132 J. F. MCCLENDON. 



is interesting to note that Overton 1 found the permeability of 

 muscle to be similar to that of plant cells. 



It might appear to the reader that the membrane theory is 

 merely wild speculation. What proof have we that on injury 

 or during contraction the muscle is more permeable to any ion? 



DuBois Reymond 2 and Hermann 3 explained the fact that living 

 muscle has a greater electric resistance than dead muscle on 

 the hypothesis that the resistance of living muscle is due to the 

 presence of membranes, which become more permeable at 

 death. They demonstrated the resistance of muscle tissue to 

 the passage of ions by the fact that electric polarization occurs 

 in muscle tissue on the pasage of an electric current. It seems 

 to me that Kodis 4 and Galeotti 5 take a step backward, in at- 

 tributing the decreased resistance of dead muscle to the liberation 

 of ions. Galeotti tried to support his view by determinations 

 of the freezing points of the living and dead muscle, but found 

 on the contrary that the change in electric conductivity of the 

 muscle did not correspond to the change in the osmotic pressure. 



Du Bois Reymond 6 observed that the electric conductivity 

 of muscle changes on (during?) contraction and Galeotti 7 found 

 it to be greater on strong contraction than on weak contraction, 

 and least on fatigue-exhaustion or cold-anaesthesia. However, 

 the duration of a contraction is momentary (about 1/5 second for 

 frog's muscle) and it is not clear that these investigators measured 

 the conductivity accurately during such a brief period, in fact 

 they probably measured it after contraction. Therefore I 

 decided to repeat these experiments, using a method by which 

 I could measure the conductivity during the actual contraction 

 period, as well as in ilic unstimulntcd condition. 8 



1 PJluger's Arch., 1902, XCII., 115. 



2 " Untersuchungen iiber thierische Elcctricitat," 1849. 



3 PJluger's Arch., 1872, V., 223, VI., 313. 



4 Am. Jour. Physiol., 1901, V., 267. 



*Zeil.f. Biol., n. f.. 1902, XXV., 289; 1903. XXVII.. 65. 



6 Loc. cit. 



' Loc. cit. 



8 McClendon, American Journal of Physiology, 1912. XXIX., 302. 



