THE NITRIFYING BACTERIA. 509 



ammonia, nitrous and nitric acids. In fact, the same 

 breaking down and building up, resulting ultimately 

 in nitrification, occurs in all nitrogenous matters that 

 are deposited 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 ap- 

 preciate the importance of this process to all life, ani- 

 mal as well as vegetable, upon the earth. 



These very important and interesting nitrifying 

 organisms, of which there appear to be several, have 

 been the subject of much study, and are found to 

 possess peculiarities of sufficient interest to justify a 

 brief description. For a long time all efforts to iso- 

 late them from the soils in which they were believed 

 to be present, and to cultivate them by the processes 

 commonly employed in bacteriological ^\•ork, 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 de- 

 vised. 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. C. and P. F. Frankland in Eng- 

 land, 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 work- 

 ing with either the same organism or very closely allied 

 species. 



The organism generally known as the nitro-monas of 



