892 



INDEX OF SUBJECTS 



Rhizobium leguminosum, 136 



radicicolum, 136 

 Rhizoctonia, 257, 276, 277, 278, 279, 

 763, 807, 814, 815, 



solani, 257, 277, 803, 806, 807, 808, 812 

 Rhizomyxa, 278 

 Rhizopoda, 313, 331 

 Rhizopus, 3, 238, 247, 258, 259, 266, 

 454, 461 



arrhizus, 247 



nigricans, 247, 495, 803, 809 



nodosus, 247 

 Rhizosphere, 155, 643 

 Rhodobacteria, 59 

 Rhodomonas, 334 

 Rhodophyceae, 230 

 Rhopalomyces, 253 

 Rhynchota, 358 

 River flukes, 345 

 Rivularia, 227 

 Rivulariaceae, 227 

 Robinia, nodule bacteria of, 137 

 Robertus, 355 



Rocks, decomposition of, by micro- 

 organisms, 645 

 Root-knot nematode, 348 

 Root-rots in soil, 807 

 Rose-bengal stain for soil bacteria, 9 

 Rosellinia necalrix, 808 

 Rotatoria (see Rotifers) 

 Rotifers, occurrence of. in soil, 3, 342, 



351 

 Roundworms in soil, 341 

 Rubiaceae, nodule formation in leaves 



of, 139 

 Russula, 257, 276, 278 

 Rusts, 763, 808 



S 



Saccharolytic bacteria, 166, 172 

 Saccharomyces, 251 

 Saccharomycopsis, 251 

 Sainouron, 333 

 Salpingoeca, 333 



Salt concentration, influence of, on 

 biological activities in soil, 301, 787 

 Saltpeter beds, 62 



Salts, influence of, on nitrification, 531 



influence of, on nitrogen fixation, 576 

 Sampling of soil, 19 

 Saprolegniales, 247 



Saprophytism among soil microor- 

 ganisms, 803 

 Sarcina, 58, 154 



flava, 154 



lutea, 490, 491,507, 508 

 Sarcodina, 313, 331 

 Scarabaeidae, 361 

 Scarlet runner bean, nodule bacteria of, 



137 

 Scenedesmus, 228 

 Schinzia leguminosarum, 126 

 Schizomycetes, 236 

 Schizophyceae (see Cyanophyceae) 

 Schizophyllum, 355 

 Schweitzer's reagent, 431 

 Sclerotia, 257 



Sclerotinia, 264, 763, 779, 807, 814, 815 

 Sclerotium, 257 



rolfsii, 807, 808, 812 

 Scytonema, 224, 227 

 Scytonemaceae, 227 

 Seasons of the year, influence of, on 

 biological activities, 40, 779-7S1 



influence of, on numbers of bacteria, 

 31-34 

 Seed germination, role of fungi in, 280 

 Seeds of plants as carriers of bacteria, 



106 

 Segmented worms, 342 

 Selective culture method, 54 



destruction of microorganisms in 

 partial sterilization, 761 



media, use of, in separation of bac- 

 teria, 166 



media, use of, in feeding of protozoa, 

 317 

 Selenates, reduction of, 303, 556 

 Selenium, oxidation of, 91 

 Separation of anaerobic bacteria, 166 

 Septoria, 815 



Seradella, nodule bacteria of, 137 

 Serological method of differentiation 



of nodule bacteria, 134, 137 

 Sick soils, 326, 709, 794, S08 



