I will first give a diagrammatic view of the different parts of the apparatus which I devised for this investigation.[1] The leaf of Mimosa is attached to one arm of a light aluminium lever, L, by means of thread. At right angles to the lever is the writing index W, which traces on a smoked glass plate allowed to fall at a definite rate by clockwork the responsive movement of the leaf. Under a definite stimulus of electric shock the leaf falls down, pulling the lever L, and moving the writer towards the left. (Fig. 14.) The amplitude of the response-curve
Fig. 14. Diagrammatic representation of the complete apparatus for determination of diurnal variation of excitability. Petiole of Mimosa, attached by thread to one arm of lever L; writing index W traces on smoked glass plate G, the responsive fall and recovery of leaf. A, primary, and S, secondary, of induction coil. Exciting shock passes through the plant by electrodes E, E. A, accumulator. C, clockwork for regulating duration of tetanizing shock. Primary circuit of coil completed by plunging rod, V, dipping into cup of mercury M.
- ↑ See also Bose.—The Diurnal Variation of Moto-excitability in Mimosa—Annals of Botany, Oct. 1913.
