. Electro-physiology. Electrophysiology. ii CHANGE OF FORM IN MUSCLE DURING ACTIVITY 71 blooded muscle, Eichet in the muscles of crab, and Eomanes in medusa (24). If uniform induction currents are sent rhythmic- ally through the resting apex of the frog's heart, a ladder, or " staircase," of contractions with increasing amplitude is almost invariably exhibited, as shown in the accompanying series of curves (Fig. 37). Tiegel ( p. 37) observed an analogous effect in curarised FIG. 37.—Heart (Frog) artificially excited after ligature of the sinus. The first notch of each curve is pr
. Electro-physiology. Electrophysiology. ii CHANGE OF FORM IN MUSCLE DURING ACTIVITY 71 blooded muscle, Eichet in the muscles of crab, and Eomanes in medusa (24). If uniform induction currents are sent rhythmic- ally through the resting apex of the frog's heart, a ladder, or " staircase," of contractions with increasing amplitude is almost invariably exhibited, as shown in the accompanying series of curves (Fig. 37). Tiegel ( p. 37) observed an analogous effect in curarised FIG. 37.—Heart (Frog) artificially excited after ligature of the sinus. The first notch of each curve is produced by the auricular, the proper summit by the ventricular systole. Both exhibit the staircase. (Engelmann.) frog muscles (gastrocnemius) with intact circulation. If single induction shocks of uniform strength are sent into such a muscle at regular intervals, the height of contraction increases constantly, so long as maximal stimuli are employed, even in a series of several hundred contractions, so that the height of the " stair- case " ( the curve which unites the joint summits of an ascend- series of contractions) increases within certain limits with. Fin. 3S.—Excitation of a somewhat exhausted bloodless gastrocnemius of Frog, by groups of 1, 2, 3, 4, 5, uniform maximal break induction shocks. Increase in height of contraction with repeated excitation at short intervals ("staircase"). Decrease on longer duration of the pauses (tuning-fork, ,V sec.) (Engelmann.) the strength of the individual stimuli. On the application of minimal stimuli, there is, as a rule, no increment of the contrac- tion series, or at most a trace only, whereas in the maximal series it is invariably well developed (Fig. 38). If such a series is interrupted and resumed after a pause, the first of the new- contractions is smaller than the last before the interval (Tiegel, Eossbach, Buckmaster), but the muscle immediately resumes its increasing contractions. Within a certain r
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