Page:Researches on Irritability of Plants.djvu/63

40 interval the plate has moved a certain distance. There is a second key used for short-circuiting by which the clock interrupter can be put out of action. When this is done, we obtain the usual series of dots at intervals of ·1 second. It will be understood that if the whole response-record were to be made by the vibrator, as actuated periodically at intervals of 10 seconds, we should have a very long gap in the

record of the contraction-portion, since the apex is reached in 2 seconds. To obtain then a more or less continuous inscription of the entire curve, the vibrator should at first be allowed to make its normal dots ·1 second apart. This is done by taking care to commence the experiment with the clock-interrupter short-circuited. As soon as the apex point is reached the short-circuit is removed, and the succeeding record, during the recovery of the leaf, consists of dots