CONTENTS. 



PAGE 



Introduction 343 



Instrumentation and conditions of experiment 343 



Materials 344 



Role of water in reproductive activity 346 



Experiments with soil moisture 348 



Experiments with evaporation rates 349 



Role of water in the preservation of life 350 



Relation of water-loss in insects when exposed to changes in the relative 

 humidity of the surrounding medium, and its effect on the activities 



of such organisms 354 



Experiments upon evaporation, transpiration, and behavior 355 



Role of water in hibernation 366 



Entrance into hibernation 366 



Activities during hibernation 371 



Water relation of soils and hibernating beetles 371 



Emergence from hibernation 372 



Summary and discussion upon the relation of water to hibernation 373 



Effect of changes in water content upon alterations in tropic activities 375 



Experiments upon the role of water in geotropism 376 



Relation of temperature to outgo and intake of water 377 



Metabolism and water relation 378 



General discussion upon the role of water in living things 379 



Summary and conclusion 381 



Bibliography , 382 



