INTRODUCTION. 97 



Indeed, I can communicate several experiments which I performed 

 in the summer session of 1882, in conjunction with Fraulein L. 

 Nemerowsky, and which appear to me to confirm Hermann's 

 assertion that internal compensation is the less conceivable the 

 nearer one gets to the proper electro-motive surface. As is set 

 forth in Fraulein Nemerowsky 's dissertation 1 , we have investigated 

 the strength of the nerve-current, that is to say its electro-motive 

 force, according as the electrodes, of which the one was always at 

 the cross-section, were more or less separated from one another. If 

 the electrodes are placed as near as possible, the electro-motive force 

 of the current led off into the galvanometer is very small. It 

 increases with the distance between the electrodes, and finally 

 reaches a maximum when the electrodes are 5 to 7 mm. apart. 

 With a yet greater separation of the electrodes it diminishes again, 

 evidently because currents of opposite direction (ascending) now 

 begin to be included 2 , which diminish the strength of the descending 

 current. If now, with a separation of electrodes of 5 to 7 mm., by 

 far the greatest amount of current is led off by the external cir- 

 cuit, it is intelligible that in these circumstances the nerve-current 

 will be most affected by over-compensation, since the electrodes, 

 so to speak, include most current, and the lines of flow of the 

 two currents differ from one another least. We have found as 

 a fact that, since with electrodes close together it is impossible 

 to abolish or weaken the nerve-current even by means of strong 

 counter-currents, no hiatus appears, but the contractions first 

 appear with much stronger exciting currents. The hiatus, how- 

 ever, is most marked when the nerve-currents are most influenced 

 by over-compensation, that is, with a separation of electrodes of 

 5 to 7 mm. 



By these explanations I believe that I have satisfied those who 

 took exception to my theory of the hiatus 3 . 



As already mentioned above, I had, in studying with Moschner 

 the phenomenon of the hiatus, opened and closed only in the main 

 circuit. If a compensator (du Bois-Reymond's straight compen- 

 sator) is used for regulating the strength of the exciting current, 



1 Tiber das Phanomen der Lucke, by L. Nemerowsky. Inaugural dissertation, 

 Berne, 1883. 



2 See my paper on the above subject, Pfluger's Archiv, xxviii. p. 140. 



3 See also Biedermann (Wiener Sitzungsberichte, Ixxxv. Abth. 3. p. 160), who 

 has arrived at similar results in the case of muscle as ours in that of nerve, and has 

 drawn similar conclusions. 



