Upon a surface inclined at angle α Asterina gibbosa orients upward during negatively geotropic creeping until the average angle (θ) of the path is such that Δ sin θ/Δ sin α = const. This is true also in positively geotropic movement. The direction of orientation may be temporarily reversed by mechanical disturbance. The variation of θ is greater at low slopes. Tests with directed impressed pulls, due to an attached cork float, show that the pull upon the tube feet is of primary consequence for the determination of θ. When the component of gravitational pull in the direction of movement reaches a fraction of the total pull which is proportional to the gravitational vector parallel to the surface, the laterally acting component is ineffective. On this basis, it follows that Δ sin θ/Δ sin α = const.
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20 May 1935
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May 20 1935
THE GEOTROPIC RESPONSE IN ASTERINA
W. J. Crozier
W. J. Crozier
From the Laboratory of General Physiology, Harvard University, Cambridge, Massachusetts, and the Station Biologique, Roscoff, Finistère, France
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W. J. Crozier
From the Laboratory of General Physiology, Harvard University, Cambridge, Massachusetts, and the Station Biologique, Roscoff, Finistère, France
Accepted:
August 09 1934
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright, 1935, by The Rockefeller Institute for Medical Research
1935
J Gen Physiol (1935) 18 (5): 729–737.
Article history
Accepted:
August 09 1934
Citation
W. J. Crozier; THE GEOTROPIC RESPONSE IN ASTERINA . J Gen Physiol 20 May 1935; 18 (5): 729–737. doi: https://doi.org/10.1085/jgp.18.5.729
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