The Demarcation Current of Mammalian Nerve. :\~1\ 



(2) 0-6 x 1-059 = 0-6354 



(3) 0-75x0-921 = 0-69075-| 



Which relationship can be interpreted to mean that for a consider- 

 able range of concentrations the E.M.F. "recovered" varies almost 

 exactly inversely as the concentration, and outside this range the 

 deviation from the Jaw is not great. 



The value of the constant, which is practically 0'70, is evidently the 

 concentration of a saline solution in which the E.M.F. should be 

 unaltered by the immersion. 



The preservation of a constant temperature throughout the series of 

 experiments is of importance, the variation with temperature being 

 considerable, and complicated. Data are given from a few experi- 

 ments made to determine the interest of this point. 



The data are as before, each from a separate experiment upon a 

 measured length (5 cms.) of the sciatic nerve of a cat ; the only 

 difference being in fact that the temperatures of the solutions were 

 varied instead of their concentrations. 



Temperature 

 of solution. 



9C. 

 17 



28 



38 

 * 



9C. 



17 



27 



34 



2 



Concentration 

 of solution. 



75 per cent. NaCl. 



3-0 per cent, NaCl. 



E.M.F. " recovered " in 



terms of the original 



as unity. 



1-01 



0-92 

 0-62 



0-62 

 * 



0-25 

 0-24 

 0-11 

 0-04 

 0-15 



It may seem an obvious and foregone conclusion that the isotonic 

 solution, in which the nerve may lie with the minimal disturbance 

 due to the transference of water and salts, should closely coincide 

 with the solution in which the E.M.F. is retained constant, and 

 also with the probable isotonicity of the solution which in the living 

 body bathed the outer surface of the nerve. 



It may indeed be maintained that from the point of view of the 

 established hypothesis the local short circuiting of the demarcation 

 source would be affected by solutions varying in concentration from 



