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Proc. American. Acad. of Sci. Vol. 3. p. 168

Wyman on causes of movements of Plants — contractility of cells not endosmose

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[Wyman, p. 168: "Dr. Wyman had demonstrated the impossibility of this, by dissecting away the outer layers of cells without impairing at all the contractility of the capsule. He had himself come to the conclusion, that the motion is due to the spontaneous contraction of the cells on the contracting side, in the way that motion is produced in the hydroid polyps. In the contracted capsule the cells on the concave side are found to be shortened, while those on the opposite side are elongated. In the Balsam capsule the contraction is so sudden that the shortening of the cells cannot be watched, but in the Echinocystis the motion is so gradual that the change can be observed under the microscope. When gradually subjected to the action of anaesthetic agents, the capsules lose their contractility; but when suddenly placed under their influence, an immediate contraction is the usual result."]