LIVING TORPEDOS IN BERLIN. 427 



that of the Torpedo l . The influence of the good conductivity of 

 the medium on the strength of the shock was clearly shown in 

 Dr. Hermes' experiment with a Malapterurus, which every time 

 that it was brought (for a curative purpose) into a physiological 

 salt solution, just as in my observations on the gastrocnemius of 

 the frog 2 , apparently lost its electrical properties 3 . 



The late A. von Bezold, who helped me in my experiments on 

 Malapterurus, suggested that the shocks might be strengthened by 

 the substitution in the experimental vessel of aerated distilled 

 water for river water 4 . As many fish ascend rivers from the sea 

 (e. g. the Narcine Brasiliensis brought to Humboldt in Cumana as 

 Tremblador or Gymnotus, was fished from the Manzanares 5 ), it 

 might presumably be possible without great risk to transfer a 

 Torpedo for a time into fresh water. I would gladly have 

 attempted to make observations on the strengthening of the shock 

 which might be looked for under these circumstances, but on 

 account of the sluggishness of the Torpedo it would have been 

 fruitless to make comparative series of observations on the strength 

 of the shock under varying conditions. 



7. On the distribution of the current in the Torpedo. 



The accompanying woodcut is a faithful reproduction of a figure 

 by Cavendish, who, more than a century ago, in his endeavours to 

 imitate by ordinary electricity the 

 Torpedo-shock, first conceived the 

 idea of current curves, and was so 

 much in advance of his time in 

 his understanding of this process [ \ \ 

 in the animal, that Faraday was * 

 the first after him to attain to 

 the same standpoint. Cavendish 

 sought to accomplish his purpose Fig I4> 



by means of a leather model of 



the fish soaked with sea water ; he covered the spots corresponding 

 to the polar surfaces of the organ with tinfoil, and connected them 

 by insulated wires with a Leyden battery 6 . By this means the 

 polar surfaces became isoelectrical. Cavendish passed over in 



1 Untersuchungen, p. 411. 2 Gesammelte Abhandlungen, vol. ii. p. 379. 



3 Untersuchungen, pp. 409, 411. * Gesammelte Abhandlungen, p. 613. 



5 Untersuchungen, pp. 76, 282, 411. 



6 The Electrical Kesearches of the Hon. Henry Cavendish, edited by J. Clerk 

 Maxwell, Cambridge, 1879, p. 194. 



