NOTES AND ADDITIONS. 



305 



the curve is drawn downward from the time-line o . . . o . . . t, 

 to indicate that the direction of this induced current is 

 opposed to the direction of the primary current. If the 

 primary current is interrupted, it suddenly falls from the 



fv, 



strength /, as indicated by the straight line 1. With this 

 fall corresponds an inductive current, which suddenly rises 

 very abruptly and again falls somewhat le^s abruptly, as 

 shown in curve 2. From this it is evident that the latter 

 must be physiologically much more effective than the former. 



