M. du Bois-Reymond on the Electrical Silure. 47 



point of view this is perhaps the best known of all electromotive 

 fish. By the introduction of the idea of the electrical plate, M. 

 Bilharz has in all probability secured the credit of having first 

 attained to a clear view of the essential structure of an electrical 

 organ. In a physiological point of view, on the other hand, 

 nothing more has hitherto been known of the Malapterurus than 

 what was known to Adauson no less than 106 years ago, namely 

 that it gives an electrical shock*. The procuring of living speci- 

 mens in Cairo appears to be attended with almost insurmountable 

 difficulties, which have been feelingly described by M. Markusen 

 in a communication to the Academy of St. Petersburgf. M. Dia- 

 manti of Cairo, a pupil of M. Matteucci, is the only person who, 

 some years ago, was permitted for a time to investigate living 

 electrical Silures, and this by the special favour of the Viceroy of 

 Egypt J. His results, however, have not been published, and 

 were even unknown to M. Bilharz, so that the latter in his memoir 

 has endeavoured to come to a conclusion as to the distribution 

 of the tensions occurring in the organ of the Malapterurus from 

 anatomical grounds. 



Thus Pacini's prolungamenti spiniformi on the hinder negative 

 surface of the electrical plates of the organ of Gijmnotus §, are re- 

 garded by M. Bilharz with great probability as nerve-tubes, which 

 immerse themselves in the plates. In the Torpedo, the nerves 

 would also pass to the lower negative surface of that structure 

 which is indicated by M. Bilharz as the electrical plate. Now as in 

 the organ of the Malapterurus the nerve-tubes pass to the hinder 

 surface of the electrical plates, Bilharz concludes that in this fish, 

 as in the Grjmnotus, the head-end is positive, and the tail-end 

 negative, so that the current in the organ will be directed from 

 the tail to the head. 



It will be easily seen what great interest now attached to the 

 exact examination of the shock of the Malapterurus, in conse- 

 quence of this opinion of M. Bilharz. The experiments were 

 made this morning in the presence of MM. Goodsir, J. Miiller, 

 G. "Wagener, and Paul du Bois-Reymond. The fish was placed 

 in a shallow, cylindrical glass jar of 15 centims. (about 6 inches) 

 in diameter, which was filled with water to a depth of about 45 

 millims. (nearly 2 inches). For conducting the current I made 

 use of two metallic saddles placed upon the fish, — the same pro- 



* Reise nach Senegall, ubersdzt von Martini. Brandenburg, 1773, 

 p. 201. 



t Bull. rhys. Math, de I'Acad. de St. P^tersbourg, vol. xii. p. 20;i, 1854. 



X Markusen, op. cit. supra, p. 208 ; and Bilharz, op. cit. supra, Preface, 

 p. vi. 



^- Sulla SlruUura intima delV Oryano elcttrico del Gimnoto e di altri 

 Pesci elettrici, &c. Firenze, 1852, pp. IG, 21. 



