Electric investigation shows that the lower half of the pulvinus of Mimosa is geotropically more excitable than the upper half.
[34] "Comparative Electro-Physiology," p. 20.
[35] For detailed account cf. Chapter XLIII.
[36] Haberlandt—Ibid—p. 598.
XLI.—THE MECHANICAL AND ELECTRICAL RESPONSE
OF ROOT TO VARIOUS STIMULI
By
Sir J. C. Bose.
In the last chapter we studied the electric response of the shoot to the stimulus of gravity, and found that the excitatory effect of that stimulus is similar to that of other forms of stimulation. Before taking up the subject of the geo-electric response of the root to gravitational stimulus, I shall describe the effects of other forms of stimuli on the mechanical and electrical response of the root.
In connection with this subject, it should be borne in mind that the responsive curvature in the root takes place in the sub-apical growing zone which is separated by a certain distance from the tip. The stimulus is therefore direct when applied at the responding growing region; it is indirect when applied at the tip of the root. The intervening distance between the root-tip and the responsive zone of growth is semi-conducting or non-conducting.