722 



INDEX OF SUBJECTS. 



Soil, bacteria, 240 



aerobic species, 270 



anaerobic species, 270 



at different depths, 241 



distribution, 240 



groups (morphological and 

 physiological), 241 



methods of study (quantitative 

 and qualitative), 242 



nitric, 259 



nitrous, 259 



number, 240 



productive soil, 240 



unproductive soil, 240 

 bacterial substance available, 266 



substance present, 265 

 biological factors of soil-forma- 

 tion, 284 

 calcium, 244, 286 

 carbohydrates (origin), 246 

 carbon dioxide in, 234 

 carbon-nitrogen ratio, 252 

 climatic influences, 232 

 composition (mechanical), 230 

 copper, 291 

 denitrification, 263 



environmental relations, 265 



experimental study, 263 

 drought, 229 

 early, 233_ 

 fermentations, cellulose, 246 



fats, 249 



organic matter, 246 



proteins, 251 



starches, 248 



sugars, 248 



waxes, 249 

 food (plant) assimilation of, 234 



(plant) production in, 234 

 formation of, 284 

 general discussion, 226 

 higher plants in, 239 

 infection, 525 

 iron, 290 

 late, 233 



magnesium, 245, 284, 286 

 manganese, 291 

 medium, as culture, 227 

 mineral food, 237 



mineralization of organic matter, 231 

 moisture relations, 227 



rainfall, 227 



range of, 228 

 molds in, 238 



nitrates, transformation of, 266 

 nitrification, 257 



bacteria (nitric and nitrous), 259 



Soil, environmental relations, 260 

 experimental study, 257 

 nitrates, accumulation, 262 

 nitrates, disappearance, 262 



nitrogen, addition to, 245 



nitrogenous compounds, transforma- 

 tion of, 253 



nitrogen (atmospheric) fixation, aero- 

 bic species, 270 

 anaerobic species, 270 

 biological relations, 269 

 chemical relations, 269 

 cultures for inoculation, 282 

 development of organisms, 276 

 energy relations, 270 

 entrance of organisms, 276 

 environmental relations, 278 

 inoculations, methods of, 280 

 mechanism, 277 

 physiological efficiency, 277 

 resistance of plants to, 279 

 specialization of organisms, 273 

 symbiotic, history of, 278 

 symbiotic (non), history of, 269 

 theories of, 268 

 variations of, 278 



organic acids, accumulation of, 250 

 source of, 250 

 transformation of, 250 



organic matter in, 237 



origin of, 284 



carbohydrates in, 246 

 fats, 249 

 waxes, 249 



oxidation of carbon, 231, 244 

 carbon monoxide, 248 

 hydrogen, 231, 248 

 methane, 248 

 nitrogen, 231, 244 



peptone, transformation of, 266 



phosphorus, 245, 287 



plants (higher in), 239 



potassium, 290 



production of hydrogen, 248 

 methane, 248 



protein bodies in, 251 

 amount, 251 

 quality, 251 



protozoa in, 239 



reaction of, 235 



reduction of nitrates, 264 

 nitrites, 264 

 sulphates, 289 



seasons, influence of, 232 



sulphate reduction, 289 



sulphur, 245, 288 



temperatures of, 232 233 



