112 



A. I. RIXGER 



second illustration of the body's ability to utilize split products of protein 

 for synthetic purposes. The hair and nails of animals are especially rich 

 in cystin and no doubt a certain proportion of the eystein goes into the 

 formation of these continually growing cells. 



The greatest portion of the sulphur fraction of the eystein molecule 

 is oxidized to a sulphate state and excreted in the urine in the form of in- 

 organic salts. A small proportion of the oxidized sulphur combines with 

 ethereal substances like cresol, phenol and ihdoxyl, probably for detoxieat- 

 ing purposes, and is excreted in the urine, while a third portion of the 

 sulphur reaches the urine in an unoxidized form (neutral sulphur), prob- 

 ably in the form of taurin, small traces of eystein, sulphoeyanid, etc. 



Lysin is completely burned in the body without leaving any clue as 

 to the path of catabolism. It does net give rise to either glucose or acetone 

 bodies in the intermediary stages. After deamination it may pass through 

 a glutaric acid stage. 



COOII 



o 



CH 



CH 



CH 



Deamination 



and Oxidation 



CHXH 



CIL 

 CH 2 - 

 CH 2 

 COOH 



As yet unknown 

 process of combustion. 



COOII 



Lvsin 



CO 2 



Glutaric acid 



Arginin is first broken up into urea and ornithin. This is accom- 

 plished by a ferment arginase which is found in the liver, kidneys, intes- 

 tinal mucous membranes, thymus and muscles. (Kossel and Dakin, 11)04 : 

 and 1905 ; Otto Riesser, 1906 (a) ; Charles Richet, 1894 (e)). 



CH, + CO 



CH, 



CHNHo 



\NIL 



COOH 



Arginin 



COOH 

 Ornithin 



Urea 



