358 PROTOPLASMIC ACTION AND NERVOUS ACTION 



interpretation of this effect is that it is an expression of 

 decreased polarizability. This view is confirmed by 

 Bernstein's observation that the electrotonic currents of 

 nerve, which are undoubtedly polarization currents, are 

 also decreased during stimulation/ Any such decrease 

 of polarizability, in a system partitioned by membranes, 

 is an indication of increased permeability of the mem- 

 branes to ions. Recently Ebbecke has again shown that 

 the polarizability of nerve is decreased during stimula- 

 tion;^ he has also found that the same is true of the 

 epidermal cells of the human skin, and he has discovered 

 various interesting parallels between the phenomena 

 exhibited by nerve and by skin, respectively, during and 

 after the passage of the electric current.^ The polariza- 

 bility of the skin and its resistance to constant currents 

 are greatly decreased by either mechanical or electrical 

 stimulation, and this effect is independent of variations 

 of vascularity or other extracellular conditions. The 

 reactions to the constant current are also typical: 

 opposite effects are produced at anode and cathode, 

 as in the polar stimulation of irritable tissues, and the 

 action of salts and anaesthetics on the skin is analogous 

 to that observed with other irritable tissues and cells; 

 e.g., conductivity is increased by solutions of Na and K 

 salts and decreased by Ca salts and anaesthetics."* These 



^ Bernstein, Arch. Anat. Physiol. (1866), p. 614; also Elektrobiologie, 

 chap, vii, p. 130. Cf. also Gotch's article in Schafer's textbook, II, 

 547 ff- 



2 Ebbecke, " Membrananderung und Nervenerregiing," Arch. ges. 

 Physiol., CXCV (1922), 555. 



3 Ebbecke, Arch. ges. Physiol., CXCV (1922), 300, 324. 

 < Ebbecke, ibid., CXC (1921), 230; cf. pp. 247 fif. 



