Effect of light applied on tip of Setaria--Response of growing region to unilateral stimulus--Effect of simultaneous stimulation of the tip and the hypocotyl-- Algebraical summation of effects of direct and indirect stimuli 362 XXXIV.--ON PHOTONASTIC CURVATURES. Phototropic response of anisotropic organs--Positive para-heliotropism--Negative para-heliotropism--Responses of pulvinated and growing organs to light 378 XXXV.--EFFECT OF TEMPERATURE ON PHOTOTROPIC CURVATURE. Effect of temperature on excitability--Effect of temperature on conduction--Phototropic response of tendrils--Seasonal variation of phototropic curvature--Antagonistic effects of light and of rise of temperature 388 XXXVI.--ON PHOTOTROPIC TORSION. Torsional response to light--Effect of different modes of lateral stimulation--Effect of differential excitability on the direction of torsion--Laws of torsional response-- Complex torsion under light--Advantages of the Method of Torsional Response--The Torsional Balance--Determination of the direction of stimulus 397 XXXVII.--RADIO-THERMOTROPISM. Effect of infra-red radiation--Positive radio-thermotropism-- Dia-radio-thermotropism--Negative radio-thermotropism 410 XXXVIII.--RESPONSE OF PLANTS TO WIRELESS STIMULATION. Effects of different rays of spectrum on growth--The wireless system--Mechanical and electrical responses of _Mimosa_ to Hertzian waves--Effect of wireless stimulation on growth of plants 416 XXXIX.--GEOTROPISM. Direction of the stimulus of gravity--The Geotropic Recorder--Determination of the character of geotropic reaction--Theory of statoliths--Determination of the latent period--The complete geotropic curve--Determination of effective direction of stimulus of gravity--Algebraical summation of effects of geotropic and photic stimulus-- Analogy between the effects of stimulus of light and of gravity--Relation between the directive angle and geotropic reaction--Differential geotropic excitability 425 XL.--GEO-ELECTRIC RESPONSE OF SHOOT.