_Effect of Drought: Experiment 3._--In Fig. 6 is given a series of records of movement of the leaf-stalk of _Arenga_, first under normal condition, afterwards under increasing drought, brought about by withholding water. The uppermost is the thermographic record which remained practically the same for successive days. Below this are records of movement of the leaf (_a_) under normal condition, (_b_) after withholding water for three days, and (_c_) after deprivation for seven days. It will be noticed how the extent of movement is diminished under increasing physiological depression brought on by drought. On the seventh day, the responsive movement disappeared, there being now a mere fall of the leaf, which was slow and continuous. After this I supplied the plant with water and the periodic movement was in consequence nearly restored to its original vigour. _Effect of poison: Experiment 4._--In another experiment the normal diurnal record with the leaf was taken and the plant was afterwards killed by application of poisonous solution of potassium cyanide. The diurnal movement was found permanently abolished at the death of the plant. [Illustration: Fig. 6. Effect of physiological depression on diurnal movement of the petiole of _Arenga saccharifera_. The uppermost curve exhibits variation of temperature, (_a_), normal diurnal curve, (_b_), modification after 3 days’ and (_c_) after 7 days’ withholding of water.] These experiments conclusively prove that the periodic movement of the leaf-stalk induced by variation of temperature is a physiological phenomenon, and from analogy we are justified in drawing the inference that the movement of the Faridpur tree is also physiological. The question, however, was finally settled by the unfortunate death of the tree which occurred the other day, nearly a year after I commenced my investigations. While presiding at my lecture on the subject, His Excellency Lord Ronaldshay, the Governor of Bengal, announced that a telegram had just reached him from his officer at Faridpur that “the palm tree was dead, and that its movements had ceased.” Since my investigation with the Faridpur ‘Praying’ Palm, I have received information regarding other Palms, which exhibit movements equally striking. One of the trees is growing by the side of a tank, the trunk of the tree being inclined towards it. The up-lifted leaves of this tree are swung round in the afternoon and dipped into the water of the tank. The movement of the tree has been shown to be brought about by the physiological action of temperature variation; in other words the diurnal movement of the ‘Praying’ Palm is a THERMONASTIC PHENOMENON. I have found various creeping stems, branches and leaves of many trees, exhibit this particular movement of fall with a rise of temperature, and _vice versâ_. Such movements, I shall, for the sake of convenience, distinguish as belonging to the _negative type_.