xii CONTENTS 



CHAPTER III 

 ACTION OF THE DENSITY OF THE MEDIUM UPON PROTOPLASM 



PAGE 



1. Introductory Remarks upon the Structure of Protoplasm and the 



Physical Action of Solutions ....... 70 



2. Effect of Varying Density upon the Structure and General 



Functions of Protoplasm ....... 74 



3. Acclimatization 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 OF 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 

 EFFECT OF GRAVITY UPON PROTOPLASM 



1. Methods of Study 112 



2. Effect of Gravity upon the Structure of Protoplasm . . .113 

 3. Control of the Direction of Locomotion by Gravity Geotaxis . 114 

 Literature 124 



CHAPTER VI 

 EFFECT OF 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 



