Index 
Sequoia, 241 
Seven-leaf clover, 109, 287 
Sheep, 309 
Sheep-killing grasses, 261 
Shingle, 163 
Silva Caledonia, 229 
Sisyrhinchium, 234 
Snares Island, 107 
Snowdrop, 204 
Soil, 48 
Soldanella, 185 
Solomon’s seal, 146 
Somaliland, bush of, 312 
Spanish flora, 219, 220, 255, 276, 308 
Spartina association, 163 
Sphagnum, 71, 72, 73, 91 
Spiranthes, 233 
Spraying of weeds, 258 
Spruce, 291 
Spruce-galls, 200 
Spurs of petals, 119, 120 
Statistical methods, 183 
Statolith theory, 147 
Steppe grasses, 263, 266 
Steppes, invasion of, 232 
Stimulus of evil, 327-338 
Stocks, 303 
Streptocarpus, 79 
Struggle for existence, 156 
Succulents, 172-173 
Sudd of Nile, 133, 134 
Sugars, 119, 328 
Summit floras, 89 
Sundew, 150 
Sunshine, effects of, 187, 233, 240 
Sycamore, 291, 291, 292 
TACITUS, 229 
Tannin, 178 
Tendrils, 148 
Teneriffe, 275 
Temperature, extremes of, 34 
Tertiary flora, 218, 276 
Thais, 108 
Thistles, 257 
Thorns, 25, 174-176 
Tibetan plants, 94 
Tillering of corn, 263 
Tococa, 206 
Torenia, I10, 155 
Tracheid, 190 
Trades dust, 37 
Trapella, 129 
Tree-ferns, 80 
Tropical forests 316-326 
Tundra, 92 
Tussocks, 271 
ULE, Dr., 209 
Ultraviolet rays, 187 
Urboden, 19 
Vaccination, 58 
Variation in flowers, 120 
Variations, origin of, 182, 183, 327, 328 
Vaucheria, 162 
Venus’ flytrap, 201 
Victoria regia, 132 
Viola, changes in, 184 
Volvox, 45 
Vossia, 134 
WALNuT, Burbank’s, 290 
Water-lily zone, 130, 132 
Water plants, 125, 279 
Water pollution, 139 
Wax of flowers, 120 
Weathering of rocks, 68 
Weeds, 95, 231, 232, 254-258, 311 
Weissmannism, 291-298 
Welwitschia, 179 
Werchojansk, 236 
Wheat, 254, 284, 285, 288, 334 
Willows, 130, 132, 139 
Wind, effect of, 189 
Wood, 24, 190, 245 
Wood anemone, 26 
Wood-floor, flora of, 244 
Worms, 50, 197 
Wounds, effect of, 331, 333, 334 
Wulfenia, 181 
XANTHOPHYLL, I11 
YIELD of crops, 259 
Young leaves uv. old ones, 152 
ZosTERA association, 158 
Printed by BALLANTYNE, Hanson & Co, 
Edinburgh & London 
