XL 



1. Introduction. 



THE unusual interest which electrical fishes * have always excited, 

 has been increased still further at the present day, by its becoming 

 known that the endowment which made these animals so long, an 

 object of inquisitive wonder does not belong to them alone, but 

 appears to be a special application of a common property, such as 

 is frequent in the animal world. Since we have known that all 

 nerves and muscles of all animals are capable of electrical actions, 

 electrical fishes have indeed lost somewhat of their wonder, but this 

 loss is abundantly compensated by the hope which now attaches to 

 their investigation, that the solution of the great problems of the 

 general physics of nerve and muscle may be promoted by it. 



Until lately we had reason to regret, that of the three electrical 



1 My researches on electrical fishes are found in the following : I. Nachricht von 

 einem nach Berlin erlangten lebenden Zitterwelse. Monatsberichte, etc., 1857, 

 pp. 424-429 ; Moleschott's Untersuchung.cn zur Naturlehre des Menschens und der 

 Thiere, 1858, vol. iv. p. 97. II. Ueber lebend nach Berlin gelangte Zitterwelse 

 aus Westafrika. (Lecture given in the Friedrichsitze of the Academy on Jan. 28, 

 1858 ; containing a popular account of what had been ascertained up to that date 

 about the Malapterurus). Monatsberichte, etc., 1858, pp. 84-111 : Moleschott's 

 Untersuchungen, etc., 1858, vol. v. p. 109. III. Bemerkungen uber Reaction des 

 elektrischen Organes und der Muskeln, Archiv fiir Anatomic, u. s. w. 1859, 

 pp. 846-848. IV. Ueber Jodkalium Elektrolyse und Polarisation durch den Schlag 

 des Zitterwelses. Monatsberichte, etc., 1861, pp. 1105-1128; Moleschott's Unter- 

 suchungen, etc., 1862, vol. viii. p. 549. V. Beschreibung einiger Vorrichtungen 

 und Versuchsweisen zu elektro-physiologischen Zwecken. Abhandlungen der 

 Akademie, 1862, Berlin, 1863, 4. Physikalische Klasse. In xviii and xix of 

 this paper, pp. 148-162, the Frog-alarum and Frog-interrupter, of which I made use 

 in the experiments on the Malapterurus, are described. VI. Ueber die raumliche 

 Ausbreitung des Schlages der Zitterfische. Monatsberichte, etc., 1864, pp. 317-354; 

 Moleschott's Untersuchungen, etc., 1865, vol. ix. p. 437. VII. Experimentalkritik 

 der Entladungshypothese uber die Wirkung von Nerv auf Muskel. Monatsberichte, 

 etc., 1874, pp. 519-560. No. V is printed in the first volume of the Collected Papers, 

 pp. 213-227. IV, VI, and VII follow here as Abh. XXIX, XXX, and XXXI. The 

 present paper, XXVIII, takes the place of the three first numbers for the reasons 

 stated in the preface to this volume. 



Bb 



