Papers From the Tortugas Laboratory of the Carnegie Institution of Washington
Papers From the Tortugas Laboratory of the Carnegie Institution of Washington
Carnegie Institution of Washington. Tortugas Laboratory
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The starfish began to move in a certain direction and was then turned around through 180°; the restdt was that the specimen then moved in the opposite direction. In other words, a starfish which reacted nega- tively to bright light by moving away from it, reacted positively to bright light by moving toward it when rotated through 180®. This behavior Bohn interprets as a change in sign of "phototropisme." It is true that Asterina changed its direction of movement with reference to the more inten...sely lighted region, but this was undoubtedly not due Digitized by Google Reaction to Light and other Points in Behavior of Starfish. 109 to any change in the stimulus produced by light. Such behavior, it seems to me, should be explained by the persistence of the ** coordinated impulse" (Jennings, 1907), The starfish had been placed in the lighted field ; some stimulus (either the light or other external or internal stimuli) so affected the creature that the tube feet began to move coordinately, resulting in locomotion with a certain ray of interradius directed for- ward; the asterina moved in a definite direction, namely, away from the light; when this impulse was firmly established and the starfish was moving away from the brightly lighted region it was turned through 180*^; the established impulse to move with a certain ray or interradius forward persisted and the starfish then moved toward the light.
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