XI 



ELECTRICAL FISHES 



433 



^ being opened at the same moment in which the time- 

 measuring circuit is closed at W. With the double reverser, as in 

 B, the organ-preparation is not excited, and the break shock directly 

 excites the nerve of the frog's muscle. 



The time-measuring cir- 



FIG. 273. 



cuit is therefore closed only during the period occupied by the 

 transmission and latency of excitation in the nerve and muscle, 

 since the contracting muscle opens the galvanometer circuit at H. 

 In A, on the other hand, the frog-preparation is stimulated by 

 the discharge from the organ-preparation, and the closure of the 



VOL. II 2 F 



