iv CONTENTS. 



PAGE. 



Denitdfication in Solutions 35 



Isolation of Denitrifiers 36 



Denitriflcation by Pure Cultures of Different Species 37 



Denitrification in Soils 38 



Conditions Favoring Denitrification in Soils : Excessive Jloisture 



and Excessive Organic JXatter 39 



Transformation of Ammonia Nitrogen into Protein 41 



Transformation of Nitrate Nitrogen into Protein 42 



Nitrogen Fixation hj Soils in Mannite Solutions. 43 



Isolation and Description of Azotobacter 44 



Nitrogen Fixation in Soils 45 



Description of Pure Cultures of Azotobacter 46 



Nitrogen Fixation by Pure Cultures of Azotobacter in Solutions 



and in Soils 47 



Influence of Different Carbohydrates on Nitrogen Fixation by 



Azotobacter 49 



Effect of Varying Reaction of the Jledium on Nitrogen Fixation 



by Azotobacter 50 



Influence of Iron ; of Phosphates and of Aeration on the Pixas 



tion of Nitrogen by Azotobacter 51 



Influence of Varying Quantities of Sugars on Nitrogen Fixation 



by Azotobacter 52 



Influence of Other Organisms on Nitrogen Fixation by Azo- 

 tobacter 53 



Anaerobic Nitrogen Fixation 54 



Isolation and Description of Clostridium Pasteurianum 55 



Isolation and Examination of B. Radicicola from Different 



Legumes 56 



Effect of Inoculation as Shown by the Growth of Legumes in 



Tubes 58 



Growth of B. Radicicola on Various Culture Media 59 



Cultivation of Amylobacter Species 60 



Butyric Fermentation 01 



Aerobic Cellulose Fermentation 62 



Cellulose Fermentation by Cultures of Denitrifiers 63 



Anaerobic Cellulose Fermentation 04 



Isolation and Description of Cellulose Ferments. 6.") 



Formation of Organic Acids 66 



Humus Formation 07 



Sulfat Reduction 68 



Preparation of INIedia 69 



>[ethods S2 



Descriptive Cliart 87 



