viii A MANUAL OF BACTERIOLOGY 



SECTION XI. BACTERIA OF WATER AND SEWAGE 



73. COLLECTING SAMPLES OF WATER 51 



74. QUANTITATIVE STUDY OF BACTERIA IN SURFACE WATERS . 52 



75. QUALITATIVE STUDY OF BACTERIA IN SURFACE WATERS . 53 



76. PRESUMPTIVE TEST FOR BACILLUS COLI 54 



77. TESTS FOR FECAL BACTERIA 54 



78. QUANTITATIVE EXAMINATION OF SEWAGE 55 



79. BACTERIAL CONTENT OF SNOW AND OF RAIN WATER . . . 55 



80. STUDY OF STREPTOCOCCI 55 



81. ISOLATION OF BACILLUS COLI 56 



82. STUDY OF CHARACTERS OF BACILLUS COLI 57 



83. STUDY OF BACILLUS PROTEUS VULGARIS 57 



84. STUDY OF AEROBIC ORGANISMS WHICH DECOMPOSE CELLULOSE 58 



85. STUDY OF ANAEROBIC ORGANISMS WHICH DECOMPOSE CELLULOSE 58 



86. CELLULOSE DECOMPOSITION WITH FORMATION OF HYDROGEN 59 



SECTION XII. BACTERIA OF THE SOIL 



87. OBTAINING SOIL SAMPLES ' .... 60 



88. PREPARING DILUTIONS AND POURING PLATES 61 



89. DETERMINATION OF THE NUMBER OF SPORES IN SOIL ... 61 



90. AMMONIFICATION OF PEPTONE BY SOIL BACTERIA .... 62 



91. AMMONIFICATION OF NITROGENOUS SUBSTANCES IN SOIL . . 63 



92. NITRITE FORMATION IN SOLUTION 64 



93. NITRATE FORMATION IN SOLUTION 64 



94. NITRIFICATION IN SOIL 65 



95. REDUCTION OF NITRATES BY BACTERIA 66 



96. THE REDUCING ACTION OF DENITRIFYING BACTERIA UPON 



NITRATES AND METHYLENE BLUE 66 



97. NONSYMBIOTIC BACTERIA WHICH FlX ATMOSPHERIC XlTROGEN. 



ISOLATION AND STUDY OF AZOTOBACTER 67 



98. GROWTH OF AZOTOBACTER IN PURE CULTURES 67 



99. SYMBIOTIC BACTERIA WHICH Fix ATMOSPHERIC NITROGEN. 



BACILLUS RADICICOLA 68 



100. ISOLATION AND CULTURE OF BACILLUS RADICICOLA .... 70 



101. THE PRODUCTION OF BACTEROIDS OF BACILLUS RADICICOLA 



UPON ARTIFICIAL MEDIA 70 



102. THE FORMATION OF TUBERCLES UPON ROOTS OF LEGUMES . 71 



103. THE REDUCTION OF SULPHATES BY BACTERIA 71 



104. THE CULTIVATION OF BACILLUS AMYLOBACTER 72 



105. STUDY OF BACILLUS MYCOTDKS . 72 



