URINE 



NEUTRAL SULPHUR COMPOUNDS 



409 



Under this head may be classed such bodies as cystine (see page 74), 

 oxyproteic acid, alloxyproteic acid, uroferric acid, methyl mercaptan, 

 ethyl sulphide, thiocyanates and taurine derivatives. The sulphur 

 content of the bodies just enumerated is generally termed unoxidized 

 or neutral sulphur in order that it may not be confused with the acid 

 or oxidized sulphur which occurs in the inorganic sulphuric acid and 

 ethereal sulphuric acid forms. Ordinarily the neutral sulphur content 

 of normal human urine is 5-25 per cent of the total sulphur content 

 (see "Sulphur Partition" in chapter on Metabolism). The actual 

 amount excreted may be 0.2-0.4 grams per day, calculated as SO 3 . 



FIG. 131. ALLANTOIN, FROM CAT'S URINE. 



a and 6, Forms in which it crystallized from the urine; c, recrystallized allantoin. (Drawn 

 from micro-photographs furnished by Prof. Lafayette B. Mendel of Yale University.) 



Its origin is mainly endogenous. The excretion is fairly constant for 

 any given individual in spite of dietary changes. In tuberculosis, 

 cancer, cystinuria, etc., the amount may be relatively or absolutely 

 increased. (See page 422 for test for neutral sulphur.) 



NH.CH.NH 



ALLANTOIN, OC 



CO 



NH.CO NH 2 



Allantoin is found in the urine of practically all mammals including 

 man. In human urine it occurs in very small amount (5-15 mg. per 

 day) whereas in the case of all other mammals investigated except 

 anthropoid apes, it is the principal end-product of purine metabolism 



