abundant ; it is chiefly a globulin, to 

 which Berzelius gave the name of crystallin. It has also been the 

 subject of researches by Hoppe-Seyler, Laptschinsky, Kiihne, and C. T. 

 Morner. 3 According to the last-named investigator, about 52 per cent. 

 of the proteid matter of the lens is insoluble in water and saline 

 solutions. The insoluble proteid residue is an albuminoid, and it is 



1 Arch.f. (I. cjes. PhysioL, Bonn, Bd. xiii. S. 631. 



2 The cholesterin increases greatly in cataract (Calm, Hoppe-Seyler's " Phvsiol. Chem.," 

 S. 692). 



3 Ztschr. f. physiol. Chem., Strasslmrg. Bd. xviii. S. 61. 



