Page:Life Movements in Plants.djvu/227

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ELECTRIC STIMULUS ON GROWTH
197

stimulus in retarding the rate of growth. The normal rate of growth of the bud of Crinum was 0.35 μ per second. On the application of electric shock of unit intensity for 5 seconds, the rate became reduced to 0.22 μ per second. When the stimulus was increased to 2 units, the retarded rate of growth was 0.07 μ per second. When the intensity was raised to 4 units, there was a complete arrest of growth. In figure 72 is given records of a different experiment which show the effects of increasing intensity of stimulus in retardation of growth.

Effect of continuous stimulation: Experiment 75.—The effect of continuous stimulation of increasing intensity will be seen in the record (Fig. 73), taken on a
Fig. 73.—Effect of continuous electric stimulation of increasing intensity. The last record exhibits
the actual shortening of the growing organ under strong stimulus. moving plate. On application of continuous stimulus of increasing intensity an increased flexture was produced in the curve, which denoted greater retardation in the rate

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