LIVING TOEPEDOS IN BERLIN. 487 



in the case of the torpedo, 



Physiological Clay | Organ + Organ | Skin + Skin wetted with sea water | Glay, 



and in the case of the malapterurus, 



White of egg | Organ + Organ | Skin + Skin wetted with river water | White of egg. 



It may seem surprising- that the interposition of sea water, and 

 still more of white of egg with alkaline reaction, instead of the clay 

 kneaded up with physiological solution of chloride of sodium, does 

 not cause a more considerable difference of action. In order to 

 judge certainly as to this, it would be necessary to study first the 

 chemical reaction of the torpedo's skin, and also to make experi- 

 ments with conducting liquids of a more decided electro-chemical 

 character. 



The third hypothesis is, that the skin possesses its own inde- 

 pendent electromotive action, like the skin of the naked amphibia, 

 according to my discovery *. This assumption has also much against 

 it. In the first place, the direction of the force would be the 

 opposite, inasmuch as the action of the skin is from without inwards 

 in the amphibia. Secondly, it would be more than eleven times less 

 than in the case just mentioned, where the skin current force is 

 found to be comparable to that of muscle and nerve 2 . Thirdly, up 

 to the present time, skin currents have been observed in none of 

 the fishes investigated, including those without scales, like the eel 3 . 

 Fourthly, the electromotive activity of the skin seemed to me to 

 outlast that of the organ in the torpedo, and this would be more in 

 accordance with a liquid battery. Fifthly, I did not succeed in 

 observing an electromotive action of determined direction and 

 amount between the external and internal surfaces of a detached 

 piece of skin. I employed the same method in these experiments 

 as Rosen thai for the skin of the frog 4 . I made openings with the 

 punch in two mica plates laid one over the other, placed the skin 

 between them, and pressed the mica plates between the clay shields 

 of the leading-in pads, so that on the one side only the ventral 

 surface of the skin, and on the other side only its dorsal surface 



1 Monatsberichte der Akademie, 1851, p. 380. TJntersuchungen, vol. ii. part ii. 

 p. 9 f. 



2 Gesammelte Abhandlungen, etc., vol. ii. p. 261. 



3 TJntersuchungen, loc. cit. pp. 16, 17. 



* Archiv fur Anatomie, Physiologie, etc., 1865, p. 309- 



