4o6 PROTOPLASMIC ACTION AND NERVOUS ACTION 



is indicated by the facts of electrostenolysis and by the 

 chemical effects produced by intense electrical discharges 

 (sparking, etc.). 



The general fact that chemical effects are produced 

 in protoplasm by the electric current and that protoplasm 

 produces electric currents in its activity, when considered 

 in conjunction with the further fact that these phenomena 

 are dependent on the structure of the living system and 

 disappear with the loss of semi-permeabihty (as at 

 death) — as well as the various other facts reviewed above, 

 which relate stimulation to membrane changes — indicates 

 clearly that the electrical sensitivity of living protoplasm 

 is intimately connected with the presence of the semi- 

 permeable partitions or surface-films. These partitions 

 have high electrical resistance and are therefore highly 

 polarizable; they are also extremely thin; hence when 

 they are polarized by the passage of a current there is a 

 correspondingly steep fall of potential between their 

 opposite faces. The hypothesis naturally suggests itself 

 that the existence of these steep gradients is the essential 

 condition on which the chemical action of the electric 

 current in living protoplasm depends. 



We have recently attempted to put this hypothesis 

 to an experimental test by passing electric currents 

 through electrolyte solutions partitioned by artificial 

 membranes, combining extreme thinness with high elec- 

 trical resistance.^ Such a membrane, consisting of a thin 

 film of rubber or other insoluble non-conducting material 



* R. S. Lillie and S. E. Pond, "Chemical Effects Produced by Passing 

 Electric Currents through Thin Artificial Membranes of High Electrical 

 Resistance," American Journal of Physiology (1923); Proceedings of the 

 American Physiological Society, December (1922). 



