CONTENTS xi 



VII 



Contents: Conception of specific irritability. Alteration of specific 

 irritability during and after excitation. Refractory period in 

 various forms of living substance. Absolute and relative refrac- 

 tory period. Curve of irritability during refractory period. 

 Dependence of the duration of the refractory period on the 

 rapidity of the course of the metabolic processes in the living 

 substance. Dependence on temperature. Dependence on supply 

 of oxygen. Theory of refractory period. Refractory period as 

 basis of fatigue. Fatigue as a form of asphyxiation. Alterations 

 of irritability and the course of excitation in fatigue. Recovery 

 from fatigue. The role played by oxygen in recovery. Fatigue 

 as an expression of the prolongation of the refractory period 

 conditioned by the relative want of oxygen. Fatigue of the nerve. 154 



VIII 



Contents: Examples of effects of interference of stimuli in unicellular 

 organisms. Interference of galvanic and thermic stimuli in Para- 

 mecia. Interference of galvanic and thermic stimuli and narcotics. 

 Interference of galvanic and mechanical stimuli. Interference of 

 galvanotaxis and thigmotaxis in Paramecia and hypotin infusoria. 

 Real or homotop interference, apparent or heterotop interference. 

 The two effects of homotop interference of excitations : Summa- 

 tion and inhibition of excitations. Theory of the processes of 

 inhibition. Hering-Gaskell Theory. Inhibition as an expression 

 of the refractory period. Individual possibilites of interference 

 of two stimuli. Interference of an excitating and a depressing 

 stimulus. Interference of two depressing stimuli. Interference 

 of two excitating stimuli. Analysis of the interference of two 

 excitations. Interference of two single stimuli. Conditions upon 

 which the result of interference is dependent. Heterobole and 

 isobole living systems. Intensity of the two stimuli. Interval 

 between the stimuli. Specific irritability and rapidity of reaction 

 of the living system. Latent period. Interference of single stirri- 

 uli in a series. General scheme of the development of the effect 

 of interference. Summation and inhibition. Apparent increase of 

 irritability. Conditions of summation. Tonic excitations. Condi- 

 tions of inhibitions. Various types of inhibition. Interference of 

 two series of stimuli. Relations in the nervous system. Peculiari- 

 ties of the nerve fibers. Conversion of the nerve by relative 

 fatigue from an isobolic into a heterobolic system 189 



