54 



biosis with other bacteria, and that nitrites were not reduced 

 to free nitrogen except in harmony with organisms which re- 

 duced nitrates to nitrites. He discovered that the following 

 organisms, in cooperation with Bacillus praepollens, would 

 effect this reduction: "B. acidi lactici, B. capsulatus, B. cre- 

 moides, B. cuniculicida mobilis, B. diphtheria columbarum, 

 B. enteritidis Gartneri, B. from lean meat, B. indigonaceus, 

 B. mycoides, B. mesentericus ruber, B. mesentericus Flugge 

 I, III and VII, B. mustelae septicus, B. miniaceus, B. pro- 

 digiosus, B. pneumoniae, B. proteus mirabilis, B. proteus 

 vulgaris, B. psitticosis, B. rhinoscleromatis, B. ruber of Kiel, 

 B. ruber plymouth, B. ruber purpureus, B. suipestifer, B. 

 Hog-cholera (Salmon), B. swine plague, B. typhi-abdominalis, 

 B. typhi-murium, B. violaceus, B. coli commune I, II, III, IV, 

 B. lactis aerogenes, B. phosphorescens, M. candicans, Staph- 

 lococcus pyogenes albus, Staphlococcus pyogenes aureus, 

 Sarcina flava II, Vibrio Blankenese, Vibrio Mottlau II, Vibrio 

 tyrogenes Deneke." 



An attempt was made to isolate the organisms from the 

 soil, which perform the function of reducing nitrates to free 

 nitrogen. As far as possible all the organisms were isolated 

 from soil number 9. None of these bacteria reduced nitrates 

 to free nitrogen in pure culture. Of the fifteen different species 

 thus isolated various combinations were made in the hope of 

 discovering a symbiotic relation, but of the many combina- 

 tions thus effected in no instance did I succeed in securing the 

 desired result. After fishing the different colonies from a 

 great number of plates, the agar in several was carefully rolled 

 together with a sterile spatula and introduced into a medium 

 prepared for the reduction of nitrates, those plates which con- 

 tained the greater number of colonies invariably reduced the 

 nitrate to free nitrogen, but in some of the plates on which 

 were few colonies no reduction took place. 



I am under obligations to Dr. A. F. MacLeod, Assistant 

 Professor of Physical Chemistry in Beloit College, Beloit, 

 Wisconsin, for valuable suggestions and assistance; and like- 

 wise to Dr. H. H. Waite, Professor of Bacteriology and Patho- 

 logy in the University of Nebraska, for valuable suggestions 

 and assistance. 



