200 INDOXYLSULPHURIC ACID. 



2. Indoxylsulphuric acid. C 8 H 6 N . . S0 2 OH. The indican 

 of urine. 



A substance was long ago described as frequently occurring in the 

 urine and sometimes in the sweat of man and other animals which 

 yielded by the action of acids the blue colouring matter indigo as 

 one of the products of its decomposition. It was regarded at that 

 time as identical with the indican known to occur in several plants 

 (Indigofera tinctoria, Isatis tinctoria). Hoppe-Seyler on the other 

 hand having regard to the greater ease with which the indican of 

 plants undergoes decomposition, regarded them as most probably 

 different substances 1 . This view was confirmed by the researches 

 of Baumann who first proved that urinary indican is not a glucoside, 

 as is that of plants, but is in reality an ethereal compound of sulphuric 

 acid with indoxyl (C 8 H 6 N . OH) analogous to those already described 

 above as derived from phenol, kresol &c. 2 Indol as previously stated 

 is a characteristic product of the putrefaction of proteids. Further, 

 when administered to animals, it leads to a correspondingly increased 

 output of urinary indican 3 , an increase which is similarly observed as 

 the result of either a normally, pathologically or experimentally in- 

 creased activity of putrefactive processes in the alimentary canal 4 . 

 Hence indican is under normal conditions more plentiful in the 

 urine of herbivora than of carnivora. It is also increased in carni- 

 vorous urine under a meat diet, is not increased by the administration 

 of gelatin and is least during starvation, although in the latter case it 

 may not entirely disappear 5 . These facts correspond again to the 

 experimental observations that gelatin does not yield indol during 

 its putrefactive decomposition 6 whereas mucin does 7 , and the latter 

 substance constitutes a part at least of the contents of the alimentary 

 canal during starvation. These statements show clearly the origin 

 and mode of formation of urinary indican, the first-formed indol under- 

 going oxidation into indoxyl, which is subsequently united to the 

 elements of sulphuric acid and excreted as an ethereal compound. 



1 For earlier literature see Hoppe-Seyler's Physiol-path. Chem. Anal. Aufl. 4, 

 1875, S. 191 ; and Physiol. Chem. 1881, S. 841. 



2 Pfluger's Arch. Bd. xm. (1876), S. 301 ; Zt. f. physiol. Chem. Bd. i. (1877), 

 S. 60 ; in. (1879), S. 254. Cf. G. Hoppe-Seyler, Ibid. Bde. vn. (1883), S. 403 ; vin. 

 S. 79. 



3 Jaffe", Centralb. f. d. med. Wiss. 1872, Sn. 2, 481, 497. Virchow's Arch. Bd. 

 LXX. (1877), S. 72. 



4 Jaff6", loc. cit. Ortweiler, Mittheil. d. Wiirzburg. med. Klinik. Bd. n. (1886), 

 S. 153. Gives literature to date. 



5 Muller, Ibid. S. 341 ; Berl. klin. Wochensch. 1887, Nr. 24. (Eesults of experi- 

 ments on Cetti.) 



6 Nencki, Ber. d. d. chem. Gesell. Bd. vn. (1874), S. 1593. See also Abstr. in 

 Maly's Jahresb. 1876, S. 31. Weyl, Zt. f. physiol. Chem. Bd. i. (1877), S. 339. 



7 Walchli, Jn.f.prakt. Chem. (N. F.), Bd. xvn. (1878), S. 71. 



t. . p 

 . F.), Bd. 



