300 PROTOPLASMIC ACTION AND NERVOUS ACTION 



are known to vary with the composition of the non- 

 aqueous phase and with the electrolyte content of the 

 aqueous phase; i.e., ions have a special influence, 

 although surface-active substances other than electro- 

 lytes may also have an effect, as already shown. The 

 case of the living cell falls partly in this general category. 

 Suspended cells travel in the electric field, usually 

 toward the anode; and the rate and even the direction 

 of this travel may be changed, just as in non-living 

 suspended particles, by changing the electrolyte content 

 of the medium; especially active in this regard are 

 H ions and the ions of polyvalent metals. Constant 

 currents passed through living tissues (muscle) effect 

 transport of fluid. This is a special case of electrical 

 endosmose; evidently any passage of electricity through 

 a cell must involve some displacement or transport 

 of fluid, a fact which must be considered in relation to 

 physiological processes hke secretion, absorption, and 

 cell-division. The potentials between suspended particles 

 and suspension-media are apparently in large part adsorp- 

 tion potentials; their range is comparatively narrow, usu- 

 ally between 0.02 and 0.05 volt; according to Freundlich 

 they represent the potentials between an adhering im- 

 mobile layer of solution and the mobile layer adjoining.^ 



These facts, while relevant to the general theory of ^ 

 the bioelectric potentials, do not in themselves explain 

 sufficiently the special peculiarities of the latter. Appar- 

 ently the closest resemblances are with electrode poten- 

 tials; e.g., those between a metal and an adjoining 

 solution. From the physiological point of view the most 



^ Freundlich, Kapillarchemie, p. 243 ; Report on the Physics and 

 Chemistry of Colloids, Faraday Society and Physical Society of London 

 (London, 1921), p. 146. 



