Spreading of disease, 142. Squirrels, 108. Stag-head, 240, 244. Starch, 9, 16, 17, 20, 23, 138, 173. Statistics of epidemics, 147. Steeping, 161. Stem diseases, 120. _Stereum_, 206. Sterility of soil, 61. Stimulation, 119. Stimuli, 126, 127, 139. Stock, 262, 264, 266, 282. Stomata, 23. Stool-shoots, 201, 225, 269. Stool stumps, 194, 201. Strangulations, 204, 209. Strawberry, 189, 257. Stripping, 194, 197. Stroma, 217. Structure, 274. Structure of protoplasm, 271. Structure of root-hairs, 40. Struggle for existence, 105, 159, 164, 165, 167, 286. Study of causes, 85. Stumps, 194. Subsoil, 57, 103. Substitutive selections, 286. Suckers, 225, 260. Sugar, 11, 17, 20, 173, 286. Sugar cane, 172. Sugar cane disease, 166. Sulphate, 273. Sulphur, 161, 163, 272. Sulphurous acid, 181. Sun-burn, 240, 241. Sun-cracks, 240, 242. Sundew, 232. Sunflower, 256, 264. Sun-spots, 192. Superstitions, 85. Surface energy, 26. Surface roots, 112. Sweet almond, 173. Symbiosis, 63, 130, 137, 219, 263, 265, 268, 285. Symptoms of disease, 89, 122, 179, 186. _Synchytrium_, 127, 188, 217, 247. Synthesis, 65. _Syringa_, 259. Syringing, 161, 164. Tamarisk, 235. Tannin, 138. _Taphrina_, 218. Tar, 164. Tea, 244. Teazel, 252. Teleutospore, 189, 191. Temperature, 99, 105. Tendencies to ill-health, 91. Tendrils, 125. Teratology, 246, 253, 254, 257. _Tetraneura_, 218. _Tetranychus_, 187, 192. Thawing, 183. _Thelephora_, 206. Therapeutics, 85, 89, 159. Thermotropism, 126. _Thesium_, 112. Thick-skinned organs, 168, 171. Thinning, 96, 105. Thistle, 247. Thrips, 88, 191, 208. Thyloses, 125. _Tilia_, 214. Timber diseases, 119, 120. Timiriazeff, 21. _Tinea_, 206. Tissue diseases, 119. Tobacco, 209. Tobacco powder, 161. Tomato, 171, 219, 230. Top-dry trees, 244. Topical remedies, 161. _Tomicus_, 205. Torsions, 246, 252. _Tortrix_, 254. Toxic agents, 130. Transformation of energy, 25, 28. Transformation of organs, 254, 255. Transmission of acquired characters, 264, 283, 290. Transplanting, 96. Transpiration, 181, 228. Trees, 109. _Trichosphaeria_, 135. _Triticum_, 76. Tumescence, 227, 228. Tunnels, 206. Turgescence, 47, 228, 230. Turnip, 126, 162, 230. Twitch, 113. _Tylenchus_, 238, 248. Ulcer, 231. Unger, 85. Unsuitable soils, 101. Upheaval of seedlings, 179, 183. Uredineae, 114, 134, 136, 145, 169, 188, 189. _Uredo_, 88, 188, 191. Uredospores, 191. _Uromyces_, 116, 188, 191, 266. _Urocystis_, 220. Ustilagineae, 145, 190, 217, 248. _Ustilago_, 116, 117, 175, 190, 219, 255. _Vaccinium_, 128, 288. Variability, 174. Variation, 67, 72, 91, 92, 168, 174, 176, 246, 262, 263, 264, 271, 282, 286, 288, 289. Variegation, 179, 182, 183, 192.