CONDITIONS AFFECTING LEGUME INOCULATION. 83 



mine all of the conditions incident to success or failure in legume 

 inoculation. « It is safe to assume, however, that the action of a bac- 

 terium in the soil is conditioned not only by the chemical and physical 

 characteristics of the soil solution at a particular time, but also, and 

 perhaps essentially^, by the biologic conditions obtaining in that soil. 



SUMMARY. 



1. Lime is of decided benetit in obtaining successful inoculations 

 of legumes in some soils. These soils often show an acid reaction to 

 litmus. 



2. Soil extracts serving as culture media often indicate the probable 

 success of inoculating a leguminous crop. This, however, may not 

 always hold true. 



3. At least during the first season's growth no general cross- 

 inoculation takes place. Bacteria from one host may, however, inocu- 

 late a physiologically related species. 



4. Heavy inoculation by a pure culture increases nodule formation 

 if the soil solution is enriched by the excess of culture medium; how- 

 ever, in a favorable soil a light inoculation Avell distributed is as 

 effective. 



5. Thorough aeration is favorable to nodule formation. 



6. Whether in a synthetic medium or a natural soil solution, the 

 functions of a bacterium are influenced by the associative or competi- 

 tive action of the various groups of organisms with which it comes in 

 contact, as well as by the nature of the culture material. 



«See Maria Dawson, Phil. Trans. Roy. Soc. London, Ser. B, vol. 193 (1900), p. 65. 

 100— viir 



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