CONTENTS XV 



PAGK 



3. Preyer's Theory of the Continuity of Life. 4. Pfliiger's Idea. 

 B. Critical. 1. Eternity or Beginning of Living Substance. 

 2. The Descent of Living Substance. 



in. The History of Death . 319 



A. The Phenomena of Necrobiosis. 1. Histolytio Processes. 

 2. Metamorphic Processes. B. The Causes of Death. 1. External 

 and Internal Causes of Death. 2. The Question of Physical 

 Immortality. 



CHAPTER V 



STIMULI AND THEIR ACTIONS 



I. The Natdkb of Stimulation . 34s 



A. The Relation of Stimuli to Vital Conditions. 1. The Varieties 

 of the Stimulus. 2. The Intensity of the Stimulus. 3. Trophic 

 Stimuli. B. The Irritability of Living Substance. 1. The Con- 

 ception of Irritability and the Nature of Reactions. 2. The 

 Duration of Reactions. 3. The Conduction of the Stimulus. 



II. The Phenomena of Cell-Stimulation . . . . 3(i4 



A. The Actions of the Various Stimuli. 1. The Actions of 

 Chemical Stimuli, n. The Phenomena of Excitation, h. The 

 Phenomena of Depression. 2. The Actions of Mechanical 

 Stimuli, a. The Phenomena of Excitation, h. The Phenomena 

 of Depression. 3. The Actions of Thermal Stimuli, a. The 

 Phenomena of Excitation, h. The Phenomena of Depression. 

 4. The Actions of Photic Stimuli. o. The Phenomena of 

 Excitation, h. The Phenomena of Depression. 5. The Actions 

 of Electrical Stimuli, a. The Phenomena of Excitation, h. 

 The Phenomena of Depression. B. The Directive Effects of 

 Unilateral Stimulation. 1. Chemotaxis. 2, Barotaxis. 3. 

 Phototaxis. 4. Thermotaxis. 5. Galvanotaxis. C. The Phe- 

 nomena of Over-Stimulation. 1. Fatigue and Exhaustion. 2. 

 Excitation and Depression. 3. Death by Over-stimulation. 



CHAPTER VI 



THE MECHANISM OF LIFE 



I. The Vital Process . . 477 



A. The Metabolism of Biogens. 1. Biogens. 2. Biotonus. B. 

 The Action of Stimuli upon the Metabolism of Biogens. 1. 

 Changes of Biotonus upon Total Stimulation. 2. The Interfer- 

 ence of Reactions. 3. Polar Changes of Biotcjnus and the 

 Mechanism of Axial Orientation upon Unilateral Stimulation. 



II. The Mechanics of Cell-Life ... . . . oU4 



A. The Role of the Nucleus and the Protoplasm in the Life of 

 the Cell. 1. The Theory of the Dominance of the Nucleus in 

 the Cell. 2. Nucleus and Protoplasm as Links in the Metabolic 

 Chain of the Cell. B. Derivation of the Elementary Vital Phe- 

 nomena from the Metabolism of the Cell. 1. The Mechanics of 



