372 BACTERIOLOGY. 



resulting ultimately in nitrification, occurs in all nitro- 

 genous matters that are thrown upon the soil and 

 allowed to decay. It is largely through this means that 

 growing vegetation obtains the nitrogen necessary for 

 the nutrition of its tissues, and when viewed from this 

 standpoint we appreciate the importance of this process 

 to all life, animal as well as vegetable, upon the earth. 



These very important and interesting nitrifying 

 organisms, of which there appear to be several, have 

 been subjected to considerable study and are found to 

 possess peculiarities of sufficient interest to justify a 

 more or less detailed description. For a long time all 

 effiarts to isolate them from the soils in which they were 

 believed to be present, and to cultivate them by the 

 processes commonly employed in bacteriological work, 

 resulted in failure, and it was not until it was found 

 that the ordinary methods of bacteriological research 

 were in no way applicable to the study of these bacteria 

 that other, and ultimately successful, methods were 

 devised. By these special devices nitrifying bacteria, 

 capable of oxidizing ammonia to nitric acid, have been 

 isolated and cultivated, and the more important of their 

 biological peculiarities recorded by Winogradsky in 

 Switzerland, by G. and P. F. Frankland in England, 

 and by Jordan and Richards in this country. From 

 the similarity of the properties, given by these several 

 observers, of the nitrifying organisms isolated by 

 them, it seems likely that they have all been working 

 with either the same organism or very closely allied 

 species. 



The organism generally known as the nitro-monas 

 of Winogradsky is a short, oval, and frequently almost 

 spherical cell. It divides as usual for bacteria, but 



