59 o THE PHYSIOLOGY OF ELECTRICAL ORGANS. 



electrical fish to their own discharges is only relative. It seems far 

 more likely that the discharges, if forcible or prolonged, exercise deleterious 

 effects upon both central and peripheral parts of the nervous system. 

 In confirmation of this is the observation of Schonlein and others, that 

 after repeated reflex discharges of a violent character, the excised organ 

 is in a far lower state of excitability than it is when repeatedly excited 

 by stimulation of its nerves. 1 



The Nature of the Activity of Electrical Organs. 



A few remarks may be made, in concluding the present article, with refer- 

 ence to the question as to how far the activity of electrical organs is to be 

 regarded as based upon changes which are sui generis, rather than upon those 

 present in other excitable structures such as muscle and nerve. The great 

 electromotive force of the change is, at first sight, only to be accounted for on 

 the supposition that the organ is the seat of special processes unlike those present 

 in muscle or nerve ; it has, however, been insisted upon in this article, that 

 the extent of this electromotive force is due to the disposition of the elements 

 in series, and that in each element of the series no such enormous development 

 occurs. The columnar structure of the electrical organ thus modifies rather 

 than determines the characteristics of the activity. The separate elements 

 constituting the essential structural features of the organ, have in the case of 

 Torpedo, Mormyrus, Rata, and Gymnotus been developed from neuro-muscular 

 elements, and whereas the nervous part persists, the muscular part has been 

 transformed. It is thus not unreasonable to consider, in the first place, how 

 far the activity of the organ can be viewed as in its essence of the same 

 nature as that which produces the electromotive changes accompanying 

 muscular activity. Although there is no disparity between the electromotive 

 force of the change in an organ element and that of such a muscle as the 

 sartorius, there are very serious objections to any causal connection between 

 organ and muscular electrical effects. In Malapterurus the morphological 

 evidence tends to show that glandular elements have been utilised in the evolu- 

 tion of the organ, not muscular ones. Further, the multinucleated protoplasm 

 which constitutes the greater part of the disc of Raia and the whole of the 

 Malapterurus disc is homologous neither with muscle nor with gland, but with 

 the protoplasmic sole of the nerve end-plate. The whole question, therefore, is 

 narrowed down to the two following possibilities: — (1) Is the disc the 

 effective part of the organ element ? If so, then the change, though analogous 

 with that presumably present in nerve end-plates, is in reality something 

 sui generis, for no electrical effect has been observed in such end-plates. (2) 

 Is the disc merely a means for reinforcing electrical changes occurring in the 

 nerves themselves? If so, then the effective part of the organ-elements is 

 nervous, and the change is based upon the same processes as are present in 

 nerve when roused to activity. (1) The view that the disc is an excitable struc- 

 ture responding to nervous impulses which reach it through its nerves, is con- 

 tradicted by all experimental observations. Drugs, such as curari and atropin, 

 appear to have no specific paralysing effect upon the organ, unless such doses 

 are employed that the nerves themselves are affected. There is no evidence 

 that the discs can be excited apart from their contained nerves; all agents 

 which annul the excitability of the electrical nerves annul at the same time 

 the response of the organ to electrical currents which traverse its substance. 

 One of the most suggestive facts bearing on this point is the complete inex- 

 citability of an organ when deprived of its nerves through nerve degeneration 

 in consequence of previous section. Direct excitation of the organ is direct only 

 in appearance, not in reality ; there is always nerve excitation, whether the 



1 Schonlein, loc. cit. 



