198 On a Fermentation causing Separation of Cystin. [Feb. 20, 



II. "On a Fermentation causing the Separation of Cystin." 

 (Preliminary Communication.) By Sheridan Delepine, 

 M.B., B.Sc. Communicated by T. Lauder Brunton, M.D., 

 F.R.S. Received February 13, 1890. 



During the months of March and April, 1889, I analysed for 

 Dr. Lauder Brunton, and under his direction, a number of speci- 

 mens of urine containing cystin. The estimation of the amount of 

 this substance present in the samples examined was carried out by 

 Lobisch's process, and revealed certain variations which were of 

 interest as connecting the elimination of cystin with the processes 

 of digestion. In carrying out this work, I was struck with the fact 

 that the amount of cystin precipitated from the same specimen was 

 greater under certain circumstances than under others. Thus, 

 (1) when specimens were strongly acidified with acetic acid, as recom- 

 mended by Lobisch, the precipitation took place more slowly than 

 if the specimens were allowed to undergo a spontaneous acid fermen- 

 tation (which never caused the reaction to become very strongly acid). 

 (2.) When the fluids were carefully filtered, the precipitation of 

 cystin was delayed, often for several days. (3.) When a specimen in 

 which cystin had begun to separate was carefully filtered, the precipi- 

 tation was interrupted for several days. (4.) When portions of a 

 urine which was proved by collateral experiments to contain cystin 

 were kept at a temperature of 60° C, no cystin could be separated 

 afterwards by the usual processes. (5.) Evaporation did not seem to 

 increase materially the amount of cystin obtainable from a given 

 specimen. (6.) The largest amounts of cystin could be obtained by 

 allowing the specimens to stand at the ordinary temperature for several 

 days, provided the precipitate was separated whilst the urine was still 

 acid. (7.) A similar amount of cystin could be obtained more rapidly 

 by keeping the fluid at a temperature of less than 40° C. for twenty-four 

 to thirty-six hours. (8.) When a drop of urine from which cystin 

 was being deposited, and which contained a large number of bacteria 

 and torulse, was added to a carefully filtered portion of the same urine, 

 a deposit of cystin occurred in the filtrate thus inoculated in twenty- 

 four hours, the urine becoming at the same time full of bacteria and 

 torulse, while another portion of the same filtrate not inoculated de- 

 posited no cystin for ninety-six hours. I venture to suggest as the 

 most probable explanation of the above results — 



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

 soluble is not sufficient to separate cystin from the urine, and, there- 

 fore, that the thejry generally held as to the state of combination of 

 cystin in the urine is probably inaccurate. 



