LIVING TOKPEDOS IN BERLIN. 489 



of the skin 1 i must remain undecided. In any case, the examination 

 of dissimilarities in the skin forms an essential part of the investi- 

 gation of the organ current, and the possibility of separating these 

 two actions from each other, testifies at least to the superiority of 

 our experimental methods, for until recently the existence of any 

 action was regarded as doubtful and even denied. 



3. On Polarisation of the organ by alternating Currents. 



The most important questions in regard to the electrical organ, 

 are for the moment closely connected with its behaviour when 

 homodromous or heterodromous currents are sent through it, first 

 those which concern the polarisations which they leave behind them, 

 secondly, those which concern the apparently irreciprocal conduction 

 of the organ. Is there any relatively positive polarisation of the 

 organ, or is it nothing but the after-effect of a shock which 

 gradually loses itself in the organ current ? Does the organ con- 

 duct irreciprocally, or does only the semblance of such conduction 

 arise, owing to absolutely positive polarisation adding itself to the 

 homodromous current, whatever may be its cause and significance ? 



In order to decide the first question, I had at an earlier date 

 tetanised organ preparations, supposing that if the absolutely 

 positive polarisation were the after-effect of the shock, it must 

 appear with greater strength after a short tetanus. I made use 

 of the sliding inductorium with the ordinary arrangement, and its 

 secondary coil was pushed quite up to the primary coil, and the 

 latter filled with wires. The terminals of the secondary coil were 

 connected with the two binding screws of the switch which are 

 connected usually with the terminals of the battery circuit 2 . The 

 spring of the inductorium vibrated, and as soon as the switch 

 had opened the galvanometer circuit and closed the secondary 

 circuit, each in two places, the induced currents reached the pre- 

 paration. On the falling back of the switch, I expected very 

 strong absolutely positive polarisation in any case, but after tetan- 

 ising during 5", I obtained only feeble polarisation in a direction as 

 if opening shocks alone were present, viz. absolutely and relatively 

 positive polarisation with homodromous, absolutely positive and 

 relatively negative polarisation with heterodromous opening shocks 3 . 



1 Monatsberichte, etc., 1881, p. 1154. Archiv fur Physiologic, etc., 1882, p. 66. 



8 In Fig. 151, Plate vi. of vol. ii. part ii. of the TJntersuchungen, they are the 

 screws with which wires Sj and s 4 are connected. 



3 Comp. p. 461. Here, by a slip of the pen [corrected in the translation], the word 

 primary was used instead of-secondary. The mode of producing a tetanus of determined 



