SUBJECT INDEX.

Absidia, [121].
Acarina, [150], [151], [157].
Acid formation by Fungi, [139].
Acidity of soil, [17]; effect on Actinomyces, [140]; relation to nitrification, [36].
Actinomycetes, [119], [134], [139].
Aeration of soil, effect on bacteria of, [61].
Agriotes, [150].
Air supply in soil, [17].
Algæ, agents causing disappearance of nitrate from soil, [12]; associations of, in soil, [105], [106]; blue green, [102 sqq.] (see also [Cyanophyceæ] and [Myxophyceæ]); colonisation of new ground by, [112]; conditions of growth for, [101], [104], [107], [108]; distribution of, [102], [104], [106], [109]; economic significance of, [100], [102]; filamentous, [106]; flora of soil, [101], [112]; formation of humus substances, [112]; fragmentation of filaments, [107], [110]; frequency of occurrence, [102 sqq.]; glucose, effect of, on growth, [108], [109]; green, [104 sqq.] (see also Chlorophyceæ); importance in cultivation of rice, [113]; numbers in soil of, [109], [110]; nutrition of, [107], [108], [110]; producers, of organic substance, [100]; pure cultures of, [107], [111]; relation to gaseous interchange in soil, [113]; relation to soil moisture, [112]; seasonal changes in numbers of, [88]; subterranean, [105].
Alkaloids, as source of nitrogen for fungi, [138].
Alternaria, [119].
Amino-acids, formation of, by algæ, [108].
Amino-compounds, decomposition of, by fungi, [136], [138].
Ammonia, assimilation of, by bacteria, [33], [40], [45]; effect of partial sterilisation on soil content of, [66]; formation in soil, [170]; formation in soil by bacteria, [32 sqq.]; formation in soil by fungi, [135 sqq.], [141]; influence of physical conditions on formation of, [137]; property of attracting Diptera, [159]; utilisation by higher plants, [36].
Ammonium sulphate, effect on fungi, [121], [126], [127].
Anabæna, [102], [112].
Annelida, [149].
Antagonism of salts in soil, [60].
Ants, [153].
Arachnida, [150], [151].
Arctic soil, bacterial flora of, [24].
Areinida, [150], [151], [157].
Armillaria, [132].
Ascomycetes, [119].
Aspergillaceæ, [136].
Aspergillus, [119], [120], [135], [136], [138], [139].
Azotobacter, [6], [41], [95], [96]; assimilation of nitrates by, [45]; decreasing efficiency in liquid culture, [44]; indicator of soil acidity, [44].
Bacillariaceæ, [100] (see also [Diatom]).
Bacillus amylobacter, distribution of, [24].
Bacillus radicicola, [24], [46 sqq.]; inoculation of soil with, [50]; life cycle of, [47].
Bacteria, association with algæ in nitrogen fixation, [111]; anærobic respiration of, [37]; effect of arsenic on, [61]; cellulose destroying, [134]; changes in morphology in culture, [22], [47]; classification of main groups, [23], [25]; composition of cells of, [39]; inverse relationship with protozoa, [10], [79], [82 sqq.]; isolation from soil, [21]; methods of describing, [21]; method of estimating numbers of, [53 sqq.], [80]; nitrogen fixation by, [110], [111]; numbers in relation to algæ, [110]; numbers in soil, [52 sqq.]; oxidation of hydrogen by, [27], [37]; effect of partial sterilisation on, [8], [9], [66], [67]; part played in soil fertility by, [7]; pure cultures, isolation by plating, [20]; seasonal changes in numbers of, [59], [87 sqq.]; effect of salts on, [60]; short time changes in numbers of, [11], [57], [58]; effect of temperature on, [67]; uneven distribution of, [57].
Basidiomycetes, [119], [123], [132].
Beets, attacked by Phoma betæ, [135].
Boletus, [132].
Botrytis, [122].
Bryophyta, [100], [132].
Bumilleria, [105].
Calcium compounds in soil and fungi, [139].
Carabidæ, [150].
Carbohydrates, decomposition by bacteria, [26 sqq.]; decomposition by fungi, [140]; decomposition in soil, [168]; effect on ammonia production in soil, [33]; presence in algal sheath and bacteria, [111].
Carbon, changes in amount in soil, [167]; relationships of bacteria, [27]; relationships of fungi, [133]; source of, for soil bacteria, [39]; sources of, for soil fungi, [139].
Carbon dioxide, assimilation by algæ, [99], [107], [108]; assimilation by soil bacteria, [35], [36], [40].
Carotin, in algæ, [100]; formed by Spirochæta cytophaga, [29].
Cecidomyidæ, [155].
Cellulose, decomposition by bacteria, [27], sqq.; decomposition by fungi, [133], [134], [141]; relation of nitrogen supply to decomposition of, [30]; decomposition in soil, [168]; as source of energy for nitrogen fixation, [43].
Centipedes, see [Chilopoda].
Cephalosporium, [120].
Cephalothecium, [136].
Chilopoda, [157].
Chironomidæ, [155].
Chlorella, [108].
Chlorococcum, [105].
Chlorophyceæ, [100].
Chlorophyll, loss of, from algæ, [108].
Ciliates, classification of, [72]; cyst wall of, [73].
Citric acid, formation of, by fungi, [139].
Cladosporium, [119].
Clamp connections in fungi, [119].
Classification, of algæ, [100]; of bacteria, [23], [25]; of fungi, [131]; of protozoa, [69 sqq.]
Climate, effect of, on algæ, [101].
Clostridium, [41], [44]; as fixer of nitrogen, [6].
Coccomyxa, [104].
Coleoptera, [150], [154], [155].
Collembola, [150], [153], [154].
Colletotrichum, [131].
Commensals, [132].
Conjugatæ, [100].
Cortinarius, [132].
Cotton, destroyed by fungi, [134].
Counting, of algæ, [109]; of bacteria, [53 sqq.]; of fungi, [122]; of protozoa, [77], [79], [80].
Cresol, decomposition of, by bacteria, [22], [24], [31].
Criteria, physiological, of fungi, [128].
Crop growth, effect on fungi, [122].
Cryptomonadineæ, [100].
Cucumber leaf spot, [131].
Cyanamide, decomposition of, by fungi, [136].
Cyanophyceæ, [103] (see also [Myxophyceæ] and [blue-green algæ]).
Cylindrospermum, [102].
Cysts, [68], [73], [74].
Denitrification, by bacteria, [37]; by fungi, [136].
Desiccation, resistance to, by algæ, [106].
Dew, relation to algæ, [101], [113].
Diatoms, [104 sqq.] (see also [Bacillariaceæ]).
Dicyanamide, decomposition of, by fungi, [136].
Dipeptides, formation of, by algæ, [108].
Diplopoda, [157].
Diptera, [150], [154], [155], [159].
Disaccharides and fungi, [134].
Earthworms, abundance of, in soil, [153]; effect of, in soil, [13], [160], [175].
Eel-worms, [149] (see also [Nematoda]).
Elaphomyces, [132].
Enchytræidæ, [149].
Energy, laws of, [165]; relationships of soils, [166]; requirements of soil organisms, [15], [16].
Energy supply, relation of bacterial activities to, [25 sqq.], [40], [44]; sources of, for soil bacteria, [26 sqq.], [40], [43]; supplies of, for soil organisms, [111], [164], [167], [168].
Environmental conditions in soil, [16].
Eremacausis, [2].
Ericales, [132], [135].
Euglena, [99].
Euglenaceæ, [100].
Experimental error, in bacterial counts, [54]; in fungal counts, [124].
Farmyard manure, see [Manure].
Fats, used by fungi, [134].
Fatty acids used by fungi, [134].
Fertility of soil, views on, [2]; effect of decomposition of plant residues on, [1], [165]; effect of organisms on, [175].
Filter paper, destruction of, by fungi, [133]; destruction of, by Spirochæta cytophaga, [28].
Fixation of nitrogen, discovery of, by Berthelot, [5]; by bacteria, [40 sqq.]; by algæ, [110], [111]; by mixtures of bacteria and algæ, [111]; by fungi, [135 sqq.] (see also [Nitrogen Fixation]).
Flagellatæ, [100].
Flax sickness and fungi, [122].
Formaldehyde, as agent for destroying fungi, [141].
Fungi, control of, in soil, [139 sqq.]; counting of, [122]; distribution of, in soil, [119 sqq.], [127]; fertilisers, effect of, on numbers of in soil, [126]; as facultative parasites, [131], [132]; fruiting bodies of, [123]; destruction of hemicelluloses by, [133]; individual, [122], [123]; action on monosaccharides of, [134]; mineral relationships of, [139]; mycorrhizal, [132], [135], [139], [140]; heterocyclic nitrogen compounds and, [138]; occurrence in soil, [118]; qualitative study of, [118]; selective feeding of, [140]; specific determination of, [119].
Fungi imperfecti, [119].
Fusaria, [134].
Fusarium, [119], [120], [122], [128], [133], [136].
Gamascidæ, [156].
Gases of swamp water (Paddy soils), [113].
Gastrodia, [132].
Gelatinous envelope of algæ, [109], [111].
Geographical distribution of azotobacter, [41]; of soil bacteria, [24]; of protozoa, [75], [76]; of soil fungi, [119], [125].
Germination, of algal spores, [107].
Glucose, use of, by algae, [108], [109], [111]; use of, by moss protonema, [109].
Glycocoll, formation of, by algæ, [108].
Granulobacter, [42].
Greenland, bacteria in soil from, [24].
“Grunlandmoor,” fungi in, [126].
Hantzschia, [105].
Hemiptera, [154].
Heterokontæ, [100].
“Hochmoor,” fungi in, [126].
Hormidium, [104].
Humus, the food of plants, [1]; formation of, by fungi, [134], [141]; formation of, in soil, [168]; forest, [132]; fungal hyphæ as constituent of forest humus, [132].
Hydrogen ion concentration, in soil, [17]; effect on fungi of, [124].
Hymenoptera, [150], [154].
Insecta, [150], [157].
Insects, numbers present in soil, [154].
Invertebrata, definition of, [147]; method of investigating, [148]; groups represented, [149]; distribution in the soil, [151]; dominant species and groups, [153]; environmental factors of, [157]; feeding habits, [156]; relation to agriculture, [160]; relation to nitrogen cycle, [161].
Iron compounds, oxidation by fungi, [139].
Isopoda, [150], [151].
Leguminosæ, association with bacteria, [46 sqq.]; enrichment of ground by, [5].
Lepidoptera, [150], [154].
Life cycles, of bacteria, [22], [47]; of protozoa, [72 sqq.]
Lime, effect on fungi in soil, [121], [126].
Lyngbya, [112].
Magnesium compounds, effect on fungi, [139].
Manganese compounds, effect on bacteria, [61].
Manure, farmyard, effect on algæ, [109], [110]; effect on numbers of bacteria, [60]; effect on numbers of fungi, [126]; effect on numbers of insects, [154], [155].
Manure, Artificial, effect on fungi, [127].
Manure, town stable, occurrence of disease organisms in, [132].
Mastigophora, classification of, [71]; species of, [71].
Media, containing nitrates, chemical analysis of, [111]; for counting soil bacteria, [54]; for counting protozoa, [79]; for counting fungi, [119], [123].
Melanconium, [134].
Melolontha, [150].
Methane, oxidation of, by bacteria, [26], [27].
Millipedes, see [Diplopoda].
Mites, see [Acarina].
Mollusca, [149], [157].
Moniliaceæ, [136].
Mucor, [120], [121], [136], [138].
Mucorales, [121], [134].
Mucorineæ, [118].
Mycetophilidæ, [155].
Mycorrhiza, [132], [135], [139], [140].
Myriapoda, [150], [156].
Myxophyceæ, [100] (see also [Cyanophyceæ] and [blue-green algæ]).
Naphthalene, decomposition of, by bacteria, [31].
Naviculoideæ, [100].
Nematoda, [149], [151], [157].
Nitrate, assimilation by algæ, [105], [108], [111]; assimilation by bacteria, [33], [40], [44], [51]; assimilation by fungi, [136], [138]; removal from soil, [12], [112], [171]; variations in amount in soil, [11].
Nitre-beds, [1].
Nitrification, and bacteria, [34]; chemical changes in, [171]; and fungi, [136]; energy supply in, [35]; mechanism of, [1], [3]; and soil fertility, [1], [3].
Nitrites and fungi, [136]; formation by bacteria, [34].
Nitrobacter, [35].
Nitrogen, changes in amount in soil, [167]; cycle in soil, [161]; fixation by bacteria, [6], [40 sqq.]; fixation by fungi, [135], [136], [141]; fixation of, in clover plant, [5]; increase by protozoa of fixation of, [94], [95] ([fig.]); fixation sources of energy for, [43], [49]; gain of, in soil, [174]; in invertebrates, [162]; loss of, by leaching, [112]; loss of, from cultivated soils, [173]; relationships of fungi, [135]; relationships of algæ, [110]-[112]; relationships of bacteria, [32 sqq.], [40 sqq.]; relationships of insects, [162].
Nitrosococcus, [35].
Nitrosomonas, [35].
Nodule Organism of the Leguminosæ, [6], [46 sqq.]
Nostocaceæ, [100], [101], [102], [107].
Oligochæta, [149], [151], [153], [157].
Oospora, [120].
Orcheomyces, [132].
Orchid cultivation and fungi, [132], [140].
Orthoptera, [154].
Oscillatoriaceæ, [100], [102].
Osmotic pressure, influencing effect of salts on bacteria, [50].
Oxalic acid, formation of, by fungi, [139].
Oxidations effected by soil organisms; by bacteria, [26] et seq.; by fungi, [139].
Oxygen, absorption by soils, [4].
Partial sterilisation of soil, [8], [66 sqq.], [96], [178]; influence of organic antiseptics, [177]; limiting factor in, [67], [68].
Pectin, effect of, on fungi, [134].
Pedras negras, [112].
Penicillia, [134].
Pentosans, effect of, on fungi, [134].
Peptones, decomposition of, by fungi, [136], [138]; source of nitrogen for algæ, [108].
Periodicity, of protozoa in soil, [90 sqq.] ([fig.]), [92] ([fig.]), [93].
Phenol, decomposition of, by bacteria, [24], [25], [31].
Phenylalanine, formation of, by algæ, [108].
Phoma, [132].
Phormidium, [106].
Phosphates, availability of, influenced by bacteria, [52]; by fungi, [139]; effect on bacteria, [46], [51], [60].
Photosynthesis, [99], [100], [107], [110], [113].
Phycocyanin, [100].
Physical conditions in soil, [16].
Physiological criteria, of bacteria, [22]; of fungi, [128].
Phycomycetes, [119].
Phytophthora, [132].
Plant disease, and fungi, [139].
Plant residues, decomposition of, in soil, [168]; influence of soil reaction on, [165]; relation to soil fertility, [1], [165].
Plasticity of fungi, [119].
Plectonema, [106].
Potassium salts, effect on bacteria, [60]; influence of bacteria on the availability of, [52].
Protein, decomposition of, in soil, [169]; decomposition by bacteria, [32]; decomposition by fungi, [138], [140].
Protococcales, [100].
Protoderma viride, [105].
Protonema of mosses, [100], [105], [106], [109].
Protophyta, chlorophyll-bearing, [100].
Protozoa, inoculation into soil of, [85 sqq.]; isolation from soil, [69]; classification of, [69 sqq.]; life histories of, [72 sqq.]; species of, in soil, [70 sqq.]; distribution of, in soil, [74 sqq.]; retention of, by soil, [78] ([fig.]); size of, [90]; reproductive rates, [93]; inverse relation with bacteria, [79 sqq.]; presence of trophic forms in soil, [9]; numbers of, in soil, [90], [96], [97]; fluctuations in numbers of, [10], [81] ([fig.]), [82]; external conditions, effect on, [82]; seasonal changes, effect on, [87 sqq.]; weight of, [90].
Pteridophyta, [132].
Pythium, [132].
Reaction of soil, [17].
Reaction of soil, effect on bacteria, [36], [37], [46], [48], [61]; effect on protozoa, [93], [94] (see also [hydrogen ion concentration]).
Relationships of Fungi, commensal, [132]; mycorrhizal, [132]; symbiotic, [132].
Rhizopoda; classification of, [70], [71]; species of, [70], [71].
Rhythm, supposed in ammonification by fungi, [137].
Rhizoctonia, [132].
Rhizopus, [119], [120].
Rice plant, aeration of roots, [113]; physiological disease of, [113].
Rock Phosphate as base for nitrifying organisms, [36].
Rothamsted, Broadbalk plot 2 (Farmyard Manure) algæ, [109]; fungi, [125], [127]; Insects, [152].
Rothamsted, Broadbalk plot 3 (Unmanured) algæ, [109]; fungi, [120], [122], [127]; Insects, [152].
Rothamsted, Broadbalk Plots 10, 11, and 13; [122], [127].
Rothamsted, Barnfield Plot 1-0 (Farmyard Manure), Protozoa, [80].
Rothamsted, unmanured grass plot, [120].
Russula, [132].
Rusts, [119].
Saccharomyces, [120].
Saprophytes, facultative, [131].
Saprophytism and algæ, [108], [110].
Scenedesmus, [108].
Seasonal fluctuations in numbers of soil organisms, [12], [87 et seq.], [125].
Selective media, use of, in isolation of soil bacteria, [21].
Serological tests, separation of varieties of B. radicicola by, [48].
Slugs, see [Mollusca].
Smuts, [119].
Snails, see [Mollusca].
Soil; comparison of, by volume, [17]; effect of depth below surface on algæ, [101], [104], [109], [110], [113]; effect of depth below surface on insects, [151]; effect of depth below surface on fungi, [121], [126], [127]; effect of various treatments on fungi, [126], [127], [132]; environmental factors in, [16]; inoculation of, for leguminous plants, [50]; moisture (see [Water supply]); population, control of, [177 sqq.]; population, methods of investigation, [10], [15]; sterilisation and fungi, [137], [138], [141] (see [Partial Sterilisation]); stored, survival of algæ in, [107]; type and fungi, [121], [126], [127].
Soil conditions, effect on bacteria, [33], [36], [37], [40], [46], [48], [50], [59 sqq.]; effect on protozoa, [82].
Soil fertility, see [Fertility of soil].
Spicaria, [120].
Spiders, see [Areinida].
Spirochæta cytophaga, [28], [43].
Spore forming bacteria in soil, [23], [34].
Spore, fungus, inhibition of formation, [123]; presence in air of, [118].
Standardisation of cultural methods for soil bacteria, [54 sqq.]
Starch, decomposition of, by fungi, [134].
Stichococcus, [108].
Straw; effect on nitrate production in soil, [33]; manure, [29]; rotting of, [30].
Sulphur oxidation, by bacteria, [37]; by fungi, [139].
Symbiosis, of Azotobacter with other organisms, [42], [43], see also [Mycorrhiza] and [Nodule organism].
Symphyla, [150], [151], [157].
Symploca, [112].
Tachinidæ, [150].
Tannins, used by fungi, [134].
Temperature of soil and fungi, [127], [140].
Termites, [160].
Testacella, [149].
Thiospirillum, [37].
Thysanura, [154].
Thysanoptera, [154].
Tipula, [150].
Toluene, decomposition by soil bacteria, [31].
Tolypothrix, [112].
Trichoderma, [119], [120], [122], [134].
Trochiscia, [105].
Tropisms, [157].
Ulothrix, [105].
Ulotrichales, [100].
Urea, by fungi, [136], [138].
Uric acid, utilisation of, by fungi, [138].
Vaucheria, [104], [106].
Vitality, retention of, by algæ and moss protonema, [105], [107].
Water; supply in soil, [17]; and algæ, [112]; bacteria, [50], [61], [82]; fungi, [127]; protozoa, [82].
Wireworms, [155].
Wood, decay of, [134].
Woodlice, [150]; (see also [Isopoda]).
Yeasts, [138].
Zygnema, [104].
Zygorrhynchus mœlleri, [119], [120], [121].

PRINTED IN GREAT BRITAIN BY THE UNIVERSITY PRESS, ABERDEEN