. Electro-physiology. Electrophysiology. 402 ELECTRO-PHYSIOLOGY CHAP. corresponding displacement of the mercury meniscus. The quicksilver in the capillary responds even to excessively rapid variations of the current; but the instrument seems more especially appropriate to experiments on the cardiac action current. Marey (37) was the first to use this instrument in determin- ing the electrical phenomena concomitant with the cardiac systole. He found that on leading off from the ventricle of the frog or any other animal, the electrometer gave a single oscillation at each systole. If the entire h
. Electro-physiology. Electrophysiology. 402 ELECTRO-PHYSIOLOGY CHAP. corresponding displacement of the mercury meniscus. The quicksilver in the capillary responds even to excessively rapid variations of the current; but the instrument seems more especially appropriate to experiments on the cardiac action current. Marey (37) was the first to use this instrument in determin- ing the electrical phenomena concomitant with the cardiac systole. He found that on leading off from the ventricle of the frog or any other animal, the electrometer gave a single oscillation at each systole. If the entire heart is connected with it, two oscillations can be observed in the column of mercury. The one is referred by Marey to the auricular, the other to the ventri-. Fio. 129.—Photographic record of cardiac action current, a, In the Frog's heart; I, in the heart of Tnrtoise. Time-marking in seconds. (Marey.) cular systole. Marey also succeeded in fixing these movements by photographing the image of the mercury meniscus upon a very sensitive plate moving at uniform speed. He concluded from these experiments that there is at each systole only a single variation of current (Fig. 129, a and b). Burdon- Sanderson and Page employed this method as a means of con- trolling and completing their rheotome experiments. There appears to be a fundamental coincidence between the " theoretical " curve (constructed from rheotome experiments) of the variations in the frog's heart excited at one point of the ventricle, and that projected on to sensitive paper by the mercury column of the capillary electrometer. This appears directly from comparison of the two Figs. 172, l>, and loO, a. It may be seen on the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Biedermann, W. (Wilhelm), 1852-1929; Welby, Frances A. (Frances
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