November 5, 1915] 



SCIENCE 



645 



cible salt determines the E.M.F. On the basis 

 of this assumption Beutner has been able to 

 explain the observed phenomena thermo- 

 dynamically, and his theory accounts for all 

 E.M.F. at phase boundaries. 



It follows from this theory that a spot of 

 tissue in contact with distilled water should be 

 positive to one in contact with a physiological 

 salt solution, which is actually the case. 



It was known that if we lead o£F from two 

 spots of a muscle with a KCl and NaCl solu- 

 tion of the same concentration, the spot in 

 contact with KCl appears negative to that in 

 contact with NaCl. Loeb and Beutner could 

 show that this was also true for the boundary 

 between oleic acid or lecithin and salt solutions, 

 and it was explained by Beutner on the as- 

 sumption (which could be verified) that KCl 

 is more soluble in the water immiscible phase 

 than NaCl, that the CI combines with some 

 constituent of the water immiscible phase, and 

 that the CI ion, being the common ion, deter- 

 mines the E.M.F. 



2. It is well known that an injured spot of 

 a tissue is negative to a non-injured spot (cur- 

 rent of injury), and this is explained on the 

 basis of Bernstein's or Bayliss's theory by as- 

 suming that the specific cation permeability 

 of the membrane is abolished by the injury 

 and that the anions will also reach the outer 

 boundary of the injured spot. Loeb and 

 Beutner have published experiments which 

 show that the so-called current of injury has 

 nothing to do with an alteration of permeabil- 

 ity, but that it is in all probability due to the 

 existence of an internal E.M.F. situated at the 

 internal boundary of the membrane.^ If it is 

 true that the junction of the outer boundary 

 of an organ, e. g., an apple, with a salt solu- 

 tion must become the seat of an E.M.F., the 

 same must be true for the boundary of the 

 membrane with the internal liquids of the 

 tissues containing electrolytes. If we could 

 show that this internal E.M.F. is generally 

 smaller than the E.M.F. at the outside sur- 

 face when we lead off from the latter with a 

 physiological salt solution, the so-called current 



5 Loeb and Beutner, Biochem. Ztschr., 1912, 

 XLIV., p. 304. 



of injury woiild find a simple explanation. As 

 a matter of fact, acids, KCl, and other sub- 

 stances give rise to negative potentials if com- 

 pared with that of a physiological salt solu- 

 tion of the same concentration, and it is quite 

 possible that such a solution exists at the 

 inner boundary of the membrane. When we 

 lead off from two intact spots on the surface 

 ■of an organ we do not notice the existence of 

 the internal potentials, since they are opposite 

 and equal; but if we destroy the membrane 

 on one spot and lead off from this spot and 

 from an intact spot of the skin the injured 

 spot must be negative to the normal spot, since 

 in reality we measure in this case the differ- 

 ence between the outer and the inner potentials 

 of the membrane. The idea that such a layer 

 exists at the internal surface has received sup- 

 port by a series of experiments by Loeb and 

 Beutner, some of which may be mentioned. 

 When we cut an apple in two and lead off with 

 salt solutions of the same kind and concentra- 

 tion from the intact outer surface and from the 

 cut, the cut is negative, as was to be expected. 

 When we remove more and more of the flesh 

 of the apple, while leaving the skin unaltered, 

 the difference of potential between outside skin 

 and cut surface at first remains unchanged; 

 but if we remove so much that the salt solu- 

 tion (with which we lead off from the cut 

 surface to the measuring instrument) reaches 

 the internal surface of the rind, the E.M.F. 

 between the intact and injured part of the 

 apple becomes less and finally disappears. In 

 this case the salt solution replaces, in our opin- 

 ion, the natural layer of liquid on the inner 

 surface of the skin. 



When we press the skin of an apple on one 

 spot with the soft part of our finger without 

 causing an abrasion of the skin, that spot be- 

 comes negative to a non-pressed spot; and yet 

 we can show that the permeability of the skin 

 is intact. This can be shown by the fact that 

 the concentration effects produced by applying 

 solutions of different concentrations are still 

 the same as in any intact part of the skin; 

 while this is no longer the case if we cause an 

 abrasion. The explanation which we ventured 

 to give for the fact that the pressed spot be- 



