MUSCLES, NERVES, AND ELECTRICAL ORGANS. 221 



This does not agree well with the idea that we have here to do with 

 ordinary internal polarisation. That this maximum points to an 

 increase of positive polarisation which appears at this time is the 

 more difficult to admit, inasmuch as the maximum appears rather to 

 be coincident with the destruction of polarisability by prolonged 

 action of very strong currents (Sect. n). 



The help which the comparison of the negative polarisation of 

 muscles, nerves, and electrical organs with ordinary internal polari- 

 sation gives in explaining it, is entirely wanting as regards positive 

 polarisation. If negative polarisation could be identified with ordi- 

 nary internal polarisation, it would be covered by the physical process 

 in the hypothetical septa referred to in Sect. 3. Of the occurrence of 

 negative and positive polarisation in the same electrodes there is only 

 one example observed by me, viz. that of iron, and zinc containing iron 

 in a solution of zinc sulphate 1 . Although this double polarisation 

 depends on the time of closing and opening, in the same way as that 

 with which we are now occupied, we can scarcely have recourse to 

 it for an explanation. In order to refer the polarisation of muscles 

 and nerves and electrical organs to known physical facts, it is there- 

 fore necessary to assume another frequently recurring discontinuity 

 in the direction of the current, which, like the surfaces of certain 

 electrolytes, would be the seat of a positive polarisation 2 . If such 

 a discontinuity could be assumed in muscle, or even in nerve, it 

 would still be entirely wanting in the electrical plates of the malap- 

 terurus. It would also be very hazardous to suppose the existence 

 in three such different structures of any such alternation of materials 

 as could produce secondary electromotive actions. Besides, the 

 positive polarisation in the electrical organs is much too strong to 

 be thus explained. 



In addition to this there is the peculiar manner in which positive 

 polarisation depends on current density, and on times of closure or 

 opening. Without reference to the maximum in prolonged time of 

 closure, the dependence of negative polarisation on these conditions 

 is at all events similar in form to that of the internal polarisation of 

 moist porous bodies. This is not the case with positive polarisation, 

 in respect of which there is a liminal intensity of the current density, 

 below which it does not appear at all. It then appears suddenly with 

 a force which increases indeed with current density, but slightly if 

 at all with the time of closure. The limen lies higher for the electrical 



1 Gesammelte Abhandlungen, vol. i. pp. 57-60. 



2 Ibid. vol. i. p. 6. 



