. Electro-physiology. Electrophysiology. 130 ELECTRO-PHYSIOLOGY < HAP. current. The ordiuates above the abscissa correspond with descending currents in the nerve, those below the abscissa with ascending currents. The curve (abcdc) corresponds to an entire revolution of the bridge. It is obviously easy to determine by this method the amplitude, duration, and abruptness of the oscillation within wide limits; it is also possible to lead a current into the nerve which shall correspond only with the tract (abc). The action of a single linear oscillation of current was investigated by Fuhr (15),
. Electro-physiology. Electrophysiology. 130 ELECTRO-PHYSIOLOGY < HAP. current. The ordiuates above the abscissa correspond with descending currents in the nerve, those below the abscissa with ascending currents. The curve (abcdc) corresponds to an entire revolution of the bridge. It is obviously easy to determine by this method the amplitude, duration, and abruptness of the oscillation within wide limits; it is also possible to lead a current into the nerve which shall correspond only with the tract (abc). The action of a single linear oscillation of current was investigated by Fuhr (15), using a similar apparatus to that of v. Fleischl. No special differences from the ordinary method (in which current intensity rises, as it were, with infinite steepness) could be detected in the indirectly excited muscle-twitch. Von Fleischl always saw the twitches first at a certain rate of rotation of the rheonome, at a given pitch of current oscillation. They do not last throughout the entire period of increase of intensity, but commence at a certain pitch, and soon terminate, while the curve of oscillation increases still further, and finally sinks abruptly. The sharp turning-points (kinks) of the curve are not excitatory. The re- action of the muscle during the entire period of current oscillation is thus comprised in a single contraction. Von Kries subsequently constructed a " spring rheonome " on an entirely different principle, by which he obtained linear variations of current of different steep- nesses, while the resulting intensity re- mained constant, producing oscillations of the form / . If ab (Fig. 183) is a solid or fluid conductor traversed by a constant current, there will at any two points be a difference of potential proportional to the distance between them. If c and d are then joined by a conductor, the resistance of which as compared with the resistance of cd is very high (nerve, ], it will be traversed by a current of which the intensit
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