. Behavior of the lower organisms. Animal behavior; Invertebrates. i56 BEHAVIOR OF THE LOWER ORGANISMS (4) If Colpidium is squarely transverse, with oral side to the cathode (Fig. 104, 1), or especially if the anterior end is a little inclined toward the anode, the organism often starts trans- versely to the current. Suddenly it jerks its body a little toward the aboral side (Fig. 104,1-2), then moves forward again. Again it jerks toward the aboral side (3), again moves forward, and repeats this behavior until the anterior end is directed toward the anode. Then it turns steadily toward the abo
. Behavior of the lower organisms. Animal behavior; Invertebrates. i56 BEHAVIOR OF THE LOWER ORGANISMS (4) If Colpidium is squarely transverse, with oral side to the cathode (Fig. 104, 1), or especially if the anterior end is a little inclined toward the anode, the organism often starts trans- versely to the current. Suddenly it jerks its body a little toward the aboral side (Fig. 104,1-2), then moves forward again. Again it jerks toward the aboral side (3), again moves forward, and repeats this behavior until the anterior end is directed toward the anode. Then it turns steadily toward the aboral side till the anterior end is directed toward the cathode (Fig. 104, 4-5). In this behavior the two tendencies mentioned oppose each other, as in case 2, but the second one prevails over the first. Various combinations of these different reaction types may occur, making the be- havior of Colpidium under the electric cur- rent very complicated. Similarly varied be-. 0 — Fig. 104. — Another method of reaction to the electric current havior is often observed in other infusoria, in Colpidium. After Pearl through the action of similar causes. (1900). as In such + infusoria as Stentor, where the peristomal cilia form a circle surrounding the anterior end, there is no reason for such a conflict of tendencies. The peristomal cilia are divided by an electric current coming from one side, so that the ani- mal turns directly away from the side on which these cilia strike backward (Fig. 105). If the anterior end is directed toward the anode at the beginning, the animal doubtless turns as usual toward the right aboral side. In other positions the usual method of turning seems to have no effect on the reactions. In Vorticella and other infusorians resembling Stentor in the distribution of the cilia, the orientation to the current would doubtless take place in the same direct manner, though this has never been determined. In Spirostomum and Opalina, the conflict of the two tendencies
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