238 



INDEX 



Soil formatioiij Biological agencies, 



Soil formation, Chemical agencies, 

 76 



atmosphere, 76 

 water, 77 

 Soil formation, Physical agencies, 

 72 

 ice, 75 



temperature, 72 

 volcanoes, 75 

 water waves, 75, 74 

 wind, 73 

 Soil formers, bacteria as, 18, 19, 



20 

 Soil gain in nitrogen, 149, 151, 



155, 163-165 

 Soil, influence of carbohydrates on, 



149 

 Soil inoculation, 148-15I5 165- 



170 

 Soil inoculation, factors govern- 

 ing, 150 

 Soil, loss of nitrogen from, 134, 



Soil, organic matter in, 107 



Soil, organic matter, function, 109 



Soil reclaiming, 1 97-1 99 



Soil, residual, 83 



Soil structure, 85 



Soil structure, influence of organic 



matter on, no 

 Soil texture, 84 

 Soil, transported, 84 

 Spallanzani, 4 

 Spermatophytes, 13 

 Spirilla, 23 

 Spontaneous generation, 3 



Spore formation, 32, 33_ 



Stains, first used on bacteria, 7 



Sterilization, 66 



Sterilization, early attempts, 4, 5 



Sulfur as a disinfectant, 69 



Sulfur cycle, 102 



Sulfur in soil, 81 



Sulfur requirements of plants, 89 



Symbiosis, 60 



Symbiotic bacteria, loi 



Symbiotic, non-, bacteria, lOl 



T 



Temperature in soil formation, 72 

 Temperature influence on bacteria, 



62 

 Temperature, maximum, 62, 63, 



64 

 Temperature, minimum, 62, 63, 



Temperature, optimum, 62, 63, 



64 



Temperature, of soil, 109 

 Texture, of soils, 84 

 Thallophytes, 14 ^ 

 Thermal death point, 65 

 Thermophilic bacteria, 63, 64 

 Toxicity of alkali salts, 194, 195 

 Toxicity of alkali salts, variation, 



195 



Toxins, 47 



Transported soils, 84 



Tubercles on legumes, 158, 159, 



160 

 Tyndall, 7 



u 



Utah soil, composition, 173 



