154 AGRICULTURAL BACTERIOLOGY. 



There has been, in the last few years, an attempt made by 

 bacteriologists to meet the difficulty here arising, by furnishing 

 to the agriculturist a culture of the tubercle bacteria for the 

 purpose of inoculating his soil, and thus providing it with the 

 proper organisms to produce the tubercles. Such a material 

 has now been on the market and under experimental tests for 

 several years under the name of Nitragin. This commercial 

 product is found by analysis to consist of a practically pure 

 culture of certain of these tubercle bacteria, which are capable, 

 when inoculated into sterilized soil, of producing the tubercles 

 upon the roots of the leguminous plants. Although the 

 method of manufacture is not known, there is little doubt that 

 the material comes directly from the tubercles of certain legu- 

 minous plants, and that the bacteria thus obtained have been 

 produced in large amount in the bacteriological laboratory and 

 eventually furnished, as a commercial product, in the form of a 

 practically pure culture. 



The use of such a product evidently may or may not be of 

 value to the agriculturist, according to conditions. If it is 

 true that different species of legumes require at least different 

 physiological varieties of bacteria to enable them to produce 

 their proper tubercles, it will follow clearly that a product like 

 Nitragin, containing a pure culture of one variety, could not be 

 appropriate to all species of legumes. It might be advanta- 

 geous with some crops but not with others. Further, if it is 

 true that ordinaiy soil contains the tubercle bacteria in suffi- 

 cient quantity for the production of the tubercles upon leg- 

 umes, no advantage could, of course, be expected from adding 

 to that soil similar bacteria in the form of a pure culture like 

 Nitragin. 



These are not simply theoretical conclusions ; they are con- 

 clusions which have been deduced from experiments with 

 Nitragin, carried on now in large numbers in many localities 

 for some years. The results of the use of this material have 



