890 



INDEX OF SUBJECTS 



Plasmodiophora brassicae, 236, 803, 

 812, 814, 816 



Plasmodium formation, 236 



Plasmoptic mycorrhiza, 277 



Plastic equivalent, 417 



Plate counts compared with micro- 

 scopic counts, 27 



Plate method, for determining numbers 

 of soil bacteria, 13 

 for isolation of bacteria, 55 



Plates, preparation of, 21 



Plathelminthes, 341, 345 



Plectoascineae, 251 



Plectonema, 225, 227 



Plectridium, 173, 178, 204 

 peclinovorum, 173 



Pleclus, 346, 349, 350 



Pleurococcus, 228, 234 



Pleuronema, 335 



Pleurotaenium, 229 



Pleurotricha, 336 



Podocarpus, nodule formation by, 

 138, 139 



Poisons, influence of, on actinomyces, 

 302 



Poisson series, 26 



Polydesmus, 355 



Polypodiaceae, mycorrhiza formation 

 by, .273 



Polypseudopodius, 334 



Polytoma, 334 



Porrho?nma, 355 



Potassium, available, 662 

 in soil, 625 



influence of, on nitrogen fixation, 577 

 transformation of, in soil, 615, 660-662 



Potato as reducing agent, 171 



Potato scab, 301, 616 



Potato wart, 236 



Potatoes, symbiosis with mycorrhiza 

 fungi, 274 



Primitive activities of microor- 

 ganisms, 645 



Prismatolaimus, 350 



Probable error in bacterial counts, 26 



Proleptomonas, 333 



Proof of microbial activities in soil, 5 



Prorhynchus, 345 



Prorodon, 335 



Protein content of natural organic 

 materials, 470 



decomposition of, 299, 475, 480, 679 



hydrolysis, 473 



physical and chemical properties of, 

 470 



synthesis by Azotobacter, 570 



synthesis, in soil, 479 

 Protein decomposing bacteria, num- 

 bers of, in soil, 38, 175 

 Protein-forming bacteria, 183 

 Proteins of microorganisms, decom- 

 position of, 268 

 Proteolytic bacteria, 154, 166 

 Proteomyxa, 331 

 Protoasci, 250 

 Protococcus, 234 



Proteus vulgaris (see Bad. vulgar e) 

 Protoderma, 228 

 Protomastiginae, 333 

 Protosiphon, 228, 233 

 Protozoa, 311-340 



autotrophic forms, 315, 316 



classification of soil protozoa, 313, 

 329 



cysts of, in soil, 45 



heterotrophic forms, 315 



importance of, in soil, 336 



influence of, on nitrogen fixation, 

 338 



isolation of pure cultures, 320 



life history of, 324 



media for cultivation of, 317 



methods of determination of num- 

 bers, 45 



morphology of, 311-314 



numbers of, in the soil, 45-50, 327 



occurrence of trophic forms and cysts 

 in soil, 3, 325, 329 



physiology of, 314 



reproduction of, 312 



staining of, 323 

 Protozoan theory of soil fertility, 757 

 Prowazekia, 333 

 Pseudococcus, 362 

 Pseudochlamys, 332 

 Pseudodifflugia, 332 



