244 LECTURE XI. 



the conversion of nitrobenz aldehyde into nitrobenzoic acid, and the sub- 

 sequent formation of nitrohippuric acid: 1 



NO 2 . C 6 H 4 . CHO + = NO 2 . C 6 H 4 . COOH 

 Nitrobenzaldehyde Nitrobenzoic acid 



N0 2 .C 6 H 4 .COOH + NH 2 .CH 2 .COOH = NO2.C 6 H 4 .CO.NH.CH2.COOH 



Nitrobenzoic acid Glycocoll Nitrohippuric acid 



+ H 2 



The conversion of benzamide 2 into hippuric acid is especially note- 

 worthy on account of the fact that water must be added to form benzoic 



aCld: C 6 H 4 .CONH 2 + H 2 = C 6 H 4 .COOH + NH 3 



Benzamide Benzoic acid 



The ability of the organism to unite other substances with glycocoll 

 is not confined to benzoic acid or its derivatives, but the same is true of 

 the carboxylic acids of furan-, thiophen- and pyridine-nuclei. Thus, from 

 thiophenaldehyde 3 thiophenic acid is formed, which in the presence of 

 glycocoll goes over into thiophenuric acid: 



C 4 H 3 S . CHO + O = C 4 H 3 S.COOH 



Thiophenaldehyde Thiophenic acid 



C 4 H 3 S.COOH + NH 2 .CH 2 .COOH = C 4 H 3 S.CO.NH.CH 2 .COOH + H 2 O 



Thiophenuric acid 



Such reactions in the animal organism are of interest in more than one 

 way. Such investigations give an idea of the activity of the animal cell. 

 We notice that oxidation and reduction processes are carried out with the 

 greatest ease, while water is split off, or added, as the case demands. 



We ask ourselves, Where does the animal organism obtain the glycocoll 

 which enters into these combinations? We have seen that this amino 

 acid is found among the many cleavage-products of the albumins. There 

 can be no doubt that the animal cells obtain the necessary glycocoll 

 by the decomposition of proteins. The fact that glycocoll will unite with 

 benzoic acid and analogous compounds under technical conditions, per- 

 mits us to draw valuable conclusions regarding the decomposition of 

 albumins in the tissues. There is little doubt that this also applies to 

 the amino acids. The glycocoll formed is usually further disintegrated 

 into urea; if, however, benzoic acid happens to be present in the tissues, 

 the glycocoll, produced as an intermediate substance, is removed from 

 further metabolism. We have already seen that other albumin cleavage- 



1 Ibid. 17, 274 and 292 (1893). 



3 L. v. Nencki: Arch. exp. Path. Pharm. 1, 420 (1873). 



3 R. Cohn: Z. physiol. Chem. 17, 281 (1893). Cf. E. Fromm: Die chemischen 

 Schutzmittel d. Tierkorpers bei Vergiftungen, K. J. Triibner, Strassburg, 1903, p. 14; 

 also M. Nencki: Opera omnia (Vieweg and Sohn, Braunschweig, 1905). 



