CRYSTALLINE LENS. 587 



of the lens contains 14.10 per cent N and 0.83 per cent S, and is a little 

 less soluble than that from DESCEMET'S membrane. 



The chief mass of the solids of the crystalline lens consists of proteins, 

 whose nature has been investigated by C. MORNER.* Some of these pro- 

 teins dissolve in dilute salt solution, while others remain insoluble in 

 this solvent. 



The Insoluble Protein. The lens fibres consist of a protein substance 

 which is insoluble in water and in salt solution and to which MORNER 

 has given the name albumoid. It dissolves readily in very dilute acids 

 or alkalies. Its solution in caustic potash of 0.1 per cent is very similar 

 to an alkali-albuminate solution, but coagulates at about 50 C. on nearly 

 complete neutralization and the addition of 8 per cent NaCl. Albu- 

 moid has the following composition: C 53.12, H 6.8, N 16.62, and S 

 0.79 per cent. The lens fibres themselves contain 16.61 per cent N 

 and 0.77 per cent S. The inner parts of the lens are considerably richer 

 in albumoid than the outer. The quantity of albumoid in the entire 

 lens amounts on an average to about 48 per cent of the total weight of 

 the proteins of the lens. 



The Soluble Protein consists, exclusive of a very small quantity of 

 albumin, of two globulins, a- and fl-crystallin. These two globulins differ 

 from each other in this manner: a-crystallin contains 16.68 per cent N 

 and 0.56 per cent S; /9-crystallin, on the contrary, 17.04 per cent N and 

 1.27 per cent S. The first coagulates at about 72 C. and the other at 

 63 C. Besides this, /?-crystallin is precipitated from a salt-free solution 

 with greater difficulty and less completely by acetic acid or carbon dioxide. 

 These globulins are not precipitated by an excess of NaCl at either the 

 ordinary temperature or 30 C. Magnesium or sodium sulphate in sub- 

 stance precipitates both globulins, on the contrary, at 30 C. These 

 two globulins are not equally divided in the mass of the lens. The 

 quantity of a-crystallin diminishes in the lens from without inward; 

 /?-crystallin, on the contrary, from within outward. 



A. BECHAMP distinguishes the two following protein bodies in the watery 

 extract of the crystalline lens: phacozymase, which coagulates at 55 C., con- 

 tains a diastatic enzyme, and has a specific rotatory power of ()/= 41, 

 and the crystalbumin, with a specific rotatory power of ()/= 80.3. From 

 the residue of the lens, which was insoluble in water, BECHAMP extracted, 

 by means of hydrochloric acid, a protein body having a specific rotatory power 

 of ()/= 80.2, which he called crystalfibrin. 



The lens does, not seem to contain any protein bodies which coagulate 

 spontaneously like fibrinogen. That cloudiness which appears after 

 death depends, according to KUHNE, upon the unequal changing of the 

 concentration of the contents of the lens-tubes. This change is produced 



1 Zeitschr. f. physiol. Chem., 18. This contains also the pertinent literature. 



