PHENOMENA OF MUSCLE AND NERVE. 287 



Reymond must have thought of it, and he was then bound to 

 investigate to what extent it was connected with the phenomenon 

 discovered by himself, even if there had been some reasons for 

 assuming that it was not by itself a sufficient explanation of the 

 facts ; but, as will be seen, such reasons are not forthcoming. In- 

 stead of this, such an explanation is not once mentioned, simply 

 because the molecular theory has again asserted its power of 

 paralysing the next step forwards. 



Let us next see how the indications of this action-current should 

 present themselves. When the indifference-point is in the middle, 

 then, after break, the anodic half of the intrapolar region, if ap- 

 propriately led off, would show an action-current in the same 

 direction as the polarising current ; this must also be the case when 

 one leading-ofF electrode is in the kathodic, the other in the anodic 

 half ; on the other hand, if both leading-off electrodes were situated 

 in the kathodic half, the current would be absent ; but it is con- 

 ceivable that, owing to electrotonic spread of the anodic action- 

 current, it might be present even in this last case. With strong 

 currents the + after-current should be found throughout the intra- 

 polar region. 



This current thus comes in conflict with Peltier's polarisation 

 after-current in the intrapolar region. But it is essential to polari- 

 sation after-currents, first that they become stronger, the longer 

 within certain limits the polarising current has been closed ; and, 

 secondly, that they rapidly decrease after the break of the latter. 

 The most favourable condition for the development of the action- 

 current (' positive polarisation ' of du Bois) is above all very short 

 closure of polarising current, so that the maximum of polarisation is 

 not obtained with such closure ; but even under such conditions, 

 during the first moment after break, the polarisation effect is 

 stronger than the + action-current, and the after-current is there- 

 fore diphasic. The chief facts can be thus thoroughly and simply 

 explained without taking into account certain new phenomena to 

 be presently referred to. 



The next step, necessary to prove the validity of this explanation, 

 is to investigate the influence which the position in the intrapolar 

 region of the leading-off electrodes exerts on both and + after- 

 effects ; a problem which du Bois-Reymond has not investigated. 



Two pairs of leading-off electrodes were brought into contact 

 with the intrapolar region, and each pair connected with the circuit 

 of a separate galvanometer and compensator. 



