488 LIVING TORPEDOS IN BERLIN. 



touched the clay. It should be mentioned that in these experiments 

 the skin was no longer fresh, and might have suffered by dryness 

 as well as from frequent handling of the fish. The result how- 

 ever, in conjunction with the other reasons, tells strongly against 

 independent electromotive action of the skin. 



Experiments like those by which I determined the electromotive 

 action of the skin of the frog 1 would be necessary, in order to decide 

 between the second and third hypotheses. Unfortunately, there are 

 here great difficulties. The detachment of sufficiently large pieces 

 of uninjured skin, which is facilitated in the frog by the lymph 

 spaces lying underneath the skin, can scarcely be carried out in the 

 torpedo. I tried therefore to observe currents in the two first 

 winter fishes (V and VI), by placing on them, not simultaneously, 

 pads soaked in solution of sodium chloride. In the frog and other 

 naked amphibia, a strong current is always obtained in this way 

 from the more recent to the earlier points of contact, because by the 

 caustic action on the skin, the electromotive force, the direction of 

 which is from the exterior to the interior, is diminished, or even 

 annihilated. I made the experiments on the tail of the Torpedo, 

 having amputated it high up along with a piece of the vertebral 

 column and a slice of the body. Naturally, cm-rents were not 

 wanting, but they had sometimes one, sometimes the other direction, 

 and more often, they did not disappear on a prolonged application 

 of the pads, so that no importance can be attached to them ; all the 

 less because there was a danger of illusive effects, partly arising 

 from the interior of the preparation, partly from the neighbouring 

 cut surfaces. A comparison of the strengths of the currents with 

 those in the frog would have had no meaning ; measurements of force 

 are precluded by the transitoriness of the actions. 



The whole matter is not very important, and has hardly any 

 relation to the electromotive property of the organ of the Torpedo 

 and of the Gymnotus. It is much rather to be supposed that in 

 other fishes also, the skin is feebly positive to internal parts 

 which are without electromotive action. In them, however, parts 

 are wanting, which, like the organ preparations, consist only of 

 skin and a tissue which is inactive or possesses only feeble electro- 

 motive action, in accordance with known laws. Whether the 

 observed positivity of the skin in the Malapterurus may possibly 

 contribute anything in support of Prof. Fritsch's hypothesis, accord- 

 ing to which, the organ of this fish has its origin in the mucus cells 

 1 Untersuchungen, loc. cit. 



