EFFECT OF IRRITATION OF A POLARIZED NERVE. 363 



ceding investigators always employed strong currents. This autlior 

 found that the ascending polarizing current did not under all conditions 

 produce a diminution in the excitability of the nerve. The following 

 are the results of this investigator : 



P.C. I.e. 



" I. When a constant descending c\irrent is passed through the sciatic 

 nerve near the gastrocnemius, and a descending irritating current is ap- 

 plied immediately above this, I found the irritation to give a smaller 

 contraction when the constant current was passing through the nerve 

 than when this was not the case." 



Under these circumstances the muscular contractions were increased 

 during the passage of the current. 



"II. The constant descending current passes through the nerve near 

 the central end, a descending irritating current is applied to the nerve 

 nearer the muscle. The irritations seem stronger when the constant 

 current was absent." 



N. 



/ \ / \ 



I. C. P. C. 



The contractions produced by the irritation are stronger during the 

 absence of the polarizing current. 



"III. The constant ascending current passes through the nerve near 

 the muscle, while the irritation was made at a more central i^ortion. 

 During the presence of the constant current the contractions are stronger 

 than when it is absent." 



"IV. The constant ascending current is applied to the nerve near the 

 plexus, w^hilethe ascending irritating current is applied nearer the muscle. 

 During the presence of the constant current the contractions are less 

 strong than when this is removed." 



N- — ^ — * 0. 



/ \ / \. 



I. C. P. C. 



Contractions less strong during the passage of the polarizing current. 

 In conclusion Pflliger sets up the theory that the action of all irrita- 



*In these diaftTama, 'whicli are added by the author for the easier uuderatauding of 

 the views of Ptiiiger, M slauds feu- the muscle, N for the nerve, and C for its central 

 end ; I. C. and P. C. stand for irritating and polarizing current. The arrows give the 

 direction of the current. 



