D.K. PUBLISHERS’ DISTRIBUTORS 1, ANSARI ROAD, DARYA GANJ, NEW DELHI-110002 (INDIA) PHONE: 27-8368 _Printed at_: BRITE PRINTERS NEW DELHI-110005 (INDIA) CONTENTS PART I. RESPONSE OF PLANT ORGANS. I.--THE PROBLEM OF MOVEMENT IN PLANTS. PAGE 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_. Apparatus for study of variation of excitability--Uniform periodic stimulation--The Response Recorder--Effects of external condition on excitability--Effects of light and darkness--Effect of excessive turgor--Influence of temperature--Diurnal variation of excitability--Effect of physiological inertia 43 V.--RESPONSE OF PETIOLE-PULVINUS PREPARATION OF _MIMOSA_. Effect of wound or section in modification of normal excitability--The change of excitability after immersion in water--Quantitative determination of the rate of decay of excitability in an isolated preparation--Effect of amputation of upper half of the pulvinus--Effect of removal of the lower half--Influence of weight of leaf on rapidity of responsive fall--The action of chemical agents--Effect of “fatigue” on response--The action of light and darkness on excitability 73 VI.--CONDUCTION OF EXCITATION IN PLANTS.