130 J. F. MCCLENDON. 



in relation to the remainder of the surface. This negative 

 variation may be produced by artificially removing or altering a 

 portion of the membrane (producing the current of injury) or 

 as the result of normal stimulation, making it permeable to anions 

 (action current). 



Bernstein resorted to mathematical proof of this hypothesis. 

 We \vill not here go into details, but the gist of the matter is 

 that if the process were as we have imagined it, the electromotive 

 force of the current of injury, or action current, should be pro- 

 portional to the absolute temperature. He found this to be 

 true for temperatures between o and 18, but between 18 and 

 32 the E.M.F. was found to be too small. The muscle was not 

 permanently injured by exposure to the higher temperatures 

 for the length of time necessary for the experiments. Bernstein 

 explained this discrepancy by the further assumption that at the 

 higher temperatures the plasma membrane became slightly 

 more permeable to anions. 1 



Since the muscle contains a higher per cent, of potassium than 

 the blood plasma or lymph, it might be supposed that K ions 

 passed outward through the plasma membrane and gave the 

 surface of the muscle element the positive charge. But if this 

 were the case, the current of injury should be reversed by placing 

 the muscle in a solution containing potassium in greater concen- 

 tration than in the muscle. This reversal, how r ever, was shown 

 by Hober not to occur. Since lactic and carbonic acids are pro- 

 duced by muscle and diffuse out in increased amount on contrac- 

 tion, one might suppose H ions to give the muscle surface the 

 positive charge. This is only a guess (and a poor one, since un- 

 dissociated molecules of COz and lactic acid are lipoid-soluble) 

 but may be convenient until some better one is proposed. Per- 

 haps the carbonic acid combines with amphoteric proteids, which 



1 This is similar to the conclusion reached by Biataszewicz, Bull. d. I' A cad. d' 

 Sc. d. Cracovie, Sc. Math. e. Nat., Oct., 1908, p. 783, in regard to the unfertilized 

 frog's egg. In order to explain his observation that the rate of swelling in tap 

 water increased 5 times for every 10 rise in temperature, he assumed that heat 

 increased the permeability to H-^O. This would seem to be the simplest explana- 

 tion, provided the swelling were not due to chemical production of osmotic sub- 

 stances: and since the A of the ripe ovarian egg is .48 but is reduced to .045 after 

 oviposition, Biochem: Zeit., 1909, XXII., 390, much if not all of the swelling is 

 probably due to the initial osmotic pressure of the egg interior. 



