I 4 THE SIMPLER NATURAL BASES 



Putrescine and Cadaverine, C 4 H ia N 2 and C 5 H U N 2 . 



These two homologous diamines have similar properties and 

 generally accompany each other, so that they may be most conveniently 

 considered together. They were discovered by Brieger [1885, 1, 2] by 

 his new method of investigating putrefaction bases ; cadaverine was 

 soon afterwards shown by Ladenburg [1886] to be identical with 

 the pentamethylene-diamine previously obtained by reduction of tri- 

 methylene dicyanide, and later Udranszky and Baumann [1888, 2] 

 proved the identity of putrescine with tetramethylene-diamine. 



Putrescine and cadaverine are among the commonest of all putre- 

 faction bases. They probably escaped the notice of earlier investigators 

 on account of their sparing solubility in ether and in chloroform, but 

 Brieger obtained them repeatedly from various sources and they have 

 been isolated many times since. The possibility of the formation of 

 cadaverine from lysine by loss of CO 2 was already considered by 

 Udranszky and Baumann and the origin of both amines was definitely 

 established by Ellinger [1900] who obtained putrescine by the 

 action of putrefactive bacteria on ornithine : 



NH, . CH 2 . CH 2 . CH 2 . CH(NH 2 ) . COOH = NH a . CH a . CH a . CH a . CH a . NH a + CO a ; 

 and similarly cadaverine from lysine : 



NH a . CH 2 . CH a . CH a . CH 3 . CH(NH 2 ) . COOH = 



NH 2 . CH 2 . CH 2 . CH 2 . CH a . CH 2 . NH a + CO 2 . 



These important results furnished the first examples of the bacterial 

 decarboxyjation of amino-acids. With access of air Ellinger ob- 

 tained a. 12 per cent, yield of putrescine and under anaerobic conditions 

 a 50-60 per cent, yield (three days at 37) ; with cadaverine the yield 

 was 36 percent. Ackermann [1909, I], who more recently repeated 

 Ellinger's experiments, was at first unable to obtain putrescine and 

 cadaverine from the pure amino-acids but succeeded in the case of 

 the products of the hydrolysis of caseinogen by acids. He showed 

 that putrescine but not cadaverine is formed in the putrefaction of 

 gliadin [1909, 2], which does not contain lysine, and ultimately he 

 [1910, 3] found that the addition of 0*25 per cent. Witte peptone and 

 O'5 per cent, glucose to the culture medium greatly facilitated decar- 

 boxylation. In the earlier experiments only traces of inorganic salts 

 had been added. When once formed, cadaverine and putrescine are 

 apparently very resistant to the action of micro-organisms, for Brieger 

 and others isolated the bases in considerable quantity after putrefac- 

 tion had been going on for months. 



Apart from such bacterial formation of putrescine and cadaverine, 



