Page:Researches on Irritability of Plants.djvu/43

of the vertical rod, either in the right-hand or the left-hand direction. By this means it is possible to bring the

Fig. 4.—General view of the whole apparatus, and the electrical connections by means of which excitatory shock of a definite duration may be given to the plant; duration of shock determined by metronome which completes electrical circuit. (From a Photograph.)

plane of movement of the writing-index exactly parallel to that of the writing-surface. The complete apparatus for