LIVING TORPEDOS IN BERLIN. 451 



relatively positive quadrant. The first of these two swings may 

 be explained by the laws of the aperiodic movement of damped 

 magnets. As the magnet fell from a height which exceeded the 

 aperiodic district it was possible for it to pass the zero point, but 

 only once 1 . The second movement in the same direction which 

 Sachs also regarded as a swing, could only have depended on the 

 change of sign of the resulting polarisation, provided that the 

 mirror was really aperiodic. In the Gymnotus book I succeeded in 

 drawing curves of the two polarisations, by combining which the 

 resulting curves observed by Sachs could be deduced without much 

 difficulty ; but this was done under the assumption that both the 

 heterodromous and homodromous currents induce relatively positive 

 polarisation. This assumption is inconsistent with the conception 

 which has now served to account for a much more numerous and 

 better series of observations, including those of Sachs' own differently 

 arranged experiments. The only traces of heterodromous relatively 

 positive polarisation in the three electrical organs would be that 

 second overpassing of the abscissal axis in some of Sachs' experi- 

 ments. Under these circumstances I am led to believe that the 

 latter were in fact what Sachs himself considered them to be, 

 namely, oscillations. His galvanometer did not stand quite steadily 2 , 

 and perhaps his magnet was not well centred. In such a case a very 

 strong current might throw the magnet into pendular oscillation 

 to such an extent that it might overpass the zero point twice. 



However this may be, the assumption which lay at the basis of 

 my construction in the Gymnotus book, of the curves which express 

 Sachs' empirical results, cannot now be maintained, and it may be 

 considered proved that in all three electrical organs the homodro- 

 mous current induces relatively positive polarisation, if not ex- 

 clusively at any rate far more strongly. Before we attempt to 

 draw a conclusion it is desirable to take knowledge of other facts. 



11. On the relative Strengths of the Homodromous and of the 

 Heterodromous Current in the Electrical Organ. 



In my experiments on polarisation in the organ of Malapterurus 

 I had already been much struck with the different strengths of the 

 homodromous and heterodromous currents. ' In fresh strips in 

 which positive polarisation appeared in full force in the direction of 

 the shock, the descending current (homodromous in the Malapte- 



J Gesammelte Abhandlungen, vol. i. pp. 284, 324, 355. 



2 Aus den Llanos. Schilderung einer naturwissenschaftlichen Keise nach Venezuela. 

 Leipzig, 1879, p. 198. Untersuchungen, p. 137. 



G S % 



