. Electro-physiology. Electrophysiology. 132 ELECTRO-PHYSIOLOGY CHAP. by less steepness of pitch and more extended time-distribution. We may affirm without hesitation that nerve and muscle are thrown into a much more protracted state of excitation by linear variations of current of a finite pitch than by momentary stimuli. The same may be true of physiological innervation. The strikingly low rate of oscillations of the muscle-current, as noted by Loven, both in strychnin-tetanus and in voluntary innervation, on the capillary electrometer, makes it probable that a complete tetanus may none the
. Electro-physiology. Electrophysiology. 132 ELECTRO-PHYSIOLOGY CHAP. by less steepness of pitch and more extended time-distribution. We may affirm without hesitation that nerve and muscle are thrown into a much more protracted state of excitation by linear variations of current of a finite pitch than by momentary stimuli. The same may be true of physiological innervation. The strikingly low rate of oscillations of the muscle-current, as noted by Loven, both in strychnin-tetanus and in voluntary innervation, on the capillary electrometer, makes it probable that a complete tetanus may none the less occur in the frog's muscle, while induction shocks must act at considerably greater frequency to produce the same effect. II. INFLUENCE OF DIRECTION UPON THE EXCITING EFFICIENCY OF CURRENTS In addition to pitch, density, and duration, as well as kind of increase, of the exciting current, the effect of electrical excita-. FIG. 184.—Schema for the transverse excitation of nerve. (Hermann.) tion of the nerve depends, as in muscle, upon direction of current, with reference both to arrangement of fibres and to peripheral organ at the working end of the nerve. As regards the former, it was known to Galvani that transverse passage of current through a motor nerve at—as nearly as possible—right angles to the axis of the fibres produced no effect. Galvani bridged the nerve across a moist and not very thick thread (Fig. 184 a\ through which he led a constant current. In consequence of the narrow path of the current through the nerve, there are comparatively few opportunities for the formation of longitudinal components, though these are by no means entirely excluded. On the other hand, it is doubtful whether any considerable fraction of the current traverses the nerve, unless very strong currents are made. 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
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