514 ANNALS NEW YORK ACADEMY OF SCIENCES 



Plate 4 



A. Middle record: response of an isolated column (Torpedo organ) to an elec- 

 trical stimulus directed along its main axis. 



Ivower : response of a small fragment of tissue ; transverse stimulation ; thresh- 

 old intensity. 



Upper: single fiber action potential (electric organ nerve). 

 Time scales in milliseconds. 



B. Double beam oscillograph record. 



Above: discharge of a fragment of electric tissue (Raia). 



Below: impedance change test with an alternating ciuTent of 15,000 cycles. 



The whole activity wave lasts 12 milliseconds. 



