CONTENTS. XV 



PAGE 



Classification of Soils 238 



Absorption and Retention of Moisture by Soils 239 



Chemical Absorption by Soils 243 



Condensation of Gases by Soils 244 



Root-absorption of Saline Matters from Soils 244 



Temperature of Soils . 245 



Effects of Roots upon Soils 246 



Ash CoNSTiTDiSNTS of Plants 246 



Amount and Distribution 246 



Composition 247 



Water-cultdre 248 



Apparatus . 249 



Nutrient Solutions . 250 



Method of Practice 251 



OrFioE OF THE Different Ash Constituents 252 



Potassium 252 



Calcium and Magnesium 253 



Phosphorus 253 



Iron 254 



Chlorine 254 



Sulphur 255 



Sodium ... 255 



Rarer Constituents 255 



CHAPTER IX. 



TRANSFER OF WATER THROUGH THE PLANT. 



The Relations of Watek to Tissues 257 



Transfer of Water in Woody Plants • 258 



Determination of the Path and Rate of Transfer 259 



Rate of Ascent of Water in Stems 261 



Effect, upon Transfer of Water, of Exposing a Cut Surface to the Air 263 



Pressure and Bleeding 264 



Exudation of Water from Uninjured Parts of Plants 267 



Teanspikation 2^° 



Stomata 268 



Mechanism -^o" 



Relations to External Influences 270 



Amount of Water given off in Transpiration 271 



Transpiration compared with Evaporation proper 275 



Effect of Moisture in the Air upon Transpiration 275 



Effect of the Soil upon Transpiration 276 



Relations of Temperature to Transpiration 277 



Effect upon Transpiration of Light 277 



Of different Rays of the Spectrum 278 



Of Mechanical Shook 278 



BelatioL of Age of Leaves to Transpiration 279 



