Personally I believe that circumnutation is automatic--is primarily due to internal stimuli. It is however in some way connected with gravitational sensitiveness, since the movement normally occurs round a vertical line. It is not unnatural that, when the plant has no external stimulus by which the vertical can be recognised, the revolving movement should be upset.英文原著 · 《Darwin and Modern Science》
It was however the question of the localisation of the gravitational sense in the tip of the seedling root or radicle that aroused most attention, and it was on this question that a controversy arose which has continued to the present day.英文原著 · 《Darwin and Modern Science》
The chemical change in the root can be detected before any curvature has occurred and must therefore be a symptom of stimulation, not of movement. It is particularly interesting to find that the change in the root, on which Czapek's test depends, takes place in the tip, i.e. in the region which Darwin held to be the centre for gravitational sensitiveness.英文原著 · 《Darwin and Modern Science》
There can I think be little doubt but that Jeans is right in looking to gravitational instability as the primary cause of fission, but when we consider that a binary system, with a mass larger than the sun's, is found to rotate in a few hours, there seems reason to look to rotation as a contributory cause scarcely less important than the primary one.英文原著 · 《Darwin and Modern Science》
Like without that gravitational pull you'll go flying off into nothingness.美剧 · 《Billions》
Afraid, if you ever do something even remotely selfish, the earth's gravitational pull will end and we'll all go flying into space?美剧 · 《Shameless》
We've been corresponding for years about our mutual interest in Gravitational wave signatures of inflatons in the early universe.美剧 · 《The Big Bang Theory》