52 PRACTICAL PHYSIOLOGY 



key to a constant battery of moderate strength 

 (Fig. 34). Throw in an ascending current, and then 

 faradize both nerves by the automatic interrupter. 

 Whilst the muscle in the one case will be tetanized 

 and speedily fatigued, in the other case the ner- 

 vous impulses will be blocked by the constant cur- 

 rent, and there will be no contraction, while on 

 removing the constant current the second muscle 

 is at once tetanized by the faradization of its nerve. 

 This experiment was devised by Bernstein to dem- 

 onstrate the fact that a nerve may be stimulated 

 indefinitely without showing fatigue i.e., without 

 its excitability and conductivity being affected. 



