3o8 PROTOPLASMIC ACTION AND NERVOUS ACTION 



while with the intact skin the reversibility relates to 



cations alone. In other words, the two regions exhibit 



different electromotor properties. 



Further experiments' showed that the behavior of 



the organic membrane could be closely imitated by an 



arrangement in which a solution of a weak organic 



acid in a water-immiscible solvent is in contact with the 



salt solutions. In the arrangement already described : 



calomel concentrated membrane- dilute calomel 



electrode salt inclosed salt electrode 



solution system solution 



(e.g., apple) 



the dilute solution is positive and becomes more positive 



with increasing dilution; such a chain is comparable to 



one containing a metal in contact with solutions of its 



salt; e.g.: 



calomel concentrated metallic dilute calomel 



electrode AgNOj Ag AgNOj electrode 



in which also the side containing the dilute solution is 

 positive; AgCl may be substituted for metallic silver 

 with the same result. Similarly the arrangement : 



gave potential differences of a similar order to those 

 found with the organic structure, and varying similarly 

 with the concentration of the dilute salt solution. In 

 other words, the surface of the non-aqueous phase acts 



»Cf. Beutner, Trans. Amer. Electrochem. Soc, XXI (1912), 219; 

 XXIII (1913), 401; American Journal of Physiology, XXXI (1913), 343- 



