INDEX 



169 



Phenolphthalein, 133 

 Phenolsulphonic acid, 138 

 Phosphate dissolving bacteria, solu- 

 tion for, 119 

 Pigment formation with Azotobacter, 



65 



Plant food without nitrogen, 72 

 roots, effect of, on number of bac- 

 teria, 29 



Plants, to grow, free of microorgan- 

 isms, 158-161 



Plate method of counting bacteria, 

 18 



Potato agar, 121 



Preserving plants, 140 



Protozoa, dilution method of count- 

 ing, 17 



Pure cultures, ammonification by, 

 46 



Pyrogallic acid for absorbing oxygen, 

 133 



RAISIN extract, 120 



Reaction of culture-media, 90, 91 



Reductase, 56 



Reduction of nitrates, 55 



to nitrites, 55 



to nitrous oxid, 58 

 of sulphates, 81 

 Root nodules, 69 

 Rules, laboratory, 14, 15 



SACCHAROSE solution, no 



Sampling soil, 16 



Seal for bottles, 140 

 for museum jars, 140 



Season, effect of, on number of bac- 

 teria, 30 



Sea- water, 126 



Seed sterilization, 155-157 



Shive's solution, 125, 126 



Silicate jelly, partially dialyzed, 104 

 undialyzed, 102, 103 



Sodium asparaginate agar, 96 



silicate, 102 

 Soil acidity, determination of, 151 



apparatus for determining cata- 

 lytic power of, 33 



catalytic power of, 32-34 



directions for drawing samples of, 

 16 



microorganisms in, 16 



pasteurized, 66 



sterilization, 157, 158 



suspension of, 38 



water, movement of, 87 

 Soil-extract agar, 94 



culture-media, no 



for protozoa, 97 



gelatin, 95 



stock solution, 95 

 Spore stain, 129 

 Spirophyllum, 86 



method for growing, 84 

 Spreading colonies, 20 

 Stains, how to use, 128 

 Starch agar, 115 



nitrate agar, 107 

 Steam pressure, 163 

 Sterilization, partial, effect of, on 



number of bacteria, 28, 29 

 Sugars, determination of, 152, 153 

 Sulphanilic reagent, 136 

 Sulphate reduction, solution for, 116, 



117 



Sulphur cycle, 81-83 

 Sulphuric acid, standard solution, 



134, i35 



TABLES, 162, 163 



Thermophilic bacteria, occurrence of, 



3i 

 Thiosulphates, oxidation of, 83 



solution for oxidation of, 118 

 Thread bacteria, solution for, 118 

 Titration of culture-media, 90, 91 



