A text-book of physiology . of cliina-clay,moistened with normal sodium chloride solution, it is important that the zinc shouldbe thoroughly amalgamated. This form of electrodes gives rise to less polarisationthan do simple platinum or copper electrodes. The clay affords a connection be-tween the zinc and the tissue which neither acts on tlie tissue nor is acted on by thetissue. Contact of any tissue with copper or jdntinum is in itself sufficient todevelope a current. 110 MUSCLE CURRENTS. [Book The greatest deflection is observed when one electrode is placedat the mid-point or equator of the
A text-book of physiology . of cliina-clay,moistened with normal sodium chloride solution, it is important that the zinc shouldbe thoroughly amalgamated. This form of electrodes gives rise to less polarisationthan do simple platinum or copper electrodes. The clay affords a connection be-tween the zinc and the tissue which neither acts on tlie tissue nor is acted on by thetissue. Contact of any tissue with copper or jdntinum is in itself sufficient todevelope a current. 110 MUSCLE CURRENTS. [Book The greatest deflection is observed when one electrode is placedat the mid-point or equator of the muscle, and the other at eithercut end; and the deflection is of such a kind as to shew that posi-tive currents are continually passing from the equator through thegalvanometer to the cut end : that is to say, the cut end is negativerelatively to the equator. The currents outside the muscle may beconsidered as completed by currents in the muscle from the cut endto the equator. In the diagram Fig. 20, the arrows indicate the. Fig. 20. Diagram illustrating the Electric Currents of Nerve and Muscle. Being purely diagrammatic, it may serve for a piece either of nerve or of muscle,except that the currents at the transverse section cannot be shewn in a nerve. Thearrows shew the direction of the current through the galvanometer. ab the equator. The strongest currents are those shewn by the dark lines, asfrom a, at equator, to x or to y at the cut ends. The current from a to c is weakerthan from a to y, though both, as shewn by the arrows, have the same direction. Acurrent is shewn from e, which is near the equator, tof, which is farther from theequator. The current (in muscle) from a point in the circumference to a pointnearer the centre of the transverse section is shewn at gh. From a to 6 or fromX to y there is no current, as indicated by the dotted lines. direction of the currents. If the one electrode be placed at theequator ab, the effect is the same at whichever of the two cut e
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