

NITRIFICATION. 81 



As products of putrefaction we find those given in the 

 preceding sections t 1 Albumoses, ammonia and amine, 

 leucin, tyrosin and other amido-bodies, oxyfatty acids, 

 indol, skatol, phenol ; then, sulphuretted hydrogen, mer- 

 captan, carbonic acid, hydrogen, and finally marsh-gas. 



In the decomposition of different nutrient media by 

 various fungi, the metabolic products just enumerated are 

 found, as a rule, only in part and in most variable com- 

 binations, so that putrefaction can scarcely be defined 

 more exactly by chemical aids than is possible by the 

 senses. I am, therefore, of the opinion that it is best to 

 employ the expression "putrefaction " only in the general 

 sense of the laity to indicate every foul-smelling decom- 

 position of albuminous bodies. (Compare Kuhn, A. H. 

 xiii, 40.) 



10. Nitrification. 



According to Heraeus (Z. H. i, 193), the ability to form 

 nitrite, at least in traces, from NH is widely distributed. 2 

 Most investigators, however, agree in stating that nitrite 

 production from NH 3 exclusively, or at least prepon- 

 derantly, is dependent upon an organism, possessing slight 

 morphologic characteristics, which Winogradsky, in his 

 original work, designated nitrosomonas. For more detailed 

 description see special part. 



Winogradsky has described somewhat more completely 

 the organism which forms nitrates from nitrites, and which 

 he calls " nitrobacter " (compare special part). Both 

 organisms are alike in that they grow only upon poor 

 nutrient materials — on mixtures of inorganic salts or agar 

 and mixtures of salts without peptone or sugar — and do 

 not grow on any of our ordinary nutrient media. The 

 contradictory statements of Stutzer and his pupils are 

 generally considered incorrect. Both organisms are widely 



1 The assertion is often made that the albuminous bodies are first 

 peptonized in every putrefaction, but since Bact. vulgare, B. Zenkeri, 

 and Bact. putidum are generally recognized as ' ' causes of putrefac- 

 tion," but never liquefy gelatin, it is not proper to speak of peptoni- 

 zation of albumin as being always present in putrefaction. 



2 Rullmann calls attention to the nitrite present in laboratory air, 

 which may easily cause mistakes (C. B. L. V, 212). 



6 



