xii CONTENTS 



CHAPTER III 

 Action op the Density of the Medium upon Protoplasm 



PAGE 



§ 1. Introductory Remarks upon the Stricture of Protoplasm and the 



Physical Action of Solutions .... . . 70 



§ 2. Effect of Varying Density upon the Structure and General 



Functions of Protoplasm 74 



§ 3. Acolitiiatization to Solutions of Greater or Less Density than the 



Normal . ... . ... 85 



§ 4. Control of the Direction of Locomotion by Density — Tonotaxis . 89 



Literature . . . 93 



CHAPTER IV 

 Action op Molar Agents upon Protoplasm 



§ 1. Effect of Molar Agents upon Lifeless Matter . . 97 



§ 2. Effect of Molar Agents upon the Metabolism and Movement of 



Protoplasm . ... ... 98 



§ 3. Effect of Molar Agents in Determining the Direction of Locomo- 

 tion — Thigmotaxis (Stereotaxis) and Rheotaxis . . 105 



Literature . .... . . 110 



CHAPTER V 



Eppect op Gravity upon Protoplasm 



§1. Methods of Study 112 



§ 2. Effect of Gravity upon the Structure of Protoplasm . . . 118 



§8. Control of the Direction of Locomotion by Gravity — Geotaxis . 114 



Literature ... . . 124 



CHAPTER VI 



Effect op Electricity upon Protoplasm 



§1. Concerning Methods 126 



§ 2. The Effect of Electricity upon the Structure and General Func- 

 tions of Protoplasm .... . 129 



§ 3. Electrotaxis . . 140 



Summary of the Chapter . 151 



Literature ... 152 



