8 THE SIMPLER NATURAL BASES 



or the carboxyl-group may be eliminated as formic acid, in which case 

 reduction must take place : 



R R 



CHNH a + H = CH., . NH a + H . COOH. 



j COOH H | 



Neubauer [1911] considers that decarboxylation generally takes 

 place in both these ways, since carbon dioxide and formic acid are 

 among the regular products of putrefaction. In either case a primary 

 amine results. 



The same process, applied to dibasic monamino-acids, results in 

 the formation of &>-amino-acids, which are feebly basic putrefaction 

 products and are described in the next chapter. &>-Amino-acids are also 

 formed by the deaminization of diamino-acids ; the deaminization of 

 monamino-acid yields non-nitrogenous acids such as isocaproic (from 

 leucine) and succinic (from aspartic acid). Deaminization is accom- 

 panied by reduction, since hydroxy-acids and unsaturated acids ap- 

 parently do not occur in putrefaction : 

 R R 



CHNH 2 + 2H = CH 2 + NH 3 . 

 COOH COOH 



By a combination of the two processes of decarboxylation and 

 deaminization, methane may be formed from glycine and -butyric 

 acid from glutamic acid (Neuberg and Rosenberg [1907]). A putre- 

 factive process involving only reduction is the conversion of proline into 

 S-aminovaleric acid. 



The importance of reduction in the above bacterial actions is ex- 

 pressed by the fact that they chiefly take place under anaerobic con- 

 ditions. Bienstock [1899, 1901], one of the chief workers in this field 

 on the bacteriological side, concludes that putrefaction, in the ordinary 

 sense, cannot take place without an obligate anaerobe, such as Bacillus 

 putrificus. B. coli hinders the action of B. putrificus and B. tetani has 

 no action on fibrin. Rettger [1906, 1907 ; Rettger and Newell, 1912] 

 shares the view that putrefaction is the work of strict anaerobes. 



The access of oxygen induces further changes ; p-hydroxy-phenyl- 

 propionic acid (formed by the deaminization of tyrosine) is oxidised, 

 according to Baumann and Nencki, to p-hydroxy-phenyl-acetic acid, 

 which is successively converted into p-cresol and phenol, and simi- 

 larly indole-propionic acid (from tryptophane) yields indole-acetic acid, 

 skatole, and indole. Oxidation also accounts for the shortening of 



