Rosearchts on the Discharge of the Electric Organ. 4:3 



interval of time may bo given. The details of the mechanism 

 were explained in § III. and illustrated in Plate V., Fig. 4. As for 

 the strength of the stimuli, care was always taken to obtain the 

 maximal discharges. Tlie sense of tlie stimulating current was 

 mainly descending, tlie distance of tlie two electrodes being about 

 o mm. This conies from the consideration that, in a descending 

 stimulus, the excitation in the nerve evoked by the closing-stimulus, 

 occurs at the cathode which is nearer to the organ than the anode 

 and therefore the excitation is evoked in an undisturbed part in the 

 nerve and propagates to the organ without any obstacle, while 

 the excitation caused by the opening-stimulus occurs at the anode 

 and it is arrested l)y the cathodic block from propagating to the 

 organ. (3n the contrary, if we use an ascending stimulus, not only 

 it has frequently been observed that the excitation due to 

 tlie closing stimulus propagates to the organ, though greatly en- 

 feebled in passing the anode; but the excitation by the opening- 

 stimulus must 1)6 affected by the stimulating current which flowed 

 before that instant. In short the result in the case of the descend- 

 ing current should be more simple. 



Returning to the problem, the influence of the flrst 

 stimulus to the second consists of two parts: namely (1) the effect 

 on the modal latent period of the second discharge, (2) the effect on 

 the height of the second discharge. The former effect almost dis- 

 appears Avhen the second stimulus departs from its predecessor 

 about one-hundredth of a second, while the latter remains a little 

 later. These may be the effects of some kind of fatigue that re- 

 covers itself in a siuall fraction of a second. We shall call the 

 phenomena the temporary fatigue. 



Oscillograms No. 74 and No. 75 (Plate XIX.) are a series of 

 experiments for such phenomena. Two stimuli, separated by 

 various intervals of time, wx^re given at a point on a nerve, and 

 the influences of the flrst stimulus on the sec(jnd discharge were 

 measured accurately. The following table shows the numliers 

 deduced from these oscillograms: — 



