PART I.

RESPONSE OF PLANT ORGANS.

I.—THE PROBLEM OF MOVEMENT IN PLANTS.

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Complexity of the problem—Effects of different forms of stimuli—​Diverse responses under identical stimulus—​Modi­fi­ca­tion of response determined by intensity and point of application of stimulus, and tonic condition of organ—​Response of pulvinated and growing organs—​Necessity for shortening the period of experiment[1]

II.—THE “PRAYING” PALM TREE.

Description of phenomenon—The Recording apparatus—​Record of diurnal movement of the tree—​Universality of tree movement—​Cause of periodic movement—​Periodic movement of trees, and diurnal variation of moto-ex­cit­abil­ity in Mimosa pudica—​Relative effects of light and temperature—​Physiological character of the movement—Transpiration and diurnal movement—​Diurnal movement in inverted position—​Effect of variation of temperature on geotropic curvature—​Reversal of natural rhythm by artificial variation of temperature[5]

III.—ACTION OF STIMULUS ON VEGETABLE TISSUES.

Different types of Response Recorders—Response of a radial organ—​​Response of an anisotropic organ—Response of pulvinus of Mimosa pudica—​Tabular statement of apex time and period of recovery in different plants—​Response of pulvinus of Mimosa to variation of turgor—​Different modes of stimulation[31]

IV.—THE DIURNAL VARIATION OF EXCITABILITY IN MIMOSA.