Page:Life Movements in Plants.djvu/231

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MECHANICAL STIMULUS ON GROWTH
201


minutes, the rate became 0°14 ,u per second; after an hour 'the recovery was complete, the Me being new 0'18 ,1. per second, the normal 'ate before stimulation (Fig. 74a). We shall presently see that not oniy is the growth rate greatly depressed under intense stimulation, but the period of recovery also becomes very much pro- tracted.

I have often been puzzled by the fact, that specimens apparently vigorous exhibited little or no growth, after attachment to the recorder. After waiting in vain for an hour, I had to discard them for others with equally un- satisfactory results. One of these specimens happened to he. left attached to the recorder overnight, andI was surprised to find that the specimen, which had shown no growth the

l<‘m.74.——(a) N, normal rate of growth; l“, retarded rate iunnediately after friction; A, partial recovery after [:3 minutes.

(b) N, normal; W, immediately after wound; (I, an hour after. (Successive dots at intervals of 5".)

previous evening, was now exhibiting vigorous growth after being left to itself for 12 hours. I then realised that the