xi ELECTRICAL FISHES 447 



" an after-effect of the discharge that passes into it imperceptibly," 

 and that it is due to the same, albeit much weaker disposition of 

 electromotive force, as that which provokes discharge via the 

 nerve or in direct excitation. Then, however, as was pointed out 

 by Hermann, there remains no more tangible difficulty from the 

 standpoint of his theory (in so far as this can be applied to the 

 electrical organ) than from that of du Bois-Eeymond's molecular 

 hypothesis. For the rest it appears to Biedermann that the differ- 

 ence insisted on by du Bois-Reymond between his own and Gotch's 

 view of the organ current is non-existent, since the " persistent 

 excitation " can only be interpreted as the after-effect of a previous 

 effective stimulation. 



VII. SECONDAKY ELECTROMOTIVE PHENOMENA IN ELECTRICAL 



ORGANS 



Du Bois-Reymond lays special weight upon the study of that 

 group of electromotive activities which as they appear in muscle 

 and nerve from the after-effects of artificial currents were first 

 investigated by him. While their great significance to the theory 

 of current-action cannot be doubted in the case of nerves and 

 muscles, the far more complicated structure of the electrical 

 organs renders them at first sight less appropriate to the experi- 

 mental determination of further conclusions, if we are to assume, 

 as in nerve and muscle, that every after-effect is a phenomenon, 

 partly of excitation and partly of physical polarisation. If the 

 current passing through any part of the organ has as we can 

 hardly doubt a polar action, and this in each individual plate 

 per se, and if the connective-tissue walls of partition are the seat 

 of true (negative) polarisation, it is easy to see that the prism- 

 like arrangement of these elements within any given area may, 

 and indeed must, give rise to complex positive and negative 

 effects which would be hard to unravel in any single case. 



Du Bois-Reymond thought it remarkable that the electrical 

 organ (of Malapterums) should exhibit " positive polarisation," 

 along with negative after -currents produced by true internal 

 polarisation ; the same effect was subsequently interpreted in 

 muscle as the consequence of (opening) excitation. A similar 

 relation with the physiological process of excitation was naturally 

 conjectured to exist in the electrical organ also. Before entering 



