132 



mostly 5 — 8 in rminhei- with an interval of 5<7. Fig. 1 represents 

 one snoli discliarge, where the shocks came with an interval of 

 5,6^7. Crkmick fonnd an average of 5,6 a in reflex-discharge. Most 

 striking in these rhythmical discharges is the regnlarily and the 

 eqnal amplitnde of the single shocks, as appears clearly from my 

 tignre. In the periodical discharges after stimnlation of the nei've 

 of the excised organ, 1 never obtained snch regnlarity and as a rnle 

 ineqnal amplitnde. Usually the shocks diminish gradually, sometimes 

 they first incr-ease, then decrease. Fig. 6a and 5/^ illnstiate this more 

 (clearly. The periodical discharges in reflex-action therefore give the 

 impre.ssion of being caused by a series of centi-al impulses from my 

 nervous system, whereas the periodical discharges after stimulation 

 of the organ or the nerve seem to be due to secondary self-stimu- 

 lation. This is especially and to a grealei- extent true in the case 

 of the stimulation of the nerve. After direct stimnlation of the organ 

 usually only two small, secondary discliaiges occur, provided that 

 the nerve has been cut at the vei-y spot of its entrance into the 

 organ. Fuji however has registered reflex-discharges (in Astrape 

 japonica) in which only two shocks occurred in every group 

 followed by a small one. The same result was also obtained after 

 stimulation of the nerve stem. For this reason Fuji believes that 

 the successive discharges occur by self-stimulation. The solution of 

 this question has impoi'tance for the question which has been solved 

 by Garten ^) in Malaptei-urus, i. e. in how far the discharges of 

 both organs occur simultaneously. 



In a detailed lesearch Bernstein and Tscherm.\k ') have tried to 

 find out whether the current which the electrical organ produces 

 during activity is caused by a concentration-chain or whether a so- 

 called chemical chain here causes the difference in potential. To 

 solve this question the temperature-coefficient of the force of the 

 current in the organ was investigated within certain limits of tem- 

 perature. 



From theoretical considerations it is known, that in a concen- 

 tration-chain the E. M. F. is nearly proportional to the absolute 

 temperature. Bernstein already had found a positive temperature- 

 coefficient for the current in muscles and nerves and within normal 

 limits of temperature the E. M. .F. proved to be nearly proportional 

 to the absolute temperature. 



In their study on the electrical organ the authors mentioned above 



1) Garten. Zeitschr. f. Biol. 1910. Bd. 54. S. 399—430. 



*) Bernstein und Tschermak. Pfliigers Archiv. 1906, p. 112. 



