238 PROTOPLASMIC ACTION AND NERVOUS ACTION 



on the electromotive force of cadmium-amalgam cells/ 

 In the case of contact-potentials between water and other 

 dielectrics, Grumbach^ found in general that organic 

 compounds which lower the surface-tension of water 

 decrease these potentials. With CH3OH, C2 HgOH, and 

 C4H9OH the effect increases in the order of increasing 

 molecular weight; the curves relating potential change 

 and concentration resemble the corresponding curves of 

 surface-tension and adsorption. The observations of 

 Loeb and Beutner^ on the contact-potentials between 

 organic membranes (apple skin) and electrolyte solutions 

 containing alcohols also show a decrease of P.D. with 

 the addition of alcohol. With the first three alcohols 

 the effect increased was in the order of Ci<C2<C3 

 (p. 302). Similar results were obtained with solutions of 

 lecithin in guaiacol. The concentrations required to 

 produce a decided influence on the potentials were, 

 however, much higher than the physiologically effective 

 or narcotizing concentrations. 



Traube nevertheless regards the influence of surface- 

 active substances on the contact-potentials between the 

 living cell and the medium as an important factor in the 

 physiological effect, and Macallum has expressed a 

 similar view."* It is doubtful, however, if this can be 

 generally true, since the bioelectric potentials are not 

 necessarily decreased in anaesthesia. For example, in 

 pure sugar solution, which produces in muscle effects 



* Cf. Traube, "Theorie der Narkose," Arch. ges. Physiol., CLIII 

 (1913), 276; cf. p. 303. 



2 Ann. de Chim. et de Phys. (191 1). 



3 Biochem. Zeitschrift, LI (1913), 300. 



4 A. B. Macallum, Surface Tension and Vital Phenomena, University 

 of Toronto Studies (1912), No. 8, pp. 68 £f. 



