xi ELECTRICAL FISHES 441 



density of the lines of current. It occasionally showed disturb- 

 ance by discharging its own batteries." A dying malapterurus 

 was placed in a small parallelepipedic glass trough, which it 

 nearly filled, and was excited by du Bois-Eeymond (4 d, ii. 640) 

 with the sliding inductorium, the coils being pushed up, and two 

 Groves in the primary circuit. Its breathing was not disturbed, 

 nor did any discharge follow. It was equally insensible to the 

 constant current from a battery consisting of thirty Groves, which 

 is noteworthy inasmuch as the relative immunity might have been 

 conjecturally referred to the time-distribution of the current (as 

 in smooth muscle). Schonlein. further communicated to the 

 author that he was unable in Cephalopoda, Crayfish, and different 

 fishes, with an induction-apparatus double the usual size, having 

 four Bunsen cells in the primary circuit, to excite any sign of 

 action when the wire from one pole (insulated right down to the 

 end) was brought as close as 1 cm. to the animal, the other 

 pole being connected with a small plate on the floor of the 

 holder. 



Gymnotus was found by Sachs to be equally immune to its 

 own shocks. He relates that "10 gynmoti were quietly extended 

 in the middle of the canoe, nearly all close together. I dipped 

 my finger in the water at a distance of three feet, and tickled the 

 back of the largest animal with a stick. Several capable persons 

 were told off to watch the animals, one to each. In spite of the 

 distance, I received an appreciable shock. Not one of the 

 animals gave the faintest sign of movement" (4 d, p. 267). 



At the same time, this immunity (as follows from the previous 

 discussion) is far from absolute. Babuchin saw a small malapte- 

 rurus that had bitten the flanks of a larger animal draw back to 

 a distance, while he received a shock at the same moment through 

 his immersed fingers, and Steiner, whose observations were con- 

 firmed by Fritsch, has seen small torpedoes twitch from shock on 

 coming into contact with larger ones. Schonlein (I.e.) states that 

 if pregnant female torpedoes from which the embryos have been 

 removed are laid, still living, upon each other, no single animal 

 will move. " They all lie in relaxed condition, or all become 

 suddenly rigid, like a frog from which the spinal medulla has 

 been extirpated. When this last occurs, a shower of electrical 

 shocks passing through the entire heap of animals is plainly felt 

 011 the hand. They contract collectively without exception." The 



