EFFECT OF IRRITATION OF A POLARIZED NERVE. 



399 



111 illustration of the fact that the strength of the irritating current 

 influences the effect of the polarizing current on the excitability of nerves 

 vide experiments 12, 13, 14, 16, 22, 26, 28, 43, 127, &c. 



May not the extent of muscular contractions produced by the irrita- 

 tion of a polarized nerve be largely due to the x>roportion between the 

 strengths of the two currents ? 



In the first experiments made in answer to this question the irritations 

 were made by means of an induction apj)aratus, the non-polarizable 

 electrodes being, however, still adhered to. The polarizing current, 

 whose strength was never changed, was produced by a single Leclanche 

 cell. In these experiments I found that when the strength of irritation 

 j)roduced a minimal contraction — no weight being attached to the myo- 

 graph — both the ascending and descending polarizing current produced 

 an increased irritability of the nerve to the side of the anode as well as 

 to the side of the kathode. With a somewhat stronger induction cur- 

 rent, or, what amounted to the same thing, by attaching a weight to the 

 myograph, and then observing the minimal contractions, the results of 

 Pfluger were obtained ; that the jjolarizing current produced an in- 

 creased excitability of the nerve to the side of the kathode and a decreased 

 excitability to the side of the anode. By still further increasing the 

 strength of the irritation the results of Eckhard were obtained — a de- 

 creased excitability of the nerve to the side of the kathode as well as to 

 the side of the anode. 



Illustrative experiments. 



