. Electro-physiology. Electrophysiology. 276 ELECTRO-PHYSIOLOGY CHAP. pointed out, the electrotonic alterations (unlike excitation) diminish rapidly in intensity with increasing distance from the polarised tract, and finally become imperceptible. So that, when immediately after closure of the polarising current the electro- tonus is still undeveloped, the region in which it can be demonstrated is necessarily even smaller than that in which it appears definitely. Tschirjew subsequently repeated his experiments with the same results, using the capillary electrometer (which is peculiarly sensitiv
. Electro-physiology. Electrophysiology. 276 ELECTRO-PHYSIOLOGY CHAP. pointed out, the electrotonic alterations (unlike excitation) diminish rapidly in intensity with increasing distance from the polarised tract, and finally become imperceptible. So that, when immediately after closure of the polarising current the electro- tonus is still undeveloped, the region in which it can be demonstrated is necessarily even smaller than that in which it appears definitely. Tschirjew subsequently repeated his experiments with the same results, using the capillary electrometer (which is peculiarly sensitive to rapid oscillations of current), and Bernstein's rheotome,. FIG. 210. which of course are open to the same objections. Bearing in mind the theory of this last ingenious instrument, it is evident that it affords an easy means of leading a polarising current at any given moment into the nerve, and interrupting it again directly, at the same time leading off the electrotonic currents from a distant tract of the nerve at different intervals after closure. Bernstein's own method of experiment (as referred to above) is explained by the following schema (Fig. 210). During the rotation of the rheotome the polarising current is periodically closed whenever the contacts dip into the mercury pools (qq), the galvanometer circuit as often as the contact (^j1) dips into (ql). The period of closure of the polarising current varies between - and sec.: the direction of the led-off current. 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 Alice). London : Macmillan
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