. Behavior of the lower organisms. Animal behavior; Invertebrates. 86 BEHAVIOR OF THE LOWER ORGANISMS the backward stroke of the oral cilia is more powerful than that of the opposing aboral cilia. For the same reason the animal turns toward the aboral side even when in the position shown in Fig. 63, a, where it would be more direct to turn toward the oral side. Between this posi- tion (a) and the transverse position with oral side to the cathode (e), there is a position in which the tendencies to turn in opposite directions are exactly balanced (/). The animal tries, as it were, to turn in opp
. Behavior of the lower organisms. Animal behavior; Invertebrates. 86 BEHAVIOR OF THE LOWER ORGANISMS the backward stroke of the oral cilia is more powerful than that of the opposing aboral cilia. For the same reason the animal turns toward the aboral side even when in the position shown in Fig. 63, a, where it would be more direct to turn toward the oral side. Between this posi- tion (a) and the transverse position with oral side to the cathode (e), there is a position in which the tendencies to turn in opposite directions are exactly balanced (/). The animal tries, as it were, to turn in opposite directions at the same time, so that it remains in position, though the. (/- Fig. 63. — Effects of the electric current on the cilia of Paramecia, and direction of turning in different positions. The oral side is marked by an oblique line. The large arrows show the direction toward which the animal turns. The small internal arrows indicate the direction in which the cilia of the corresponding quarter of the body tend to turn the animal. In all positions save c and e the cilia of different regions oppose each other. From a to d the turning is toward the aboral side; from d to /, toward the oral side. At / the impulse to turn is equal in both directions, and there is no result till by revolution on the long axis the animal comes into a position with aboral side to the cathode. cilia are beating violently, causing complicated currents in the water. This independent and opposing activity of the cilia of different parts of the body is characteristic of the effects of the electric current, and is not found in the reactions to other stimuli. In the position shown in Fig. 63, /, the revolution on the long axis, which is a part of the normal motion of the animal, soon interchanges the position of oral and aboral sides, whereupon the infusorian of course turns at once towards the aboral side, till its anterior end is directed toward the cathode. Thus in a considerable preponderan
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