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 Transcriber’s Notes Inconsistent and archaic or unusual spelling, capitalisation, italicisation, hyphenation, etc. have been retained, unless mentioned below. The names and classifications of the organisms as used in the book do not always conform to modern names and classifications; these have not been changed. Depending on the hard- and software used and their settings, not all elements may display as intended. Page 14, table, lower right hand cell: the data given add up to 8, not to 9. Page 47, ·9 × ·18 in size: the source document does not include the units; presumably the sizes are in microns. Page 118, endnote 8c (2×): this note does not exist. Subject Index, entry Zygorrhynchus mœlleri: also refers to Zygorrhynchus vuilleminii. Changes made: Footnotes, tables and illustrations have been moved out of text paragraphs; some tables have been split or re-arranged. Several minor obvious typographical, punctuation and spelling errors (including accents) have been corrected silently. In several cases spelling differences (mainly of proper names) between the text and the index and endnotes have been standardised. In the indexes and in tables some ditto marks have been replaced with the dittoed text. Some page references have been corrected to indicate the correct page number. Indented text under illustrations is not present as such in the source document, but has been transcribed from the illustration for legibility and ease of reference. Some tables have been re-arranged or split to fit the available width. Page 28, 29: MacBeth changed to McBeth as elsewhere (in the Author Index the entries MacBeth and McBeth have been merged). Page 32, formula: 30 changed to 3O.