PRODUCED BY A CONSTANT CURRENT. 11 



while its influence increases for every stimulus applied on the 

 far side. 



2. That at seats of stimulation lying- far up, an approximation of 

 the polarising- current to the muscle is accompanied, first by a 

 diminution, then by an increase of influence on the excitability. 



3. That with strong polarising- currents inhibition takes place 

 at the negative pole ; and if the excitatory effect has to pass this 

 pole in the course of its propagation, muscular contraction must fail, 

 and this as well with an ascending current and extrapolar stimula- 

 tion as with a descending current and intrapolar stimulation. The 

 last case should furnish a real experimentum crucis against Pfliiger's 

 view. With the first two it is not so, as other circumstances 

 might influence the result, although such phenomena cannot be 

 foreseen on Pfliiger's theory. 



The experiments instituted in proof of (i) were completely 

 successful. When the fixed system of electrodes was brought 

 nearer to the muscle, it appeared that with an ascending current 

 the katelectrotonic increase of contraction became greater and its 

 anelectrotonic diminution less, as also that with a descending 

 current the relation was reversed. 



With intrapolar stimulation Hermann found occasionally at the 

 upper seat of stimulation a diminution, and at the lower an increase 

 of muscular contraction. This, which would certainly form a 

 decisive proof against Pfliiger's theory, may however be explained 

 on the ground that we have to deal with the same sources of error 

 as in the experiments previously referred to, namely with the 

 presence of newe branches to the thigh, whereby, in the more 

 distant position of the system of electrodes, the real indifference- 

 point came closer to the proximal electrode than it did when the 

 system of electrodes was brought nearer to the muscle. 



In proof of (2) Hermann did not arrive at definite results. On 

 the other hand, in the experiments which he instituted to obtain 

 proofs of (3) he found, quite correctly, that with strong currents 

 the muscular contractions fell off, and were entirely annulled when 

 the excitation had to pass the negative pole. With an ascending 

 current this could be explained on Pfliiger's theory by inhibition 

 at the positive pole, but this theory could not possibly explain 

 why the influence of a stimulus applied in the neighbourhood of 

 the "negative pole should be diminished or annulled by a de- 

 scending current. 



Besides this it was only with currents of moderate strength that 



