H. P». Hutchinson and J. Clayton 171 



Table XIll. 



Associative Growth of Nitrogen-fixing iind 

 Cellulose-decomposing Organisms. 



Mean total N after 4 weeks 



Azotobacter and 

 Azotobacter crude culture of 



Control alone cellulose organism 



Set A (mannite) 0-735 mgrms. 0-91 mgrms. 2-835 mgrms. 



Set B (sod. nitrate) 7-17 „ U-44 „ 4-69 



The presence of 0-05 grm. of mannite failed to give any increase of 

 nitrogen over the control, but the addition of 1-0 grm. of cellulose 

 together with cellulose-decomposing organisms gave what may be 

 regarded as a definite increase. 



A similar experiment was also carried out, but in this case the solution 

 contained 1-0 per cent, mannite; 50 c.c. solution and 1-0 grm. cellulose 

 were again taken for each flask. The results are: 



Total nitrogen in flasks after 3 weeks 



The results thus show a fixation of 4-27 mgrms. nitrogen per gram of 

 mannite, and a supplementary fixation of 3-01 mgrms. when cellulose 

 was also supplied. 



In a third experiment the amount of cellulose lost during the 

 fermentation was ascertained prior to the determination of total nitrogen. 

 The mean nitrogen content of the respective flasks was found to be 

 1-19, 1-1%, and 5-74 mgrms. : the loss of cellulose during fermentation 

 amounted to 0-153 grm. From these data it may be calculated that the 

 fixation of nitrogen per gram of mannite swp^feti was equal to 3- 18 mgrms., 

 while that per gram of cellulose nctnnWij decomposed was no less than 

 19-3 mgrms. All three experiments provide definite indications of the 

 value of cellulose breakdown products for the assimilation of atmo- 

 spheric nitrogen. Somewhat analogous results have also been obtained 

 by the combined growth of anaerobic cellulose-decomposing and 

 anaerobic nitrogen-fixing bacteria^. 



' Pringsheim, H., Cetif. Bakt. Pur. ii, 1909, 23. 300-304: 1910, 26. 222-227. 



