618 THE FIXATION OF NITROGEN BY AZOTOBACTER CHROOCOCCUM. 



made to find out to which of the components of the mixed culture 

 the fixation was due. 



The Yield of Slime and Gain of Nitrogen by the Bacteria alone and in 



Combination. 





Twice infected. 



Once infected. 





Slime, 

 grms. 



Nitrogen 

 gained, 

 mgrms. 



Slime, 



grms. 



Nitrogen 

 gained, 

 mgrms. 





3 



6 







13 



S 

 7 



I 16 





 



1 

 

 2 

 3 

 3 



4* 



It 





 12 



7 



12 

 15 

 16 





Azotobacter chroococcum 



B. levant for mans 



B. radiobacter + Azotobacter.. 

 B.radiobacter + levaniformans 

 Azotobacter + levaniformans.. 

 B. radiobacter + Azotobacter 



2 

 

 3 

 

 3 

 3 

 3 







The experiment bears out Beijerinck and v. Delden's results, 

 that the fixation of nitrogen by these bacteria is chiefly, if not 

 entirely, due to Azotobacter chroococcum; and when considered with 

 the first experiment, it indicates that the combination of bacteria 

 brings about a quicker and more regular fixation. 



A coccus had accidentally gained access to the plate, 

 t The slime had been autodigested. 



