Further Observations on the Locomotor System of Medusae . ive shortening of the intervals betweensuccessive stimuli has the effect of progressively diminishing the number of steps in astaircase, and this by increasing the difference between the heights of the successive , if a staircase has been built up by shocks thrown in at seconds intervals, and therate of stimulation be now suddenly changed to six seconds intervals, the maximum levelof the tracing that was obtained by the more rapidly succeeding shocks may be observedslightly to sink. This greater tolerance of the medusoid than
Further Observations on the Locomotor System of Medusae . ive shortening of the intervals betweensuccessive stimuli has the effect of progressively diminishing the number of steps in astaircase, and this by increasing the difference between the heights of the successive , if a staircase has been built up by shocks thrown in at seconds intervals, and therate of stimulation be now suddenly changed to six seconds intervals, the maximum levelof the tracing that was obtained by the more rapidly succeeding shocks may be observedslightly to sink. This greater tolerance of the medusoid than of the cardiac tissuetowards rapidity in the succession of stimuli is doubtless connected with the samedifi^erences in their constitution that leads to what I have called the shorter memory ofthe one than of the other. In this connexion it may also be stated that a staircasehas more steps in it if caused by a weak than if caused by a strong current (comparefigs. 1 & 4), and that if the strength of the current be suddenly increased after the Fig. maximum level of a staircase has been attained by a feeble current, this level admits ofbeing slightly raised (see fig. 4). Lastly, the cases of the heart and of Aurelia appear not quite to coincide in oneother particular; for I find that in Aurelia the staircase action is so pronounced^ thata stimulus which at the bottom of a staircase is of less than minimal intensity, is able,at the top of a staircase, to give rise to a contraction of very nearly maximum is to say, by employing an induction stimulus of slightly less than minimal inten-sity in relation to the original irritability of the tissue, no response is given to the firsttwo or three shocks of a series; but at the third or fourth shock a slight response isgiven, and from that point onward the staircase is built up as usual. This was thecase in the experiment of which fig. 1 is a record^ no response having been given to thefirst two shocks. Now, as Dr. Bowdit
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectproceed, bookyear1877
