X TABLE OF CONTENTS. 



PAGE 



B. Fertile Seeds. Hybridization. Apogaray . . . 241 



C. Variability, Constancy, Heredity . 243 



D. Special Creation and the So-called Theory of Natural Descent . 244 

 Appendix: The Life-period of Plants 250 



PART Y. 



The General Chemistry and Physics of Plant-life. 



I. Chemical Physiology 252 



Selection 257 



The Cyclic Course of Food-substances 258 



II. The Physiology of Growth 253 



A. Active and Passive Growth 261 



B. The Results of Unequal Growth 261 



(a) Tissue-tension 262 



(V) Curvatures 263 



(c) Torsions 264 



C. Molecular Organization of Plant-structures 266 



III. Temperature, Light, Gravity, and Other Factors in Their Re- 

 lation to Plant-life 268 



A. Effects of Temperature 268 



(a) Production of Warmth and Cold 268 



(b) The Effect of Temperature upon Plant-life .... 269 



B. Effect of Light 270 



(a) Production of Light 270 



(b) Influence of Light upon Plant-life 271 



C. Influence of Gravity ......... 275 



D. Electricity, Moisture, Water- currents, Radiating Heat . . 276 

 IT. The Physiology of Plant-movements 277 



A. Classification of Movements according to Cause. The Outward 



Manifestation of Some Movements 277 



B. Hygroscopic Movements ........ 278 



C. Autonomous Movements 279 



D. Irritable Movements 280 



Mimosa 280 



Behavior of Tendrils. Conduction of Stimuli. The Function of 



Irritable Movements 281 



E. The Physiology of Twining 283 



PART VI. 

 Classification of Plants. Taxonomy . . 286 



ALPHABETICAL INDEX 293 



