The persistent effect of rise of temperature is a movement downwards, that of fall of temperature is a movement upwards. These definite reactions will be seen exhibited in Figs. 8 and 9. The plant was stationary at the turning point in the morning hence the curve at first was horizontal. The temperature was gradually lowered through 5°C., from 29°C., to 24°C. in the course of five minutes and maintained at the lower temperature. There was no immediate effect, but after a latent period of 65 minutes the plant responded by a movement of erection. The natural movement at this period of the day would have been one of fall, but artificial change of temperature in the opposite direction effectively reversed the normal diurnal movement. The latent period for this reverse movement is, as stated before, 65 minutes as against 50 minutes in the normal diurnal movement. The increase in the latent period is probably due to the added physiological inertia in reversing the normal rhythm. _Effect of rise of temperature: Experiment 9._--The temperature was raised through 5°C at the second turning point, at 1 P.M. After a latent period of 50 minutes the plant began to rise steadily (Fig. 9) thus exhibiting once more the reversal of its normal diurnal movement. From the experiments described above it will be seen that the movement of the Palm, and of other organs growing at an inclination to the vertical, is brought about by the action of temperature in modifying the geotropic curvature. The ever present tendency of geotropic movement is opposed or helped by the physiological reaction induced by rise and fall of temperature respectively. The state of equilibrium is never permanent, but the dynamic balance is being constantly readjusted under changing conditions of the environment. The movement of the tree furnishes an example of the _negative_ type of THERMONASTIC MOVEMENT. Parallel phenomena are found in floral organs, where, in the well-known instance of _Crocus_, the perianth leaves open outwards during rise of temperature and close inwards during the onset of cold. Looked at from above, the opening outwards during rise of temperature is a movement downwards, and therefore belongs to the _negative type_. In such cases the changed rate of growth by variation of temperature is the most important factor in the movement. It may be asked whether all thermonastic movements must necessarily belong to the _negative_ type, where rise of temperature is attended by a movement downwards. I shall in my Paper on “Thermonastic Phenomena” show that there is also a _positive type_ where rise of temperature induces an up-movement or of closure. SUMMARY. The ‘Praying’ Palm of Faridpur, growing at an inclination of about 60° to the vertical, exhibited a diurnal movement by which its head became erected in the morning and depressed towards the afternoon, the outspread leaves pressing against the ground.