ABSTRACTS OF REPORTS OF EUROPEAN INVESTIGATIONS. 



Recent investigations concerning the organisms of nitrification, S. Wino- 

 gradsky {An. de Vlnst. Pasteur, 4 (181)0); pp. 213, 257, 7G0, and 5 (1891) 

 p. 1)2). — The iuteresting question as to the cause of the nitrification of 

 ammonium salts in soils has recently found a definite answer in the 

 investigations of S. Winogradsky at Zurich. The nitrifying organisms 

 so often searched for seem to have been found, successfully isolated 

 and cultivated, and their characters, nitrifying action, and methods of 

 culture carefully studied. 



In connection with a report of his own work, the author reviews 

 some of the more important investigations previously made on this 

 subject. As is well known. Schlosing and Miintz* showed nitrification 

 to be due to lower forms of life and to take place only in their pres- 

 ence. They were not able, however, to isolate and cultivate these 

 organisms. 



In 1886 Heraeus t claimed to have reached positive results. He 

 secured pure cultures from soil and from old urine, which after a time 

 gave a slight reaction for nitric acid, but the nitrates formed were too 

 small to be estimated. The nitric acid in these cultures may have been 

 absorbed by the cultures from the air; and as he did not succeed in 

 isolating and proving ixwj organism to be capable of nitrification, his 

 experiments are considered inconclusive. 



A. B. Frank f isolated several forms of bacteria from soil, but as 

 none of them produced nitrification he was inclined to believe that 

 nitrification was not due to the action of organisms. 



Oelli and Marino Zucco § isolated five forms of bacteria from a water 

 rich in nitric acid and tested their nitrifying action. The cultures 

 showed a reaction for nitric acid with diphenylamin after several days, 

 but the control cultures which had not been inoculated also showed 

 this reaction, though somewhat weaker. Adametz || investigated two 

 samples of soil, and after several weeks' time secured only traces of 

 nitrates in his cultures. 



In 1887 Frank ^ attempted to explain the phenomena of nitrification 



* Compt. rend. 84, 85, 86, 89. 



t Zeitsch. f. Hygiene 71, 193, 



tBer. d. d. bot. Ges.,1886. 



$ Rendiconti della R. Accademia dei Lincei, 188G. 



II Inauirnral Dissertation, Leipzig, 188G. 



ULaudw. Jahrb., 1887. 



751 



