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.

    57/332 page 631
    LIV. THE CIMTICAL ANGLE FOR GEO-ELECTRIC EXCITATION. By Sir J. C. Bose, Assisted by Satyendra Chandra Guha, m.sc. A new line of investigation will be described in the present chapter which will afford an independent and crucial test as regards the falling starch grains being the effective factor in geotropic excitation. The results, to be presently described, will be better understood if we visualise the process of the fall of the starch grains in consequence of the inclination of the organ to the vertical. Let us take a mechanical model in which a layer of sand particles are resting on a flat surface. On gradually increasing the inclination of the surface to the horizon, there will at first be no displacement of the particles; for on account of friction and cohesion they will remain sticking against the surface. During the continuous increase of the angle, a point will be reached when there will be an abrupt sliding down of the particles. This angle of sliding we shall designate as the critical angle ; it will be relatively high if the surface be rough, and low when the surface is smooth. Again a rough surface may be smoothed down by the repeated sliding down of the particles. The critical point may thus be lowered by repetition of the sliding process. c
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