438 LIVING TOKPEDOS IN BERLIN. 



The description will be found in the Introduction to the Treatise 

 * Ueber lodkalium Elektrolyse.' It need only be mentioned here 

 that the sheet of plate-glass measures 150 mm. long and 75 mm. 

 broad, that the upright glass tube is 150 mm. in height, the hori- 

 zontal axis bearing the corks measured from the axis of the upright 

 tube is 125 mm. in length. As I have elsewhere remarked, the 

 secondary spot is best observed when it is seen by inclining a glass 

 plate placed at a suitable angle to the horizon, and looking at it 

 from behind. In order that the iodide of potassium paper may 

 allow the spot to shine through it, a single layer of the finest 

 blotting-paper must be used. 



9. Of the Organ- current in the Torpedo. 



By organ-current I mean, in contradistinction to the shock, a 

 current persistently generated through the organ and as a rule in 

 the direction of the shock. Its electromotive force will be referred 

 to as that of the organ-current. This action of the organ which 

 reminds one of muscle tone, was first observed in the Torpedo 

 by Zantedeschi, confirmed afterwards by Matteucci and denied by 

 Eckhard. I overlooked it in Malapterurus. On the other hand 

 Robin observed it even in the imperfect electrical organ of the 

 Skate, and Sachs found it constantly in the Gymnotus 1 . 



I made a point of determining, if possible, the question as to the 

 existence of an organ-current in the Torpedo. The Torpedo used 

 in my first experiments of this kind was 36 cm. in length, and 

 had been living in the Berlin Aquarium for about five weeks from 

 the end of May. That it might be as little as possible exhausted 

 by shocks before the experiment it was killed in the following 

 manner. A sharpened borer prepared from a steel-tube 13 mm. 

 in diameter, was placed by Prof. Fritsch on that part of the bony 

 skull of the fish (which was lying tranquilly in the tub) which he 

 knew corresponded with the electrical convolution of the brain. 

 He punched out this convolution by a single stroke of the hammer, 

 which drove the borer through the thickness of the fish into the 



1 Gesammelte Abhandlungen, vol. ii. pp. 672, 718, 722, 723. Untersuchungen, 

 p. 169. As I recently discovered, Galvani in his fifth letter to Spallanzi ascribes to 

 the Torpedo a persistent electrical action, which manifested itself in the twitchings 

 of frog preparations, the feet of which he had applied to the fish. In one instance 

 the frog preparation was suspended by a silk thread. Memorie sulla elletricita 

 animale . . . al celebre Abbate Lazzaro Spallanzani, Bologna, 1797, iv. p. 75. It 

 must be remarked, however, that Galvani's statements are in some respects incompre- 

 hensible, and in others admit of a different explanation. 



