The reactions of Planarians to light . junction of the sides and floor of theaquarium, as well as by its manner of finally coming to rest. A typical Phagocata (Fig. n), on the other hand, exhibited The Reactions of Planarians to Light 103 almost no goniotaxis, although the worm repeatedly crossedthe line of the angle. The response to the directive influenceof the light, too, was in this case even less than that of the Fig. 13 Planaria maculata. Considerable activity was shown over this course and a decidedinability to approach the source of the light beyond about the middle of the aquarium. De
The reactions of Planarians to light . junction of the sides and floor of theaquarium, as well as by its manner of finally coming to rest. A typical Phagocata (Fig. n), on the other hand, exhibited The Reactions of Planarians to Light 103 almost no goniotaxis, although the worm repeatedly crossedthe line of the angle. The response to the directive influenceof the light, too, was in this case even less than that of the Fig. 13 Planaria maculata. Considerable activity was shown over this course and a decidedinability to approach the source of the light beyond about the middle of the aquarium. Dendroccelum just described, as is evident from the general wan-dering character of the course. Although the Phagocata in ques-tion frequented both sides of the aquarium—that which was toward 104 Herbert Eugene Walter the light, as well as the opposite side—its wanderings were in themain on the side away from the light. An hours activity is chron-icled in the record, at the close of which the worm was apparentlyas energetic as Fig. 14 Planaria gonocephala. The path is of the same generic type as with Planaria maculata(Fig. 13), and is easily distinguishable from those of Dendrocoelum, Phagocata and Bdelloura. Fig. 12 gives a characteristic record of the way in which Bdel-loura behaves. The first movement of this specimen was more The Reactions of Planarians to Light 105 toward than away from the source of the light, but very soon wig-wagging motions set in, and after every exercise of these move-ments, which were apparently in the nature of explorations, achange in the direction of the course was effected. As might beexpected, such abrupt changes in direction were more difficult ofexecution when the worm was on the surface-film. Characteristic movements of individuals of the genus Planariaare shown in Figs. 13 and 14. From these two typical records itwould be difficult to select any diagnostic points which would dis-tinguish the behavior of P. gonocephala from that of
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