126 PHYSICAL CHEMISTRY 



dead muscle. Perhaps the perimysium surrounding the muscle, 

 being formed of electronegative colloids, is more permeable to 

 the cations than to the anions of the electrolytes between the 

 muscle fibers, hence the dilute side (in reference to the salt) is 

 positive. When the end of a muscle is dipped in water, the 

 dilute (water) side is positive until the water injures the muscle, 

 when the dilute side becomes negative, the perimysium emf being 

 superseded by the current of injury. Briinings found that when 

 the entire body of a man, a frog or a plant is used as a mem- 

 brane in a concentration cell, the dilute side is positive. 



Loeb and Beutner (1914), who extended Briinings's experi- 

 ments, oppose all hypotheses on the origin of animal electricity 

 which relate to membrane destruction or selective permeability 

 to ions. They admit, however, that a current of injury is pro- 

 duced by cutting off part of the skin of an apple, and that the 

 same increase in permeability may be produced by merely press- 

 ing the skin with the finger. The argument they bring against 

 Bernstein's hypothesis is the similarity between living tissue on 

 the one hand and Beutner's acid membranes or lecithin in guaicol 

 on the other, when used as membranes in certain concentration 

 cells. It seems perhaps more significant that in a previous paper 

 (1912) they interpret their results as showing that the seat of 

 the current of injury is the intact membrane and that it is caused 

 by the increase in permeability or removal of the membrane 

 at the injury. 



Having thus sketched the membrane hypothesis, it may be ad- 

 visable to add additional proofs of its validity. If the membrane 

 theory is correct, change of temperature of the cut end of a 

 muscle should not affect the current of injury since the cut end 

 is not the seat of the emf, but the current of injury should be 

 proportional to the temperature of the intact end. From Nernst's 



Ci 



formula emf (in millivolts) = .198 T log , where T is the 



c 2 

 absolute temperature, hence any change in T would cause a 

 corresponding change in the emf. Bernstein ("Elektrobiologie," 

 p. 97) found this to be the case, at least between the tempera- 

 tures i8°-o°. In case two points on an intact muscle are at 

 different temperatures Nernst's formula becomes emf = .198 T 1 



