. Electro-physiology. Electrophysiology. Ill ELECTRICAL EXCITATION OF MUSCLE 177 detected even at a slow rate of the recording surface, but is much plainer with a quick movement. According to Tigerstedt (2) the process of each make contraction must be of a tetanic character, since the corresponding curves are much more ex- tended than in twitches provoked by induction currents (Fig. 72). But it is needless to say that there is not necessarily any true " tetanus," contraction resulting from summation. From these facts alone we may conclude that besides the intensity of current, i
. Electro-physiology. Electrophysiology. Ill ELECTRICAL EXCITATION OF MUSCLE 177 detected even at a slow rate of the recording surface, but is much plainer with a quick movement. According to Tigerstedt (2) the process of each make contraction must be of a tetanic character, since the corresponding curves are much more ex- tended than in twitches provoked by induction currents (Fig. 72). But it is needless to say that there is not necessarily any true " tetanus," contraction resulting from summation. From these facts alone we may conclude that besides the intensity of current, its duration in the muscle also affects the strength of excitation (or contraction), while this appears yet more plainly from corresponding experiments on sluggish muscles,. FK.;. 72.—1-S, Contraction curves on excitation of the muscle by single induction shocks ; 9-iy, con- traction curves (make twitches) on exciting with the constant current ("tetanus " character). (Tigerstedt.) where the magnitude of effect as dependent upon the duration of the excitation appears to be in exact inverse ratio with the mobility of the particles of an irritable substance. The extra- ordinarily small and often negative effect of single induction shocks on many protozoa, and on vegetable protoplasm, is well known, while in smooth muscle such short stimuli, if they act at all, first take effect at a high intensity, although they seldom or never fail to excite the rapidly twitching striated fibres. This is remarkably well seen on every relaxed (a-tonic) pre- paration from the adductor muscles of anodonta (3). From these, as was said above, it is easy to obtain a preparation as susceptible to electrical excitation as the frog's sartorius (Fig. 73). N. 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. (Wilh
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