was automatically applied to the plant every hour of the day and night, the responsive moment being recorded at the same time. The amplitude of responsive fall of leaf under uniform stimulus gave a measure of excitability of
Fig. 5. Curve of variation of moto-excitability of Mimosa pudica. The upper curve gives variation of temperature and the lower, the corresponding variation of excitability.
the leaf at any particular moment. In the lower curve of Fig. 5 is given the record of diurnal variation of excitability of Mimosa. Comparison of this figure with Figs. 3 and 4, will show the remarkable resemblance between the curves of diurnal movement of the Palm tree, and of diurnal variation of moto-excitability of Mimosa. The excitability of Mimosa reached its maximum at about 3
