Xll CONTENTS. 



CHAPTER VI. 

 TRANSPIRATION. 



PAGE 



Transpiration (General Experiments) ... ... ... ... 199 



Water Channels in Root, Stem, and Leaf ; Use of Solutions of 

 Pigments, and of Salts giving characteristic bright-line 

 Spectrum ; Does Water ascend in the Walls or in the 



Cavities of the Vessels? 200 



Mobility of Water in the Vessels 203 



Sucking Force of Transpiring Leaves ; Negative Pressure ... 205 



Influence of External Conditions on Transpiration ; Weighing 



Experiments 207 



Transpiration checked by Bloom, Cuticle, and Cork ; Cuticular 



and Stomatal Transpiration ... ... ... ... ... 209 



Cobalt Paper Method ; Effect of Opening arid Closing of 

 Stomata ; Relation between Transpiration and Absorp- 

 tion 211 



Potometers ; Potometer Experiments ... ... ... ... 214 



Root Pressure ; Escape of Liquid Water from Leaves ... ... 217 



Root Absorption ; Corrosive Action of Roots ; de Saussure's 



Law . , 220 



CHAPTER VII. 

 MOVEMENT IN PLANTS. 



Phototropism (Heliotropism) ; Positive Phototropism ; Dark 

 Chamber for Phototropism Experiments ; Region of Photo- 

 tropic Curvature ; Curvature and Turgidity ... ... ... 222 



Transmission of Stimulus ; Perception of Stimulus ; Perception 



and Transmission ... ... ... ... ... ... ... 223 



Negative Phototropism ; Influence of Light Intensity on Nature 



of Response ; Diaheliotropism ... ... ... ... ... 224 



Geotropism of Root and Shoot ; Moist Chambers for Geotropism 



Experiments ; Region of Geotropic Curvature ... ... 22t> 



Oxygen necessary for Geotropic Curvature ... 227 



