_Effect of anode: Experiment 112._--If the cathode induced a retardation, the anode might be expected to induce an acceleration of growth. But in my first experiment on the action of anode, I could detect no perceptible variation of rate of growth. In trying to account for this failure, I found that the specimen employed for the experiment had normally a very rapid rate of growth. It appeared that an induced acceleration would be brought out more conspicuously by choosing a specimen in which the growth-rate was low, rather than in one in which it was near its maximum. Acting on this idea, I took another specimen of _Kysoor_ in which the normal rate was as slow as 0·10 µ per second. On applying the anode to the growing region, there was an enhancement to one and half times the normal rate (Fig. 108). TABLE XXVIII.--EFFECT OF ANODE AND CATHODE ON GROWTH (_Kysoor_). Specimen A Normal rate 0·10 µ per sec. Acceleration under anode 0·155 µ per sec. Specimen B Normal rate 0·48 µ per sec. Retardation under cathode 0·14 µ per sec. The effects given above take place under the action of a feeble current. Strong current on the other hand induces a retardation or an arrest of growth. I have in the above experiments demonstrated the normal effect of anode in inducing expansion and acceleration of rate of growth; the cathode was shown to induce contraction and retardation of growth. Unilateral application of anode and cathode thus induces appropriate curvatures in pulvinated and in growing organs. SUMMARY. The effects of an electric current on growth is modified by the direction of current. A feeble anodic current enhances the rate of growth; a cathodic current on the other hand induces a retardation of the rate. Strong current, both anodic and cathodic, induces a retardation. XXVIII.--ON THERMONASTIC PHENOMENA _By_ SIR J. C. BOSE, _Assisted by_ SURENDRA CHANDRA DAS. In describing thermonastic curvatures Pfeffer says that "a special power of thermonastic response has been developed by various flowers, in which low temperatures produce closing movements, and high temperatures, opening ones. The flowers of _Crocus vernus_ and _Crocus luteus_ are specially responsive, as also those of _Tulipa Gesneriana_ for these flowers perceptibly respond to a change of temperature of half a degree centigrade."[7] [7] Pfeffer--_Ibid_, Vol. III, p. 112. We have hitherto studied the response of various organs to _stimulus_; we have now to deal with the effect of thermal variation. Does rise of temperature act like other forms of stimuli or is its action different? We have therefore to find: (1) The physiological effect of variation of temperature. (2) Whether thermonastic irritability is confined only to certain classes of organs, or is it a phenomenon of very wide occurrence?