Page:Life Movements in Plants.djvu/69

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.
ACTION OF STIMULUS ON VEGETABLE TISSUES
39

Effect of Increased Turgor: Experiment 12.—A young Mimosa plant was carefully transplanted and the root embedded in soil placed in a linen bag. This was held securely by a clamp, and one of the leaves of the plant attached to the recorder. Withholding of water for a day caused a general loss of turgor of the plant. A vessel full of water was now raised from below so that the linen bag containing the roots was now in water. The effect of increased turgor by suction of water by the roots became apparent by the upward movement of the leaf. The distance between the immersed portion of the plant and the leaf was 2 cm. and the up-movement of the leaf was indicated within 10 seconds of application of water (Fig. 13). The velocity with which the effect of

Fig. 13. Response of Mimosa pulvinus to variation of turgor. Increased turgor by application of water at point marked with vertical arrow induced erectile movement. Diminution of turgor by application of KNO3 solution at the point marked with the horizontal arrow, brought about the fall of the leaf within 80 seconds. Successive dots at intervals of 5 seconds. (The down curve represents up-movement and vice versâ.)