50 Art. 1.— K. Fuji: 



is not only very inaccumto, but it is doubtful wlietlierthc so-called 

 latent period measured on a graph has any definite meaning. For 

 example the theoretical curve discussed in §IV. , which has its 

 commencement at the stimulus, may give some finite value for the 

 so-called latent period, if it is measured as is usually done on the 

 experimental curve. The response in a muscle or in a nerve may 

 differ in its property from the discharge of an electric organ, though 

 I am inclined to think that the form of the negative \'ariation de- 

 pends on a similar cause to ours. As a matter of fact, the modal 

 latent period so-called by us, gives more consistent values among 

 themselves than latent periods either in our case, as always observ- 

 ed before, or in the case of the negative variation in a muscle, 

 as was shown in the paper by Lucas. Whatever it may be, he 

 said in his j^aper: " It is found that the second electric response 

 begins at a constant time after the beginning of the first, whether 

 the stimulus by which it is pro\'oked occurs immediately after the 

 end of the refractory period or considerably later. If the second 

 stimulus occurs immediately after the end of the refractory period 

 the latency of the resulting electric response may be many times 

 the normal. As the second stimulus is made later the latency of 

 the resulting response becomes proportionately less. Only when 

 the second stimulus occurs so late that it would otherwise have a 

 latency less than the normal does the second response depart from 

 its fixed time of occurrence." He also shows that the nearer the 

 second stimulus approaches the end of the refractory period, the 

 smaller the resulting response becomes. 



After this paper appeared, Gotch^ reported his analysis of a 

 similar phenemenon on the negative variation in the sciatic nerve of 

 the frog, and concluded that: "I. The electrical response of the 

 excised sciatic nerve of the frog to a second stimulus may show a 

 great increase in delay as compared Avith the response to the pre- 

 ceding stimulus. IL This increase of delay is augmented in pro- 

 portion as the second stimulus approaches the end of the period of 

 complete inexcitability (refractory period) which is developed 



* The Journal of Physiology, Vol. 40, p. 250, 1910. 



