Electric Currents and Nerve Impulses. 59 



and the formulae for calculating these velocities are well under- 

 stood. The rate of propagation of electricity in a conductor 

 similar in form, size and material to a nerve fiber should be, ac- 

 cording to these formulae, of approximately the same order of 

 magnitude as has been measured for the rate of the nervous 

 impulse. 



The enormous reduction of velocity (about ten million times) 

 is chiefly attributable to the great ohmic resistance of the conductor 

 coupled with the electrostatic capacity. As a result of measure- 

 ments on the phrenic nerves of cats and calculations based on data 

 of microscopic sections of nerves, we have been able to construct 

 an artificial "nerve" of glass, paper, tinfoil and graphite, whose 

 total resistance and capacity are of the same order of magnitude 

 as those of the cat's nerve. On applying the break E.M.F. of an 

 induction coil to this artificial nerve and leading off to a string 

 galvanometer in the usual manner we have obtained typical 

 diphasic curves almost identical with those obtained from cat 

 nerves stimulated with the same current. Of greater significance 

 is the fact that we have been able to predict a change in the form 

 of the curves with change in the nature of the applied E.M.F. 

 and to predetermine the character of the change. As an example 

 we may mention that the action current of nerves stimulated by 

 the make or break of a constant current is of totally different form 

 when registered as a curve from the diphasic curves obtained by 

 applying a momentary E.M.F. 



It seems at present altogether probable that the phenomena of 

 electrotonus, the effects of lowering of temperature, anesthetics 

 and other well-known phenomena of nerve will be found on investi- 

 gation to be compatible with the theory that nervous phenomena 

 are essentially electrical in nature. 



