118 THE AMINO ACIDS 



tery, gastro- enteritis, etc. Their origin in putrefaction 

 of protein decomposition products together with their 

 appearance in the urine of cystinurics led to the view 

 that the cystine in the cases mentioned had a like source. 

 This, however, has been shown to be incorrect. A 

 second view was that diamines interfered with sulphur 

 oxidation in the organism, hence the appearance of the 

 unoxidized cystine. This idea has been shown to be 

 untrue for cystinuria may occur in the absence of the 

 diamines, and the administration of diamines has no 

 influence upon the output of cystine in the urine. "In 

 intestinal disturbances, it is probable that these com- 

 pounds are the result of bacterial activity indeed, they 

 may be the metabolic end-products eliminated by bac- 

 teria. In cystinuria, however, it is possible that a dif- 

 ferent explanation for diaminuria is pertinent. It may 

 be assumed, for instance, that in the beginning cysti- 

 nuria and diaminuria are brought about through a 

 similar, or indeed the same cause, or causes, for 

 example, a gradually changing type of metabolism 

 induced by some unknown agency, resulting in an 

 anomaly of metabolism. If the anomaly is slight in 

 character, cystine alone is eliminated as a result, 

 whereas if the change in metabolism is sufficiently pro- 

 nounced diamines are also excreted. If this assump- 

 tion is accepted it is easy to explain why in some cases 

 of cystinuria the diamines are absent, and that gradu- 

 ally one or both of these compounds disappear, that 

 cystinuria persists, but that cystinuria does not cease 

 and leave diaminuria." 



