. A text-book of human physiology . Opening C O or weak C C — contraction ; 0 = no contraction. 424 THE FUNCTIONS OF CROSS-STRIATED MUSCLES It will be understood that the terms weak, medium, and strong as appliedto the current in this discussion do not designate any absolute values of thecurrent, since what is medium current for one nerve-muscle preparation maybe strong for another. The terms are purely relative to any given preparation. This peculiar behavior of a nerve-muscle preparation to currents of dif-ferent strength, which finds expression in the law of contraction, dependsupon another
. A text-book of human physiology . Opening C O or weak C C — contraction ; 0 = no contraction. 424 THE FUNCTIONS OF CROSS-STRIATED MUSCLES It will be understood that the terms weak, medium, and strong as appliedto the current in this discussion do not designate any absolute values of thecurrent, since what is medium current for one nerve-muscle preparation maybe strong for another. The terms are purely relative to any given preparation. This peculiar behavior of a nerve-muscle preparation to currents of dif-ferent strength, which finds expression in the law of contraction, dependsupon another law enunciated bv Pfliiger, namelv, that a constant current has. Fig. 101.—Catclectrotoiuis. The tracing is to be read from right to left. The nerve was firststiuiulateil in the neigliborliood of the catiiode of the polarizing current with stimuli too weakto produce any effect while the polarizing current was not running. The polarizing then turned on, and, without changing the strength of the stimuli, thej became the polarizing current was again turned off, the stimuli were again subminimal. no stimulating action on the nerve between the poles, but acts only at thepoles. O71 closing the current the stimulus starts from the cathode, on openingfrom the anode. This 2>otar law of excitation may be illustrated by the following experimentalfacts. If in stimulating with the constant current the electrodes be applied tothe nerve as far apart as possible, and the latent period of the closing contrac-tions be determined both for the ascending and descending currents, we findthis period to be longer for the former than for the
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