the functional continuity of these fibres, and so to block the passage of the contraction wave. Yet this is not the case; for even in a specimen of Aurelia so severely cut as the one here represented, the contraction waves, starting from the ganglion, continued to zigzag round and round the entire series of sections. [Illustration: Fig. 10.] The second mode of section to which I have alluded is as follows (Fig. 10). The central circle (_x_) stands for an open space cut out of the umbrella; the outer circle indicates the margin of the animal, with all lithocysts save one (_l_) removed; and the median circular line represents a cut. It will be seen that the effect of this cut is almost completely to sever the mass of tissue at _z_ from the rest of the umbrella, the only connection between them being the narrow neck of tissue at _z_. Yet, in the case to which I refer, the contraction waves emanating from _l_ passed in the directions represented by the arrows without undergoing any appreciable loss of vigour. Upon completing the circular cut at _z_, the ring of tissue (_y z_) became totally paralyzed, while the outer circle, of course, continued its contractions as before. Now, the neck of tissue at _z_ measured only one-eighth of an inch across, while the ring of tissue (_y z_), when cut through and straightened out upon the table, measured one inch across and sixteen inches in length; that is to say, sixteen square inches of tissue derived its impulse to vigorous contractions through a channel one-eighth of an inch wide, notwithstanding that the latter was situated at the furthest point of the circle from the discharging lithocyst which the form of the section rendered possible. [Illustration: Fig. 11.]