The Fixation of Nitrogen 



131 



THE FIXATION OF NITROGEN BY MEANS OF BACILLUS 

 RADICICOLA WITHOUT THE PRESENCE OF A 

 LEGUME. 

 By Edwin B. Fred and W. B. Ellet. 



While it is known that Bacillus radicicola will live and 

 assimilate nitrogen with the presence of the appropriate host 

 plant, the question naturally arises as to the action of these 

 organisms in the soil without any legume. The fact that 

 Bacillus radicicola will live on artificial media and will assimi- 

 late very small amounts of nitrogen without the presence of 

 its host plant has been demonstrated several times. * 



In order to study the activities of Bacillus radicicola with- 

 out the presence of a legume, a series of laboratory and green- 

 house experiments was planned. (1) The nitrogen assimilating 

 power of Bacillus radicicola in a nitrogen-free liquid medium 

 using pure and mixed cultures. (2) Its assimilating power in 

 sterilized sand as shown by analysis for total nitrogen and by 

 plant growth. (3) Its assimilating power in a normal clay soil 

 tested in the same way as the sterilized sand. 



As the amount of nitrogen fixed is very small the reagents 

 used must be absolutely pure and the analyses done in the most 

 accurate manner. As a liquid medium the following formula 

 Was used : . . 



gM (Water (dist.) 1000 c. c. 



-j/ (diphosphate of potash 1 gr. 



^1/ ^a-gnesium sulphate 0.1 gr. 



.gll <%pqtrose 20 gr. 



,gM (^P^i um chloride trace. 



.sM (^(59(13/ sul]>hate trace. 



I r^^Wganese sulphate trace. 



Calcium chloride. ., trace. 



iinaja^o o^arTj fern viies , . 



Two hundred and fitty c. c. oi this medium were placed m 



large ^rlenn^ever flasks so as to expose as much of the surface 

 -iisu'drts -iiiiu. fell t nwoife .«•« 



of the hauid to the air as possible, and the llasks were mocu- 



laiect with pure 1 an d" mixed cultures from fifteen of the legumes, 

 atf] m .ferlf J^rarlj ol , L . f ._ A , . 



the pure cultures were obtained lrom different sources ana, in 



several cases^ tne organisms were found not to be true to name. 



Trusts especially true in the first two of each series of the sand 

 -noo zyiunuD gujq io Z3tm 



*1. A. Stutzer, Mitteil Landwirtsch. Inst. Breslau, Heft 3 (1900). 



2. L. Hiltner. Centr. Bakt. Bd. VI. p. 273 (1900) (II Abt.) 



3. E. Laurent, compt. rend . Tome CXI, p. 754 (1890); Ann. Inst. Pasteur Tome VI 

 Jc3ii;jTjxiJ22 Trorie VI. p. 105 M891).- 



4. Maze, Ann. Inst. Pasteur. Tome XI, p. 44 (1879). 



