

ON THE INTERNAL POLARISATION OF NERVES. 83 



In the Depretz signal, according to Marey 1 , magnetization 

 requires a period of ^\-^\ demagnetization T /'. As a little 

 consideration will show, the first of these numbers must be sub- 

 tracted from, and the second added to, 0-038. We may regard these 

 times as counterbalancing each other, and, this being the case, we 

 have found that the time which elapses between the opening of the 

 polarising circuit and the closing of the galvanometer circuit 

 amounts to -038 seconds with a mean variation of -005 seconds. 

 The extremes are -01 8" and O4i // . In general, therefore, we may 

 say that the time in question ranges at highest between oa // and 

 04", a variation which for my purpose must be looked upon as 

 quite immaterial. 



My investigation of the laws of internal polarisation in nerves 

 dealt mainly with the three following principal questions : 



(1) The dependence of polarisation on the strength of the polar- 



ising current. 



(2) The dependence of polarisation on the time of closure of the 



polarising current. 



(3) The durational course of polarisation. 



In the descriptions of experiments Eh. denotes the number of 

 rheochord units ; fi, the distance between the electrodes ; T, the 

 duration of closure of the current ; So, the deflection of the gal- 

 vanometer in divisions of the scale. 



1. The dependence of polarisation on the strength of the 

 polarising current. 



In each of the experiments relating to this subject I led the 

 current through the nerve for the same length of time, raising it 

 gradually from a minimum (3 Meidinger, Rh. = 100) up to a maxi- 

 mum (3 Meidinger, Rh. = 20,000), which I did so gradually that no 

 sudden alteration in the strength of polarisation could occur. The 

 strengths of current which I used were expressed in terms of the 

 number of rheochord units in the derivation-circuit, 100, 200, 300, 

 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 2500, 3000, 3500, 

 4000, 4500, 5000, 6000, 7000, 8000, 9000, 10000, 12000, 14000, 



1 Marey, La mdthode graphique dans les sciences experimentales, p. 476 ; Paris, 

 1878. 



G 2 



