[14] That it can scarcely be _electrical induction_ would seem to be shown by the fact that such effects can only be produced on nerves by strong currents, and also by the fact that the saline tissues of the swimming-bell must short-circuit any feeble electrical currents as soon as they are generated. I have now to detail another fact of a very puzzling nature, but one which is certainly of importance. When the spiral section is performed on Aurelia aurita, and when, as a consequence, the contraction-waves which traverse the elongating strip become at some point suddenly blocked, if the section be stopped at this point it not unfrequently happens that after a time the blocking suddenly ceases, the contraction-waves again passing from the strip into the umbrella as freely as they did before the section reached the point at which the blocking occurred. The time required for this restoration of physiological continuity is very variable, the limits being from a few seconds to an hour or more; usually, however, it is from two to four minutes. This process of re-establishing the physiological connections, although rapid, is not so instantaneous as is that of their destruction by section. In general it requires the passage of several contraction-waves before the barrier to the passage of succeeding waves is completely thrown down. The first wave which effects a passage appears to have nearly all its force expended in overcoming the barrier, the residue being only sufficient to cause a very feeble, and sometimes almost imperceptible, contraction of the umbrella. The next wave, however, passes across the barrier with more facility, so that the resulting contraction of the umbrella is more decided. The third wave, again, causes a still more pronounced contraction of the umbrella; and so on with all succeeding waves, until every trace of the previous blocking has disappeared. When this is the case, it generally happens that the strip will again admit of being elongated for a short distance before a blocking of the contraction-waves again supervenes. Sometimes it will be found that this second blockage will also be overcome, and that the strip will then admit of being still further elongated without the passage of the waves being obstructed; and so on occasionally for three or four stages.