XII. 



1. Introductory. 



UNTIL recently it had not been possible, even under favourable 

 conditions, to keep Torpedos alive in captivity more than a few days. 

 On this circumstance was founded the opinion expressed by Faraday 

 five-and-forty years ago, that in certain respects the Gymnotus was 

 better adapted than the Torpedo for researches on electrical fishes 1 ; 

 in writing on this subject later I placed the Malapterurus above 

 the Gymnotus as an object of research, observing that ' the Torpedo 

 being a sea fish could not be taken into account V The state of 

 matters has since then entirely altered. 



Not only is the art of keeping marine animals in the Aquaria which 

 have come into existence during the last twenty years so much ad- 

 vanced, that there is now no difficulty in preserving Torpedos in a 

 living state as long as is necessary ; but also the methods of railway 

 transport are now so perfect that it is possible to convey the in- 

 habitants of the ocean to great distances from the coast without risk. 

 At the very time I wrote the words above quoted, Ranvier had at his 

 disposal living Torpedos from Concarneau on the Atlantic Ocean 3 . 

 It is, however, remarkable that in the exhibition in the Champs 

 Elysees, as well as those in Munich and Vienna, these ' oldest of all 

 electrical machines,' as they were called by George Wilson 4 , were 

 wanting ; their only representatives being the submarine instru- 

 ments of warfare which have been called after them. 



Torpedos were first received at the Berlin Aquarium in the 

 summer of 1881 from Trieste. The director, Dr. Otto Hermes, 

 who makes the resources of the institution available for scientific 

 purposes with the utmost liberality and courtesy, at that time per- 

 mitted me to make some experiments. These were, however, 

 limited to such general observations as could be made without inter- 

 fering with the purpose for which the animals were kept. I have 

 repeatedly on former occasions explained why the possession of 



1 Notice of the character and direction of the electric force of the Gymnotus (1838). 



2 E. du Bois-Reymond, Gesammelte Abhandlungen, vol. ii. p. 611. 



3 Le9ons sur 1'histologie du Systeme Nerveux, Paris, 1878, vol. ii. p. 88. 



4 The Edinburgh New Philosophical Journal, Oct. 1857, P- z6 7 



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