672 



SCIENCE 



[N. S. Vol. XXXVII. No. 957 



there were pre-Ojibwa Algonkians in this 

 region — probably the Cheyenne. Altogether, 

 there is much good information and not a 

 little speculation of a somewhat doubtful 

 character in this volume. Some of the ma- 

 terial deserves to be gone over again and 

 made more of. 



Alesandee F. Chamberlain 

 Olabk University, 

 WoRCESTEE, Mass. 



SPECIAL ABTICLES 



THE NATURE OF THE SUBSTANCES WHICH CAUSE 

 THE BIOELECTRICAL POTENTIAL DIFFERENCES 



In previous papers' we have shown that the 

 potential differences at the junction of the 

 intact surfaces of plants and aqueous salt so- 

 lutions exhibit sharply defined and reversible 

 changes with the change in the concentration 

 of the salt solution. The sense of these 

 changes is such that we can speak of a reversi- 

 bility for kations and the order of magnitude 

 corresponds nearly with that calculated by 

 Nernst's formula. A similar change was ob- 



of the order of magnitude of the so-called cur- 

 rent of injury found in living organs. Finally 

 "we observed that the bioelectrical potential 

 difference approaches a limit for increasing 

 concentrations of the salt solution. 



These characteristics are so definite that we 

 undertook an investigation of the nature of 

 the substances which are responsible for the 

 potential differences at the junction of living 

 organs and aqueous solutions. It was first as- 

 certained that solid proteins, like gelatine or 

 coagulated white of egg, show none of the 

 potential differences characteristic for living 

 organs. These characteristics were shown, 

 however, by certain fatty compounds, like 

 phosphatides (lecithin and kephalin), oleic, 

 stearic and palmitic acids, and to a lesser 

 degree by triolein. For technical reasons it 

 was necessary to dissolve these substances in 

 guaiacol or kresol.^ 



At the junction of a soluble lecithin solu- 

 tion and aqueous solutions were found the 

 same changes in E.M.F. with the change in the 

 concentration of the salt solution as we had 



served on the injured surface of certain plants 

 and on animal organs. 



We found, moreover, that the potential dif- 

 ference becomes smaller if we substitute an 

 equimolecular acid solution for the salt solu- 

 tion, and we pointed out that this difference is 



> Science, XXXIV., 884, 1911; XXXV., 970, 

 1912. Biochem. Ztsohr., 41: 1, 1912; 44: 303, 

 1912. 



previously found at the junction of a living 

 organ (e. g., the leaf of Ficus elasticus) and 

 the aqueous solution, and moreover we noticed 

 also the characteristic acid effect. In order 

 to show to what extent the electromotive be- 

 havior of a lecithin solution resembles that of 



"Beutner, Jour. Amer. Chemical Society, 35: 

 344, 1913. 



