506 LIVING TORPEDOS IN BERLIN. 



was pushed quite over the primary coil filled with wires. The 

 distance of the bobbin (5000 turns) was 10 cm. from the mirror. 



In Fig-. 20 the curves denote the circuit, including the secondary 

 and galvanometer coil. The preparation was taken from the fifth 

 fish, killed the previous day; the organ current force amounted at 

 first to + 0-0072. 



When the clay points were in position (i), I obtained 



| 42 | 12 | 42 | 15 sc.; 

 in position (2), 



t 38 I 19 t 38 t 20sc -; 

 finally, in position (3), 



| 40 | 22 | 40 | 22 SC. 



According- to this, there can be no doubt, that irreciprocal con- 

 duction, whatever may be its cause, has nothing to do with the 



skin ; this was indeed already 

 ,, proved when I first observed 



it in the malapterurus prepar- 

 ations, where the skin consti- 

 tuted only an external closure. 

 It might however still be 

 supposed that its seat is super- 

 ficial, that it depends on a resist- 

 ance which develops itself 

 Fig. 20. n ly a ^ the contacts of the clay 



points with the lateral surfaces 



of the preparation, after the manner of external secondary resistance. 

 At first sight this is very improbable, considering that it increases 

 evidently with current density, not with current strength ; that it is 

 observed even with such transient shocks as the opening shocks of 

 an induction apparatus ; that the interposal of the skin makes 

 no change in its mode of appearance ; and finally, that if one of the 

 clay points, the positive or the negative, were the seat of a special 

 resistance, this must be the case for homodromous currents just as 

 much as for heterodromous. 



But this conception would be quite impossible, if it were shown 

 that the irreciprocity increases with the length of the columnar 

 tract traversed by the currents. Now this is in point of fact the 

 case. 



A long tract of organ (4) gave 



f 32 I is | 3 3 4 13 sc.; 



