LIVING TORPEDOS IN BERLIN. 439 



bottom of the tub. As a proof of the success of the operation the 

 convolution adhered to the borer. The fish twitched a good deal 

 but gave no shocks. It was taken out of the water and suspended 

 with its body in a vertical plane by means of an anatomical hook 

 thrust through the edge of the pectoral fin. Thus both the 

 ventral and dorsal surfaces could be conveniently reached by the 

 pads described on p. 430 placed horizontally. They were constantly 

 so placed that the axes of the two coincided. The galvanometer had 

 the same sensitiveness as in the experiments on Colladon's currents. 



A current showed itself with the greatest regularity in the 

 direction of the shock. It was strongest when the highest columns 

 on the median edge of the organ were between the pads, and 

 became weaker in proportion as the pads approached the thinner 

 outer edge of the organ ; e. g. if in the first case the result was 

 1 8 sc. it sank in the middle of the organ to 9 and at the edge 

 to 3 sc. It was even traceable in the same direction in the median 

 plane between the two organs, and at the edge of the body where 

 no organ exists. This is quite in order, for the persistent current 

 equalizes itself just as the momentary shock does in the skin and 

 body of the fish, by branch currents which follow every channel 

 that offers itself. In other words, if we put out of account the 

 smallness of the differences of potential, the electromotive surface of 

 the non shock giving fish differs probably from that of the same 

 fish when giving a shock only in the induction which accompanies 

 the shock. The results observed had nothing to do with the 

 wound caused by punching out the electrical convolutions. 



There was still another way of investigating the organ-current. 

 In anticipation of experiments on Torpedos I had occupied myself 

 for a long period in considering how a bundle of columns of regular 

 limits could be so obtained as to serve for experiments such as 

 those on muscle or on the organ of Malapterurus. This last is by 

 nature so limited by the outer skin and inner tendinous membrane 

 that it is easy with scissors to cut regular strips of a given length 

 and breadth, whereas in dead Torpedos, which I had once received 

 from Trieste, the prisms of the organs broke up into hour-glass 

 form 1 . I had thought of all sorts of contrivances for encountering 

 this difficulty, such as a revolving sharp borer like a trephine, with 

 which cylindrical bits of the organ might be cut out, troughs 

 of glass or ebonite, with removable sides, in which the bits could be 

 confined. When at length, last summer, I found myself in presence 

 1 Gesammelte Abhandlungen, vol. ii. p. 7 21 - * 



