ELECTRO-PHYSIOLOGY. 



579 



by the quantity of water passing any point in a given time ; similarly, 

 the quantity of electricity is the amount that flows through a cross- 

 section of the conductor in a given time. The unit of quantity is 

 the ampere." Koughly speaking, your bladder filled with urine may 

 be a volt, the ohm may be a stricture, and an ampere the passing 

 stream of urine or the unit of measure of the amount of urine pass- 

 ing through an object in a second of time. 



Electrodes. To carry the current from the different metals or 

 carbons we have wires covered with cotton, or silk, or gutta-percha, 

 which are attached to the metals or carbon; they are then called 

 electrodes. 



Polarization of Electrodes. In electrolysis of the lymph by the 

 current in a tissue there are produced positive and negative ions in 

 the lymph, which act on the electrodes. If a pair of clean platinum- 



v 



II 



Fig. 215. DuBois Nonpolarizable Electrodes. (LAHOUSSE.) 



ire electrodes have been immersed in water and have been convey- 

 ing a current for decomposition, the positive pole will, after some 

 time, become covered with bubbles of oxygen, while the negative will 

 ave collected on it hydrogen gas. If now these electrodes be sud- 

 nly disconnected with the battery and connected with a galvano- 

 eter, the needle of the galvanometer will deviate in such a way as 

 show a current in an opposite direction to the original battery 

 rrent. This is caused by the coating of the negative pole with 

 hydrogen, making it positive, and a current runs from the electrode 



Ivered with hydrogen to the electrode covered with oxygen; that 

 it runs in an opposite direction to the original current when the 

 battery was attached to the electrodes. This current will naturally 

 weaken the original battery current. This occurrence is called 

 polarization of electrodes. In the same way, if a fresh muscle or 

 none be laid across two copper wires carrying a battery current, and 

 ese be connected with a galvanometer (previously disconnecting the 



