562 WASTE-PRODUCTS 



than cystine. Among the constituents of the neutral sulphur fraction 

 may be enumerated Sulphocyanides which are found in traces in the 

 urine and also in the Saliva, Chondroitin-sulphuric Acid, and a number 

 of poorly-defined nitrogenous acids which have been designated the 

 Oxyproteic Acids. 



In rare instances Cystine is found to occur in the urine in notable 

 quantities, as much as 0.5 to 1.5 grams being excreted in one day. 

 This condition, known as Cystinuria, is a much more serious abnor- 

 mality than alcaptonuria, which it resembles in being due to a defect 

 of metabolism, because the large excretion of this sparingly soluble 

 amino-acid often leads to the formation of deposits or calculi in the 

 bladder. According to Garrod, cystinuria is a rarer disease than 

 alcaptonuria, but it reaches the physician more frequently because 

 of the serious natiire of the symptoms which arise. The failure to 

 oxidize cystine, which is characteristic of the cystinuric patient, fre- 

 quently extends to other amino-acids, and amines, such as Cadaverine 

 and Putrescine, derived from the decarboxylation of Lysine and Orni- 

 thine may also appear in the urine, and occasionally, leucine and 

 tyrosine. In such cases cystinuria is evidently an expression of a 

 general defect of the deaminizing-mechanism. 



An experimental cystinuria may be induced in animals by the 

 administration of halogen-benzenes, such as monochlorbenzene or 

 monobrombenzene. The halogen-benzene is paired with cystine and 

 excreted in this form as Mercapturic Acid, in combination with glu- 

 curonic acid. The excretion of cystine in these cases is accompanied 

 by a diminution of the output of inorganic sulphates. 



The presence of cystine in the urine may be suspected if hexagonal 

 crystals are deposited which are soluble in ammonia and insoluble in 

 acetic acid. If a few crystals are dried, placed on a slide and covered 

 with a cover-glass underneath which is introduced a drop of strong 

 hydrochloric acid, as each crystal is touched by the acid a cluster of 

 fine prisms is seen to spring from it, consisting of cystine hydrochloride 

 (Wollaston's Test). 



In passing it may be stated that the Phosphorus of the diet is wholly 

 or almost wholly excreted in the form of phosphates in the urine and 

 the feces. 



URINARY PIGMENTS. 



A variety of urinary pigments have been described by different 

 investigators, but only three pigments have been definitely character- 

 ised. These are Urochrome, a pigment to which the yellow color of 

 urine is mainly due, Urobilin which is voided in the form of a colorless 

 chromogen, Urobilinogen, which is converted into urobilin by exposure 

 to air under the influence of light, and Uroerythrin, which is frequently 

 but not invariably present. 



On saturating urine with ammonium sulphate, urochrome remains 

 in solution while urobilin is precipitated. When a solution of urobilin 



