CYSTINURIA 523 



When the fluid was carefully filtered the precipitation of cystin was de- 

 layed several days. Evaporation did not increase amount of cystin. 

 He concludes: 



1. That the simple addition of an acid in which cystin is not soluble 

 is not sufficient to separate cystin from the urine and that the theory 

 held as to the state of combination of cystin in the urine is probably 

 inaccurate. 



2. That a compound exists in certain urines which under the in- 

 fluence of fermentation yields cystin. 



3. That the fermentation is due to the growth of a large organism 

 probably a torula. 



4. Cystin occurs in kidneys and liver, showing fermentation may 

 go on in the system. 



Benziger, reporting his failure to synthesize cystin, wrote that with 

 isocyanic acid cystin yielded a uramide acid which upon dehydration 

 yielded hydantoins. Cystein is so seldom found in the urine because it 

 oxidizes so easily to cystin. (Mathews and Walker.) From cystein, the 

 benzyl derivative can be easily prepared by shaking benzoylchlorid with 

 potassium hydroxid for one-half to one hour. 



What the cause of cystinuria is has remained a puzzle to students of 

 metabolism. That it is a derangement in catabolism is the general opinion, 

 where the seat of derangement is not known. It is supposed that cystin 

 is always produced in normal catabolism, but it is immediately broken 

 down to other sulphur derivatives. Wohlgemuth stated that cystin was the 

 antecedent of the sulphur bodies in the urine and of taurin in bile. When 

 he allowed cystin to decompose with meat, he obtained a yield of hydrogen 

 sulphid, methyl mercaptan, and ethyl sulphid, which are usual constitu- 

 ents of the intestinal gases. 



Since Wollaston's case of cystinuria, many cases have been reported. 

 In 1876, Niemann(a) (6) collected all the cases reported of cystinuria that 

 he found in the literature. We shall cite him : 



CASES 



Sex Age 



Boy 5 years 



Man 36 years 



Man 30 years 



Man] -p 30 years 



Y Brothers on . 



ManJ 30 to 49 years 



1P The identity of hair cystin and horn cystin was confirmed by Gaskell. In five 

 cystin stones from St. Bartholomew's Hospital Museum the cystin was only found in 

 the form of hexagons. Tyrosin was not present in them. 



