ii PRIMARY DISSOCIATION-PRODUCTS 63 



cutaneously behaved similarly. If large quantities of cystin, dissolved 

 in soda, are injected rapidly into a peripheral vein, some thio- 

 sulphate but mostly cystin was found in the urine. By injecting 

 cystin into a mesenteric vein and so forcing it to pass through the 

 liver, he showed that the generally accepted theory as to tauro- 

 cholates resulting from the union of taurin and cholalic acid need not, 

 of necessity, be the only possible one, by bringing forward chemical 

 proof that direct compounds of cystin and cholalic acid are possible, 

 and that cystin-cholates may be oxidised secondarily into taurocholates. 

 Starting with this idea, Simon and Campbell l made experiments on a 

 person suffering from cystinuria, to see whether this complaint could 

 not be cured by the administration of cholalic acid. Their results were 

 negative, and hence they arrive at the conclusion that in cases of 

 cystinuria either no synthesis of cholalic acid and cystin takes place 

 with subsequent conversion into taurocholate, or that cystin is not 

 converted into taurin. Kothera, 2 experimenting on himself, found 

 that both calculus-cy stin and hair- cystin, taken in doses of 1 gramme per 

 day, were completely recovered from the urine as sulphates. " Larger 

 doses were purposely avoided in order that bacterial action in the 

 intestine might not complicate the issue. Thus cystin, dissolved in 

 nutrient gelatine and inoculated with Bacillus coli communis, is broken 

 up with liberation of sulphuretted hydrogen even under anaerobic con- 

 ditions. This . . . explains the different results obtained by Blum 

 and by Wohlgemuth with rabbits ... for Wohlgemuth used large 

 quantities of cystin, only portions of which were absorbed : the rest 

 undergoing decomposition in the intestine might well account for the 

 thiosulphate in the urine." 



That the mercapturic acid which is found in dog's urine after 

 feeding with benzene chloride and benzene bromide is derived from the 

 same cystein which is found in proteid-cystin, and that the mercapturic 

 acid is not a derivative of a-thiolactic acid, Friedmann has shown in a 

 third paper. 3 The mother substance of mercapturic acid has the 

 acetamide in the a- and the mercaptane in the /^-position. 



CH 2 . (SX) CH . NHCOCH 3 COOH. 



The occurrence of taurin in lower animals has been investigated 

 by Agnes Kelly. 4 



1 C. E. Simon aucl D. G. Campbell, Hofmeisters Beitr. 5. 401 (1904). 



2 C. H. Rothera, Journ. of Physiol. 32. 175 (1905). 



3 E. Friedmann, ffofmeister's Beitr. 4. 486 (1904). 



4 Agnes Kelly, ibid. 5. 377 (1904). 



