376 OBSERVATIONS AND EXPERIMENTS 



them 1 , they swam about briskly in the little whirlpool, and as the 

 ' frog-alarum ' showed (see below, p. 384), discharged their 

 batteries repeatedly, whether to ward off fancied danger, or as an 

 expression of content, it would be difficult to say. One of the fish 

 had evidently taken a dislike to the electrodes of the frog-alarum, 

 and often attacked it with bites, which it accompanied with several 

 discharges following rapidly on each other. The sight of red 

 colours, e. g. of a stick of sealing-wax, did not appear to excite the 

 Malapterurus in the same way as it does frogs and some other 

 animals. 



Generally the Malapterurus answer every touch, even by a non- 

 conductor, with one or more discharges. Sometimes, however, they 

 escape from the hand by a violent movement, without giving a 

 shock. This shows that in the former case the discharges are 

 voluntary and not merely reflex. The frog-alarum also showed (see 

 below, p. 384) that the fish discharged many times without any 

 assignable cause. 



Other fish, which are put into the water with the Malapterurus, 

 are immediately attacked by them with electrical broadsides. One 

 sees the fish immediately lose their balance and drift apparently 

 lifeless with the side towards the light. If they are withdrawn at 

 once, such fish come to themselves again. Given over to their fate, 

 they die. The three first Malapterurus which reached Edinburgh, 

 killed all the gold-fish in the tank of a hot-house. 



One afternoon (in September, 1857) I placed in each of the tubs 

 just mentioned, with the Malapterurus already in it, a tench (tinea 

 chrysitis) about 15 c.m. long, and a loach (colitis fossilis) of the same 

 length. A violent tumult at once arose in the three tubs. Here 

 and there a tench leapt into the air, whilst the loaches, twisting 

 themselves in an eel-like fashion, coursed round the circumference 

 of the surface of water as if driven by deadly fear, and at last, one 

 after the other, threw themselves over the edge of the tub, 3-5 cm. 

 high, between the tub and the wire netting covering it. When 

 they were put in again, they escaped repeatedly, until I made the 

 edge twice as high, by letting off the water. Naturally, each 

 electrical fish of prey had equally distressed both tench and loach, 

 and the water had become turbid in each case, by the stirring 

 np of the earth with which at that time I still kept the bottom of 

 the tubs covered (see above p. 373). I should have remained in the 



1 They were of the same kind as those described in the following paragraphs as 

 experimental tubs. 



