SOIL MICROORGANISMS AND LEGUME BACTERIA 313 



tomatin of tomato plants, serve to protect the plant against invasion by 

 fungi and other pathogens still remains to be determined (456a). 



SOIL MICROORGANISMS IN RELATION TO 

 LEGUME BACTERIA 



The possible injury caused to leguminous plants by the antagonistic 

 action of soil bacteria upon the root nodule bacteria has been but little 

 investigated (524). Certain bacteria belonging to the Pseudomonas and 

 Achromobacter groups exercise a strong influence upon the nodule bac- 

 teria in the root zone or rhizosphere of the legumes. Some stimulate, 

 others depress, and still others have no effect at all upon the growth of 

 the legume bacteria. The stimulating effect of non-nodule bacteria upon 

 the nodule bacteria often is very striking {_SZli)' 



