CELLULOSE AS A SOLTECE OF ENERGY FOR NITROGEN FIXATION. 33 



The table shows that the sohitions contammg Azotohacter chroo- 

 coccum and Bacillus rossica fixed 8.44 milhgrams of nitrogen on the 

 average for each 500 cubic centimeters of sohition, while the average 

 quantity fixed by A. heijerinchii and B. rossica was but httle higher. 

 The 1 gram of filter paper added to these solutions was almost com- 

 pletely destroyed, so that the gains secured are for approximately 

 1 gram of cellulose. 



The solutions inoculated with Bacterium Jimi as the cellulose- 

 destroying organism show gains somewhat higher than those secured 

 from the solution containing Bacillus rossica as the cellulose destroyer, 

 although much more of the cellulose remained undissolved in the 

 solutions containing Bacterium Jimi. It would therefore appear that 

 the products formed by Bacterium Jimi may be of greater value in 

 stimulating the nitrogen-fixing properties of Azotobacter than those 

 formed by Bacillus rossica. 



The nitrogen gains in the solution containing Bacterium Jlavigena 

 and Azotohacter chroococcum or A. heijerinclcii are also higher than 

 the gains secured in the Bacillus rossica series and but little lower 

 than the gains in the Bacterium Jimi series. Only a part of the cellu- 

 lose added was dissolved, so that the gains can not be estimated for 

 each gram of cellulose consumed. 



CONCLUSIONS. 



The addition of 0.1 per cent of ammonium sulphate to the nutrient 

 solution stimulated the nitrogen-fixing power of Azotobacter chroo- 

 coccum and A. heijerinclcii. 



Mixed cultures of Bacillus rossica and Azotohacter chroococcum in 

 solutions containing both dextrose and cellulose as sources of energy 

 gave decided gains over Azotobacter alone only when the solutions 

 contained a considerable quantity of initial nitrogen and a destruction 

 of the cellulose occurred. 



Azotohacter cJiroococcum and A. heijerinclcii in association with 

 Bacillus rossica, Bacterium. Jimi, or Bacterium fiavigena fixed quantities 

 of nitrogen varying from 7.72 to 11.41 milligrams for each 500 cubic 

 centimeters of solution containing cellulose only as a source of energy. 



£Cir. 131] 



