II. THE USE OF ELECTRICITY FOR STIMULATING 

 IN PHYSIOLOGY AND MEDICINE. 1 



(The Student must revise his knowledge of Electricity.) 



Stimulation of the Nerve-endings in the Skin 

 as determined by Sensation. 



METHODS. A. Simple Galvanic Current. Connect thick 

 covered wires with the terminals marked G on the table, + for 

 positive (anode) and for negative (cathode), from the 

 constant current supplied from a generator. Insert into the 

 circuit a mercury key, as shown in the diagram, so that when 

 it is closed the current will flow through the terminals 

 (fig. 1). Hold the ends of the wires, one on each side of the 

 tongue, and note the sensations produced when the current 



Electrocles 



Mercury Key 



FIG. 1. Simple Galvanic Current. 



is allowed to pass (made) by closing the key, when it is cut 

 out (broken) by opening the key, and when the current is 

 flowing. Note whether the sensations are different or similar 

 at the two poles on closing and on opening. and during the flow. 



RESULTS. Taking sensation as the index of stimulation, 

 record on the table below the results of the sudden making 



1 The current is supplied from a generator giving from 15 to 30 volts 

 to the switchboards on the tables. The terminals marked G are for 

 galvanic stimulation, and give from to 400 milliamperes. The ter- 

 minals marked F are for Faradic stimulation, and give about 1-5 amperes. 

 The terminals marked T are connected with a chronograph and inter- 

 rupt at 1 sec., 0-1 sec., or 0-01 sec., according to the way in which the 

 instrument is set. 



