. The Journal of experimental zoology. B p- ^rClf^W 1 \ \ m t^ < < •^ m % c. D Fig. 18 Diagram representing the relation of the axis of photic stimulationto the axes of the various rhabdomes when the eye is illuminated from differentdirections. The diagrams are made from camera-lucida drawings of sections. Aand B, frontal sections of the eye; C and D, transverse sections of the eye;A-P,antero-posterior line; D-V, dorsoventral line;o, b, c, d, arrows indicating the dif-ferent beams of light; ac, accessory cells; p, pigment-cup; 1-9, rhabdomes. REACTIONS TO LIGHT IN PLANARIA MACULATA 109 T
. The Journal of experimental zoology. B p- ^rClf^W 1 \ \ m t^ < < •^ m % c. D Fig. 18 Diagram representing the relation of the axis of photic stimulationto the axes of the various rhabdomes when the eye is illuminated from differentdirections. The diagrams are made from camera-lucida drawings of sections. Aand B, frontal sections of the eye; C and D, transverse sections of the eye;A-P,antero-posterior line; D-V, dorsoventral line;o, b, c, d, arrows indicating the dif-ferent beams of light; ac, accessory cells; p, pigment-cup; 1-9, rhabdomes. REACTIONS TO LIGHT IN PLANARIA MACULATA 109 These observations strongly support the assumption that ifhght strikes a rhabdome parallel with its longitudinal axis stimu-lation results; whereas, if light does not strike a rhabdome alongthis axis stimulation does not follow. This will explain why itis not necessary for the pigment-cup to act as a localizer ofphotic stimulation. The latter is localized not by the pigment-cup, but by the position of the longitudinal axes of the variousrhabdomes. NATURE OF THE STIMULUS DURING O
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1920
