CONTENTS 



PAGE 



Introduction 9 



Scope of the investigation ; 9 



Method of investigation 10 



Organism 10 



Media 10 



Sterihzation of utensils 10 



Sterilization of seed 10 



Sterilization of media and soil 12 



Method of growing the plants 12 



Inoculations 13 



Examination of plants for nodules 13 



Special method for growing plants under sterile conditions . . 13 



Part I. Isolation and identification of the organism 14 



Isolation of Bacillus radicicola 14 



Identification of the organism 15 



Morphology of the organism 16 



Cultural and biochemical features 18 



Part II. Influence of certain factors on nodule production 19 



Experiment 1. Influence of aeration in light and in darkness. ... 21 

 Experiment 2. Influence of some nutrient solutions in light and 



in darkness 22 



Experiment 3. Influence of potassium nitrate in fight and in 



darkness 24 



Experiment 4. Influence of potassium nitrate and calcium nitrate 



in Pfeffer's solution 25 



Experiment 5. Influence of various concentrations of Pfeffer's 



solution, both with and without nitrates 26 



Experiment 6. Influence of Pfeffer's solution in which the essen- 

 tial elements were absent 26 



Experiment 7. Influence of moisture 27 



Experiment 8. Influence of certain substances in varying 



quantities 27 



Experiment 9. Influence of certain additional substances 29 



General discussion of results of experiments 32 



5 



