426 ELECTRO-PHYSIOLOGY CHAP. 



to detect " any appreciable response " in a nerve-organ preparation 

 of Gymnotus with the strongest single induction shocks obtained 

 from a sliding inductorium by means of the thermo-electric 

 battery (4 e, p. 192), and he also failed to get response from 

 the make and break of the current of four Groves in either 

 direction. Sachs apparently refers this to a special property 

 of the electrical nerves, and not to the organ, ascribing to 

 the former a " more solid molecular constitution " and " more 

 stable equilibrium" than to the nerves of other animals. Du 

 Bois-Keymond, on the other hand, points with justice to the 

 part played by the electrical plates of the organ, the 

 similarity of conditions under which the electrical excitation 

 of sensory nerves will discharge reflex movements, and an 

 analogous stimulation showing the electrical organs. " Gentle 

 tetanisation of the sensory nerves produces marked reflex 

 twitches of certain groups of muscles from the cord ; strong 

 single shocks elicit no response. Strong single shocks sent 

 into the electrical nerves discharge no shock from the organ, 

 while it responds by tetanus to the gentle tetanisation of the 

 electrical nerves. The electrical plates of the organ therefore 

 react to the two forms of excitation of the electrical nerves, 

 as the ganglion-cells of the cord respond to the same kinds of 

 stimulation of the sensory nerves" (4 e, p. 272). Eckhardt 

 (11) repeatedly and successfully excited the electrical nerves of 

 Torpedo with single induction shocks, as well as with the constant 

 current. In the last instance Schonlein (I.e.) again observed a 

 peculiar response of the nerve-organ preparation of Torpedo. 

 On leading off from a bit of the organ, with a current of 1 6 Dan. 

 and 6 Bunsen passing through the nerve, he found, "according to 

 the direction of current at closure or opening of the exciting 

 circuit, or even at both, a single movement of the scale ; during 

 closure, there was in addition a permanent deflection/' the direc- 

 tion of which appeared to be independent of that of the current. 

 The possibility of current escape seemed excluded, since on cutting 

 through the nerve and laying the ends together again, as well as on 

 ligaturing it, the deflections were entirely abolished. There is 

 no adequate explanation of this effect, which Sachs apparently 

 noted on Gymnotus also (4 e, p. 189). 



After this discussion it is unnecessary to state that the much 

 more effective tetanising excitation from the nerve produces, as in 



