Page:Life Movements in Plants.djvu/93

Rh from 6 to 9, after which there is a reverse movement of erection. In certain specimens, however, the erectile movement commenced as early as 6 It is obvious that in these latter cases diminution of amplitude of response cannot be due to the reduction of the range of movement of the leaf. In Fig. 25 is given a series of

records from 6 to 10 obtained with a leaf in which erectile movement had commenced early in the evening. Though the full range of responsive movement was in this case available, yet the amplitude of successive responses is seen to undergo continuous diminution.

Record in the morning: Experiment 22.—The excitability is, as we have seen, nearly abolished about 8, after which there is a gradual restoration. This gradual enhancement of excitability to a maximum in the course