STIMULATION OF MUSCLE AND NERVE 117 



of an inductorium (Fig. 30). Arrange the pri- 

 mary for single induction shocks, which must 

 not be maximal. Turn the pole-changer to bring 

 the cathode next the metal electrodes. Using a 

 weak induction current as stimulus, record on a 

 stationary drum three contractions: (1) before 

 the passing of the galvanic current through 

 the nerve, (2) during its passage, (3) after its 

 passage. 



The second contraction that obtained by 

 stimulating in the cathodal region during the 

 passage of the galvanic current will be greater 

 than the other two. 



Eeverse the galvanic current and repeat the 

 experiment, the stimulation now being in the 

 anodal region. 



The stimulation in the anodal region during 

 the passage of the galvanic current causes less 

 than the normal contraction. 



2. The stimulating current may be superposed 

 directly on the polarizing current by using the 

 same electrodes. 



Connect a dry cell through an open key with 

 the and 1 metre posts of the rheochord 

 (Fig. 31). Connect the positive post of the 

 rheochord with one of the non-polarizable elec- 

 trodes. Join the slider to one end of the second- 

 ary wire of an inductorium; to the other end 



