i68 



INDEX 



Isolation of nitrifying bacteria, 50 

 of ureal ermenting organisms, 36,37 



Iterson's solution for cellulose fer- 

 mentation, 112 



Labeling slides, 1 29 

 Laboratory rules, 14, 15 

 Lactic acid for casein agar plates, 21 

 Lactose, effect of, on growth of Azoto- 



bacter, 65 

 Legumes, artificial cultures for the 



inoculation of, 73 

 Lieske's solution, 108 

 Limestone, effect of, on number of 



bacteria, 27, 28 

 Literature, 12, 13 

 Lofller's methylene-blue, 127 



Maltose solution, no 



Mannit, effect of, on growth of Azoto- 

 bacter, 65 

 for nitrogen fixation, 63 

 solution, 108 



Manure, effect of, on number of bac- 

 teria, 25, 26 



Meissner's solution, 128 



Mercuric chlorid, 140 



Methods, 127-163 



Methylene-blue for reduction, 56 



Methyl-orange, 133 



Methyl-red, 134 



Metric units, 162, 163 



Microorganisms in soil, 16 

 relation of, to physical properties 

 of soil, 87 



Millon's reagent, 139 



Moisture, determination of, 141 

 effect of, on number of bacteria, 

 24, 25 



Nessler's reagent, 135 

 Neutralisation of culture-media, 90, 



91 



Nitrate bouillon, io6 

 formation, 47-49 

 reducing bacteria, 55 



colonies on starch agar, 55 

 reduction by pure cultures, 57, 58 



solution for, 106 

 solution, loi 

 Nitrates, determination of, colori- 

 metric, 143 

 reduction, 144 

 Nitrification of ammonium sulphate, 

 casein, 51 

 effect of limestone on, 54 

 of moisture on, 53 

 of soil type on, 52 

 in solution, 47-50 

 Nitrifying bacteria, isolation of, 50 

 Nitrite formation, 47 



and nitrate solution, loi 

 solution for, 100 

 Nitrogen content of bacteria, 74 

 cycle, 35-74 



determination of, total, with ni- 

 trates, 147, 148 

 without nitrates, 145-147 

 fixation, anaerobic (Clostridia), 66 

 by Bacillus radicicola, 72 

 by pure cultures, 64 

 in soil, 62 

 in solution, 61 

 Nodules, formation of, 69 

 Number of bacteria in artificial 



legume cultures, 73, 74 

 Nutrient broth, 89, 90 



Omelianski's solution for cellulose 

 fermentation, in 



Partial sterilization, effect of, on 

 number of bacteria, 28, 29 



Pasteurized soil, 66 



Peptone saccharose solution, in 

 solution, 98 



