. Electro-physiology. Electrophysiology. 266 ELECTRO-PHYSIOLOGY CHAP. of eliciting any considerable negative variation of the nerve current by other than electrical stimulation. V. Uexkiill (29) has recently obtained positive results from his mechanical tetano- motor, and has, moreover, proved the justice of Bering's pre- sumption, that the whole effect will fail, or die out, even under electrical stimulation, if the long and transverse sections of the plexus are brought into circuit by dipping them into physiological saline before, or during, the appearance of the current of action. V. ELECTR
. Electro-physiology. Electrophysiology. 266 ELECTRO-PHYSIOLOGY CHAP. of eliciting any considerable negative variation of the nerve current by other than electrical stimulation. V. Uexkiill (29) has recently obtained positive results from his mechanical tetano- motor, and has, moreover, proved the justice of Bering's pre- sumption, that the whole effect will fail, or die out, even under electrical stimulation, if the long and transverse sections of the plexus are brought into circuit by dipping them into physiological saline before, or during, the appearance of the current of action. V. ELECTROMOTIVE CHANGES (ELECTROTONUS) 1. In Medullated Nerve It has already been stated that polar alterations of excita- bility appear under the action -of a battery current, flowing. FIG. 203. steadily at uniform density through any portion of a medullated nerve. These changes are not (as in muscle) confined to the points of contact with the electrodes, the visible entrance and exit of the current, but extend beyond them, not merely into the intrapolar tract, but to a greater or less extent over the extra- polar region also. As early as 1843 du Bois-Eeymond showed that there were corresponding changes of galvanic reaction which, like those of excitability, must be diagnosed as one of the manifesta- tions of electrotonus, representing in some degree two different sides of one process. Let nnf (Fig. 203) be a nerve, A and K the two electrodes through which a battery current is led in the direction A—K; A is therefore the anode, K the kathode, of the current that produces electrotonus. On making this current, all. 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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