CHAP, in The absorption of Nitrogen 347 



Prazmowski, in 1888, confirmed Ward's account of the 

 structure of the organism, but pronounced it to be a 

 Schizomycete which possesses a filamentous zoogloea. He 

 says that only part of the bacteria become transformed 

 into the bacteroids and that these dissolve to furnish food 

 to the host. 



The organism was isolated from the tubercles in 1888 by 

 Beijerinck, who was able to infect plants of Vicia faba 

 from his cultures. He gave it the name Bacillus radicicola ; 

 he thought it a single organism, manifesting, however, 

 special characters in different cases, their determining 

 factor being the influence of the particular host plant. 



In 1890 Frank published the results of an investigation 

 in the course of which he advanced totally different views. 

 He said the bacteroids are formed by the plant itself 

 through the breaking up of a network of living substance 

 consisting of an intimate mixture of fungal and plant 

 protoplasm, which he called mycoplasm. The bacteroids 

 contain cocci which are the real germs. Frank renamed 

 the organism Rhizobium leguminosarum. 



In 1889 Vines showed that poverty of a soil in nitrates 

 acts as a stimulus to the formation of the tubercles. 



Passing over a number of papers which were generally 

 confirmatory of some or other of the results just detailed, 

 we come to certain researches by Maze and by Nobbe and 

 Hiltner, which throw a little light on the position of the 

 organism in the process. In 1897 Maze found that cultures 

 of it, made quite apart from the leguminous plant, can 

 bring atmospheric nitrogen into combination. The cultures 

 were made in solutions of protein and showed a great 

 gain in the nitrogenous content of the liquid after the 

 culture had been well established. 



In 1899 Nobbe and Hiltner proved that the nitrogen is 

 appropriated by the organism and is not fixed by the 

 leaves of the leguminous plant. This fact had not before 



