132 



The Plant World 



cultures. The mixed cultures were prepared in laboratory by 

 washing nodules repeatedly in sterile water, then in a solution 

 of 1 to 1000 of mercuric chloride, rinsing in sterile water and 

 drying between folds of filter paper. After the nodule has been 

 treated thus, it is cut open with a sterile knife and from the cen- 

 ter of the nodule the medium is transferred with an inoculating 

 needle in the ordinary manner. Cultures prepared in this way 

 contain, besides Bacillus radicicola, sl few yeasts and moulds. 

 After inoculation, the flasks were then placed in an incubator 

 and kept at 25 degrees C. for one month. Table No. I shows 

 the results from inoculation of liquid media. 



TABLE I. 



Assimilation of Nitrogen by Means of Bacillus radicicola in Liquid Media 



for Four Weeks. 



Nitrogen in 1000 c.c. 



No. Culture. of liquid media. 



1 . . . Alfalfa, Pure Culture 7.00 Mg. 



2 . . . .Alfalfa, Pure Culture 11.20 Mg. 



3 . . . . Alfalfa, Pure Culture . 16.80 Mg 



4 . . . . Alfalfa, Mixed Culture 12.60 Mg. 



5 . . . .Red Clover, Pure Culture * 5.60 Mg. 



6 . . . .Red Clover, Mixed Culture 11.20 Mg 



7 . . . .Crimson Clover, Pure Culture * 1.80 Mg. 



8 . . . .Crimson Clover, Mixed Culture 14.00 Mg 



9 . . . . White Clover, Pure Culture 14.00 Mg. 



10 . . . Alsike Clover, Pure Culture * 5.60 Mg 



11 . . .Lupine, Pure Culture 11.20 Mg. 



12 . .Vetch, Pure Culture * 7.00 Mg. 



13 . . .Vetch, Mixed Culture 14.00 Mg. 



14. . .Cowpea, Pure Culture 8.40 Mg. 



15 . . . .Cowpea, Mixed Culture 14.00 Mg. 



16 . . .Check 00.00 Mg. 



The results of this table show very clearly that these bacteria 

 have power to assimilate nitrogen from the atmosphere in arti- 

 ficial media. Recent researches * have shown that this assimi- 

 lation is greater in flasks with large bottoms than in flasks small 

 at the bottom. This is due, of course, to the fact that, in the 

 large-bottom flasks more surface is exposed to the air. The pure 

 cultures did not assimilate, on the average, as much nitrogen as 

 the mixed cultures. Only one of the series of pure cultures con- 



* Organisms grown in these cultures were not true to name. 



*A Study of the Legume Organisms, T. B. Hutcheson and E. B. Fred, V. P. I. Agr. Journal 

 June, 1908. 



