THE LEAF CONSIDERED AS AN ELECTRIC ORGAN 243 



very great Is the activity something specific occurring in 

 these fishes alone, and unrelated to other electro-motive 

 phenomena in the animal tissues? Or is it related to the 

 electromotive action already observed in excited muscles ? 

 In support of the latter view, it is urged that most of the 

 electrical organs consist of modified neuro-muscular elements. 

 Against this argument, however, as we have just seen, is the 

 instance of Malepterurus, in which, from a morphological 

 standpoint, the organ is to be regarded as a modified gland, 

 and therefore not muscular in character. 



There are certain peculiarities, further, about the action 

 of these organs which call for elucidation. Among these 

 is the question of the character of the natural current of rest, 

 about the significance of which there have been differences 

 of opinion. There is also the fact that the organ, under a 

 single strong excitation, gives rise not to one, but to a series 

 of electrical responses. 



We have seen that the apparently unique character of 

 this group of organs constitutes an added difficulty in 

 arriving at a correct theory on the subject. But it is clear 

 that if we could succeed in discovering among vegetable 

 organs any cases which showed similar characteristics, 

 we should then be so much the nearer to the determination 

 of that fundamental reaction on which the phenomenon in 

 animal and vegetable alike depends. 



In the typical case of Torpedo, it has been seen that the 

 conducting nerve, when entering into an electrical plate, 

 breaks into an extensive ramification, and thus forms the 

 nervous surface, in contradistinction to the jelly-like sub- 

 stance in which it is imbedded, forming the opposite, and 

 here indifferent surface of the plate. Now this arrangement 

 is closely imitated by many ordinary leaves, in which the 

 vascular elements break, on reaching the lamina, into a pro- 

 fuse arborisation. 



I must here anticipate matters to say that I have discovered 

 in the fibro-vascular bundles of plants (see Chap. XXXII.) 

 elements which are in every way analogous to the nerves of 



R 3 



