Life movements in plants / by Sir Jagadis Chunder Bose.

  • Jagadish Chandra Bose
Date:
1923
Catalogue details

Licence: In copyright

Credit: Life movements in plants / by Sir Jagadis Chunder Bose. Source: Wellcome Collection.

    291/332 page 865
    1. All forms of Direct stimuli induce contraction or retardation of growth, and Indirect stimuli expansion or acceleration of growth. 2. Unilateral stimulus induces a positive curvature by the contraction of the proximal, and expansion of the distal side. 3. Transverse conduction of excitation neutralises, or reverses the positive curvature. This effect is accentuated by the differential excitabilities of the upper and the under halves of the anisotropic organ. Excitation internally diffused induces effect similar to diffuse external stimulus. 4. The effect of rise of temperature is opposite to that of the stimulus of light. MECHANOTROPISM : TWINING OF TENDRILLS. It has been repeatedly shown that direct stimulations of all kinds induce contraction, and retardation of growth, while indirect stimulations cause an acceleration of the rate of growth (p. 291). Under unilateral mechanical stimulus of short duration, the directly stimulated proximal side of a tendril undergoes contraction, and the indirectly stimulated distal side shows the opposite effect of expansion ; a positive curvature is thus produced, with a movement towards the stimulus. The after-effect of direct stimulus is an accelera- tion of growth above the normal, hence after brief unilateral stimulation, the stimulated side undergoes an acceleration of growth and expansion, by which the recovery is hastened (p. 300). This positive after-effect of stimulus on growth is seen in the balanced record o1 growth (p. 325). Stimulation of one side of the tendril induces an expansion of the opposite side (effect of indirect stimulus), even in cases where the contractility of the stimulated side is feeble. Hence response to direct stimulation of the more excitable side of
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