. The Journal of experimental zoology. is due to the momentary glowingof one concentric line of points after another as the impulse thatinduced the phosphorescence spreads from the center of stimu-lation outward. This spread of light from the center of stimu-lation to the rest of the colony in other sea-pens than Renilla wasapparently first recorded by delle Chiaje in 1836 (Panceri 71,p. 11). As with rachidial peristalsis, the waves of luminosity passaround incisions in the rachis, provided these incisions do notcompletely separate the parts concerned. If the rachis is cutnearly in two transve
. The Journal of experimental zoology. is due to the momentary glowingof one concentric line of points after another as the impulse thatinduced the phosphorescence spreads from the center of stimu-lation outward. This spread of light from the center of stimu-lation to the rest of the colony in other sea-pens than Renilla wasapparently first recorded by delle Chiaje in 1836 (Panceri 71,p. 11). As with rachidial peristalsis, the waves of luminosity passaround incisions in the rachis, provided these incisions do notcompletely separate the parts concerned. If the rachis is cutnearly in two transversely, the luminous waves may be started 494 G. H. PARKER by mechanical stimulation in either part and will pass thenceover the connecting bridge of tissue to the other part. If twosymmetrical transverse cuts are made leaving the two parts con-nected by a narrow axial bridge, the luminous waves will passfrom the peduncular to the apical piece or the reverse with per-fect freedom. If the region of stimulation is axial in position, the. Fig. 9 An almost divided Renilla stimulated at *S for phosphorescence. Theluminous waves in the peduncular portion of the rachis are unsymmetrical; inthe apical part, in consequence of the median position of the bridge, they aresymmetrical. Fig. 10 A Renilla partly divided by two longitudinal slits. When the stimu-lus to phosphorescence is applied in a median position (S), the luminous waveshave a symmetrical course (solid arrows); when it is applied in a lateral position(dotted S), the course is unsymmetrical (dotted arrows). Fig. 11 A Renilla whose rachis has been cut into a scroll and is somewhatunfolded. A stimulus to phosphorescence applied at S is followed by a lumi-nous wave that takes the course of the arrows. spread of the wave over the stimulated part as well as over theunstimulated one is symmetrical with reference to the axis. Ifthe region of stimulation is lateral to the axis (fig. 9), the spreadof the wave is unsymmetrical in the sti
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1920
