312 PROTOPLASMIC ACTION AND NERVOUS ACTION 



explanation on the li3rpothesis that dissolution' and 

 re-formation of the semi-permeable surface layers of the 

 cells are the main factors in the production of the normal 

 electromotor variations. The specifically vital functions 

 of metabolic construction and destruction which 

 determine the physical properties of the cell structures 

 would thus determine also the normal variations of the 

 bioelectric potentials. The general physico-chemical 

 conditions of these potentials are of a kind present at all 

 phase-boundaries; but the special peculiarities of the 

 protoplasma boundary layers, and hence of the dependent 

 electromotor phenomena, are determined by the specific 

 metabolic activities of the protoplasm and vary with 

 these activities. It is evident that metabolic destruction 

 and re-formation of surface-films would involve electromo- 

 tor variations; and in those cases where the film- 

 material is susceptible to chemical alteration (e.g., oxida- 

 tion or reduction) under the influence of the local 

 electric currents thus arising, the conditions would also 

 be furnished for the processes of spreading and trans- 

 mission, which are essential to stimulation. Conditions 

 closely resembling in their general features those just 

 defined are in fact realized in the passive iron model and 

 related inorganic systems described above. 



NORMAL BIOELECTRIC VARIATIONS OR 

 ACTION-CURRENTS 



The present view, therefore, refers the normal bio- 

 electric phenomena to variations in the phase-boundary 



^ The precise nature and degree of this alteration are unkno\\Ti; the 

 term "dissolution" may be regarded as indicating an alteration sufficient 

 to deprive the surface layer temporarily of its properties as a membrane, 

 i.e., as a semi-permeable partition. This efifect is equivalent to increase 

 of permeability. 



