452 LIVING TORPEDOS IN BERLIN. 



rurus) was always considerably stronger than the ascending (hetero- 

 dromous) in the relation of 100 to 112, 116, or even 125* I n heated 

 or dying strips the difference disappeared. This result could not 

 apparently be attributed to anything but the existence during the 

 continuance of the primary current of a positive polarisation of 

 great electromotive force, comparable to that of several Groves' 

 elements, which in the homodromous current added itself to the 

 force of the batteiy. Strips of the organ vertical to the direction 

 of the shock (therefore cut obliquely from the fish) yielded, under 

 the influence for a short time of a battery of 30 cells, a weaker 

 positive polarisation, which however was equally strong in both 

 directions ; and the strength of the polarising current gave a 

 deflection in both directions to the same number of the scale 1 .' 



So far had I arrived in 1857. How full of significance did it 

 now appear to me when in almost every experiment on the Tor- 

 pedo the superiority of the homodromous current manifested itself 

 even in a higher degree than in Malapterurus. Series 13 and 14 

 are striking instances in point, for here the homodromous current 

 of 30 Groves often appears more than twice as strong as the hetero- 

 dromous. To explain this by a positive polarisation belonging 

 only to the homodromous current, while an equal strength is 

 attributed to the negative polarisation following each current, we 

 should have to ascribe to the homodromous positive polarisation an 

 electromotive force of more than 15 Groves. In series 20, with 5 

 Groves in the circuit, the relation between the heterodromous and 

 homodromous current is at first nearly 3 to 5 ; the positive polari- 

 sation must have attained a strength of 20 Groves. In series 10, 

 with 20 Groves, the same relation is as one to three ; the secondary 

 electromotive force in this instance is indeed only equal to about 

 13 Groves, but it must have amounted to double the primary. 



When the current is directed transversely in the preparation 

 there is no difference between the two currents, and the same 

 remark holds good when the preparation is exhausted or has been 

 killed by boiling temperature (see Sect. 12, and series 17 and 18 in 

 the Appendix). In exposed preparations the difference can be ob- 

 served to diminish as the preparation gradually dies. 



We unfortunately as yet know nothing certain about the electro- 

 motive force of electrical fishes, except that it must be very 

 considerable, least so, however, in the Torpedo 2 . At all events it is 



1 Gesammelte Abhandlungen, vol. ii. p. 720. Untersuchungen, pp. 206, 218. 



2 Untersuchungen, p. 276. Anm. 2. 411. 



