Turgor variation under transverse transmission of stimulus-effect--Tropic responses of pulvinated and growing organs to unilateral stimulation--Direct unilateral stimulation--Indirect unilateral stimulation--Difference of effects induced by Direct and Indirect stimulation--Laws of tropic curvature 279 XXVI.--MECHANOTROPISM: TWINING OF TENDRILS. Anomalies of mechanotropism--Effects of indirect and direct electric stimulation on growth of tendril--Effect of direct and indirect mechanical stimulus--Immediate and after-effect of stimulus--Inhibitory action of stimulus--Response of less excitable side of the tendril--Relative intensities of responses of upper and under sides of tendril of _Passiflora_--Negative curvature of tendril 288 XXVII.--ON GALVANOTROPISM. Polar effects of electric current on growth--Effect of anode and cathode on growth 301 XXVIII.--ON THERMONASTIC PHENOMENA. Effect of temperature--Different thermonastic organs--Two types of response: Positive and Negative--Effect of rise of temperature and of stimulus on thermonastic organs--Law of thermonastic reaction 305 XXIX.--ON PHOTOTROPISM. Complexity of problem of phototropic reaction--Action of light--Positive phototropic curvature of pulvinated organs--Positive phototropic curvature of growing organs--Phenomenon of recovery--Immediate and after-effect of light on growth--Latent period of phototropic reaction-- Growth variation induced by flash of light from a single spark--Maximum positive curvature under continued action of light 313 XXX.--DIA-PHOTOTROPISM AND NEGATIVE PHOTOTROPISM. Differential excitability of two halves of pulvinus of _Mimosa_--Transformation of positive to negative curvature--Tropic effect under sunlight--Negative phototropism of shoot and root 328 XXXI.--RELATION BETWEEN THE QUANTITY OF LIGHT AND THE INDUCED PHOTOTROPIC CURVATURE. Effect of increasing intensity of light on pulvinated and growing organs--Effect of increasing angle--Effect of duration of exposure 338 XXXII.--THE PHOTOTROPIC CURVE AND ITS CHARACTERISTICS. Summation of stimulus--General consideration--The general characteristic curve--Characteristics of simple phototropic curve--Variation of susceptibility for excitation in different parts of the curve--Effect of sub-minimal stimulus--The complete phototropic curves of pulvinated and growing organs--Limitation of Weber's law 346 XXXIII.--TRANSMITTED EFFECT OF PHOTIC STIMULATION.