. Electro-physiology. Electrophysiology. 408 ELECTRO-PHYSIOLOGY CHAP. position of the heart obviates this striking asymmetry in the distribution of differences of potential, which is clue to the activity of the cardiac muscle. These experiments also yield di- or even triphasic effects (Fig. 135), and according to Waller's earlier observations, the apex of the heart is invariably negative at first, corresponding with a basal direction of the wave of excitation. Owing to the extraordinary sensitivity of the capillary electrometer, and its very rapid reaction, it gives us a direct reading of the
. Electro-physiology. Electrophysiology. 408 ELECTRO-PHYSIOLOGY CHAP. position of the heart obviates this striking asymmetry in the distribution of differences of potential, which is clue to the activity of the cardiac muscle. These experiments also yield di- or even triphasic effects (Fig. 135), and according to Waller's earlier observations, the apex of the heart is invariably negative at first, corresponding with a basal direction of the wave of excitation. Owing to the extraordinary sensitivity of the capillary electrometer, and its very rapid reaction, it gives us a direct reading of the action current of striated skeletal muscle, when O tetanised. If the capillary electrometer is connected with the secondary coil of an induction apparatus, each interruption or closure of the primary circuit produces a visible movement of the meniscus in the capillary (with a proper adjustment of the coil).. Fio. 130.—Simultaneous record of cardiogram (/<, !i) and electro-cardiogram (e, e). (A. D. Waller.) With Neef's vibrating hammer, the single oscillations fuse into a gray margin, which with reduced strength of current seems to blot out the sharp image of the mercury meniscus, and with increased current rises above it in measurable proportions. On applying a battery current with correspondingly rapid interrup- tions, and uniform direction, the meniscus exhibits a total shifting in the direction of the current. This, like the oscilla- tions, is smaller in proportion as the number of interruptions is greater, and vice versa. In order to detect the gray margin at high frequency, along with the total shifting, greater strength of current is required than at a lower frequency of interruption (Martins, 42). This is important in judging the observations made with the instrument, since a physiological process accom- panied by electromotive action can record itself on the capillary. Please note that these images are extracted from scanned page images that may have been digitally
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