XXVII.—ON GALVANOTROPISM
By
Sir J. C. Bose,
Assisted by
Guruprasanna Das.
Before describing the effect of unilateral application of an electrical current in inducing tropic curvature, I shall give an account of the polar effect of anode and cathode on the pulvinated and growing organs. In my previous work[6] on the action of electrical current on sensitive pulvini I have shown that:—
(1) at the 'make' of a current of moderate intensity a contraction takes place at the cathode; the anode induces no such contractile effect;
(2) at the 'make' of a stronger current both the anode and cathode induce contraction.
I have also carried out further investigations on the polar effect of current on the autonomous activity of the leaflet of Desmodium gyrans. These rhythmic pulsations can be recorded by my Oscillating Recorder. Each pulsation consists of a sudden contractile movement downwards, corresponding to the systole of a beating heart, and a slower up movement of diastolic expansion. Application of cathode at the pulvinule was found to exert a contractile reaction, exhibited either by the reduction of normal limit of diastolic expansion, or by an arrest of movement at systole. The effect of anode was precisely the opposite; the induced expansion was exhibited either by reduction of normal limit of systolic contraction, or by arrest of pulsation at diastole.
From the above results it is seen that with a feeble current:
(1) contraction is induced at the cathode, and
(2) expansion is brought about at the anode.
These effects take place under the action of a feeble current. Under strong currents, contraction takes place both at the anode and the cathode.