Ternetz, 135. Treub, 112. Truffaut, 69. VERKADE and Söhngen, 134. Von Ubisch, 109. WAKSMAN, 37, 118, 120, 121, 123, 125, 126, 134, 136. Waksman and Cook, 136. Wann, 111. Warington, 4, 34. Waynick, 42. Welwitsch, 112. Werkenthin, 120, 121. West, 88, 105. Whiting, 36. Wilfarth, 46. Winogradsky, 4, 6, 34, 41, 44. 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.