158 PHYSIOLOGY OF MUSCLES AND NERVES. 



plants — that which, flashing amid the roar of thunder, 

 illuminates the wide canopy of heaven — which binds 

 iron to iron, and directs the silent recurring course of 

 the magnetic needle all, like the varied hues of the 

 refracted ray of light, flow from one common source, 

 and all blend together into one eternal all-pervading 

 power/ 



3. All electric fishes are distinguished by 'the pos- 

 session of peculiar organs in which the electric discharge 

 originates. These resemble powerful batteries, which 

 can be put in action by the will of the animal, and 

 which then generate currents which, passing through 

 the water, meet and act upon other animals which 

 happen to be near, so that the latter may even be 

 thus killed. These electric organs, as they are called, 

 are formed on the same plan in all the three above-men- 

 tioned genera of fishes. They consist of a large number 

 of minute and delicate plates which, arranged side by 

 side and enclosed in coverings of connective tissue, 

 form the whole organ. In the Torpedo these organs 

 lie flat on either side of the vertebral column. In the 

 Gymnotus and the Malajjterurus they are arranged 

 longitudinally ; and in the latter they form a closed 

 tube, in which the animal is concealed, its head and 

 tail, as it were, alone projecting. The separate plates 

 of which the organ consists are arranged, therefore, 

 horizontally in the Torpedo, vertically in the G'^/wnofi^s 

 and Malapterurus. Each of these plates consists of 

 an extremelv delicate membrane which, when the organ 

 is in a state of activity, exhibits positive electricity on the 

 one side, negative on the other. The currents of the 

 numerous plates combine as in a battery, and thus all 

 together afford a very powerful current. With each 



