Thus while the effect of direct unilateral stimulation is a positive curvature, the effect of indirect stimulation is a negative curvature. The following table gives a summary of results of tropic effects under unilateral application of indirect stimulus. TABLE XXIII.--SHOWING TROPIC EFFECT OF UNILATERAL APPLICATION OF INDIRECT STIMULUS. +------------------------------------------------------------+ |Stimulus. | Character of intervening | Sign of tropic | | | tissue. | response. | +----------+---------------------------+---------------------+ | Moderate | Conducting | Positive curvature. | | " | Semi-conducting | Negative followed | | | | by positive. | | Feeble | Semi-conducting | Negative Curvature. | | Moderate | Non-conducting | " " | +----------+---------------------------+---------------------+ |Direct application of unilateral stimulus induces a positive| |curvature. | +------------------------------------------------------------+ SUMMARY. In sensitive plants stimulus applied at a distance induces in the responding region an expansion indicative of increase of turgor. The effect of indirect stimulation is also exhibited by an electric change of galvanometric positivity, indicative of enhancement of turgor and expansion. Indirect stimulus induces in growing organs an enhancement of rate of growth. Unilateral application of stimulus causes an expansion higher up on the same side to which the stimulus is applied; the result is an induced convexity, a movement away from the stimulus, _i.e._, a negative curvature. Direct stimulus applied unilaterally at the responding region induces, on the other hand, a positive curvature. XXV.--TROPIC CURVATURE WITH TRANSVERSE TRANSMISSION OF EFFECT OF STIMULUS _By_ SIR J. C. BOSE, _Assisted by_ GURUPRASANNA DAS. We have next to consider a very large class of phenomena arising out of the direct stimulation of one side and its transversely transmitted effect on the opposite side. The unilateral stimuli to which the plant is naturally exposed are those of contact, of light, of thermal radiation, and of gravity. There is besides the stimulation by electric current. I shall presently show that these tropic curvatures are determined by the definite effects of direct and indirect stimulations.