Page:Life Movements in Plants.djvu/145

The scope of investigation will be best described according to the following plan^[1]:—

PART I.—INFLUENCE OF DIRECTION OF ELECTRIC CURRENT ON CONDUCTION OF EXCITATION IN PLANTS.

General method of experiment.

Effect of feeble currant on velocity of transmission of excitation 'up-hill' or 'down-hill.'

Determination of variation of conductivity by the method of minimal stimulus and response.

The after-effect of current.

PART II.—INFLUENCE OF DIRECTION OF ELECTRIC CURRENT ON CONDUCTION OF EXCITATION IN ANIMAL NERVE.

The method of experiment.

Variation of velocity of transmission under the action of current.

Variation in the intensity of transmitted excitation.

PART I.—INFLUENCE OF DIRECTION OF CURRENT ON TRANSMISSION OF EXCITATION IN PLANT.

THE METHOD OF EXPERIMENT.

I may here say a few words of the manner in which the period of transmission can be found from the record given by my Resonant Recorder, fully described in my previous paper. The writer attached to the recording lever of this instrument is maintained by electromagnetic means in a state of to-and-fro vibration. The record thus consists of a series of dots made by the tapping writer, which is tuned to vibrate at a definite rate, say, 10 times per second. In a particular case whose record is given in Curve 1 (Fig. 46), indirect stimulus of electric stock was applied at a distance of 15 mm. from the responding

1. For fuller account see Bose—'The influence of Homodromous and Heterodromous Electric Current on Transmission of Excitation in Plant and Animal.' Proc. R. S. B., Vol. 88, 1915.