--I 



\ * 



r > I 



I 



J 



FIG. 3 



BACILLUS RADICICOLA. This bacillus is found in the nodules of leguminous 

 plants, only lives in symbiosis, and combines the nitrogen of the soil air to 

 form nitrogenous food material. The beaded rod form, and also the V- 

 and Y-shaped groups, are characteristic. 



FIG. 4 



AZOIOBACTER CHROOCOCCUM is found in all fertile soils and, living by itself, 

 enriches the soil in nitrogenous food material available for all classes of 

 plants. It is through its activities that soil which is rever manured can 

 maintain its fertility. The trees of all virgin forests and most wood- 

 lands depend on it exclusively for t leir nitrogenous food. It is ovoid 

 in form. 



