CONTENTS 
CHAPTER PacEe 
I. IRRITABILITY ASA SIGNOFLIFE. . .. 2 4 
The Characteristics of Living Matter. Irritability. 
Functional Changes as a Sign of Irritability. Functional 
Changes in the Nerve Fiber. 
II. CHEemicaL SIGNS OF IRRITABILITY IN THE NERVE 
FIBER... * * #@ » TO 
Signs of Metabolic Activities in 4 Tissue. Indirect Evi- 
dence for Presence of Metabolic Activity in the Nerve 
Fiber. Direct Evidence. Experimental Methods with Non- 
Medullated Nerve Fiber. Medullated Nerve Fiber. Is 
Carbon Dioxide Produced by Living Processes? Discussion. 
TIT. CHemicaL SIGNS OF IRRITABILITY IN THE NERVE: 
FiIneR—Continued » a « 34 
Increased Metabolism on Stimulation. Experimental. 
Electrical Stimulation. Other Stimulations. Discussion. 
IV. EXcITATION AND CONDUCTION : a See 
Excitability and Metabolism. Degree of Excitability € Com- 
pared with Metabolism. Effects of Narcotics. Lower 
Concentration. Higher Concentration. Direction of the 
Nerve Impulse and Metabolic Gradient. Velocity of the 
Nerve Impulse and Carbon Dioxide Production. 
V. CHemicaL SIGNSor LIFE. . . . wae 189 
Resting Metabolism in Seeds. Increased Metabolism in 
peas on Injury. Other Tissues. A Chemical Sign of Life. 
VI. Conciustons eK OK d Ce Siow 2. NOs 
Summary. Other Criteria of Life. Functions of Resting 
Metabolism. Metabolism and Irritability. Chemical Con- 
ditions in the Living Processes. Quantity of Life. 
APPENDIX. THE BIoMETER: Howto UseIT . . . 109 
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