15 



current (1) with the positive pole on the living bit of nerve, 

 and (2) with the negative pole on the living bit of nerve, and 

 record your results on the subjoined table : 



B. On Nerve and Muscle through the Skin. 



Arrange the wires to use the current from the terminals G T 

 and introduce a commutator to change the direction of the 

 current when desired (figs. 8 and 9). Put some saturated salt 

 solution in a basin and fix the end of one wire in the solution. 

 To the end of the other wire attach a flat zinc electrode, 

 placing a bit of chamois leather saturated with the salt solution 

 between the electrode and the skin. Dip the fingers of the 

 left hand into the salt solution and apply the flat electrode 

 over the back of the thenar muscles. 



DuK of 

 Sol" 



Com m uiaior Flat 



FIG. 8. Electrical Stimulation of Muscle through Skin. 



First use the cathode. Beginning with a strong current, 

 record the results which follow making and breaking the 

 current. Then, by moving the handle on the switch-board 

 from S. to W., reduce the strength of the current, and again 



