FIXATION OF ATMOSPHERIC NITROGEN. 283 



more satisfactory results. The dry cotton cultures were exploited for a 

 time by a commercial firm under the name of Nitro-culture, and some- 

 what similar cultures were placed on the market in England under the 

 name of Nitro-bacterine. Cultures of both kinds, however, have been 

 shown to be valueless, both by microbiological and by planting tests. 



Cultures on A gar. The most promising results thus far in the use of 

 pure cultures appear to have been secured at the Ontario Experimental 

 Farm, where Harrison originated the method of growing the bacteria upon 

 a nitrogen-poor agar medium. By this method the farmer has simply to 

 apply the bacteria to the seed just before sowing. These cultures as 

 used on all the common legumes, sown in all kinds of soil, have given 

 favorable results in about 65 per cent of trials. Similar agar cultures 

 are now prepared by commercial firms who have adopted Harrison's 

 method and also by some of the U. S. Agricultural Experiment Stations. 

 Liquid cultures of Nitragin are also sold in Europe and America. 



Alinit. Alinit was the trade name applied to cultures placed on the 

 market in 1897, of B. ellenbachensis, isolated by Caron, owner of the 

 Ellenbach estate in Germany, and claimed by him to be one of the non- 

 symbiotic nitrogen-fixing bacteria. Alinit was examined and tested by 

 numerous investigators and the organism was found to be incapable of 

 nitrogen-fixation . 



Azotobacter Cultures. A great deal of experimental work is being 

 conducted at the present time in the use of artificial cultures of the azo- 

 tobacter species. The results thus far, however, are contradictory, and 

 much more work needs to be done to prove the efficiency of such cultures. 



The lack of complete success thus far with artificial cultures for soil 

 inoculation does not afford sufficient ground for condemnation of the 

 method. Failure may often be attributed to unsuitable soil conditions 

 rather than any inherent failing in the culture used, and no method of 

 inoculation will compensate for poor physical or chemical condition of the 

 soil itself. The principle of using artificial cultures to be applied with 

 the seed is sound, and if the cultures contain large numbers of living 

 bacteria, there is little reason why they should not prove of benefit when 

 used under soil conditions that would seem to warrant their need. 



