Once plant life invaded the land it was subject to the action of gravity, and geotropism ( "earth-turning" G), involving an automatic and adaptive response to gravity, was developed.    From Wordnik.com.  [The Human Brain]

But atavistic, or vestigial, geotropism in Genesistrine -- or a million larvae start crawling, and a million little frogs start hopping -- knowing no more what it's all about than we do when we crawl to work in the morning and hop away at night.    From Wordnik.com.  [The Book of the Damned] Reference

Thus I am now observing something about geotropism, and I had no idea a few weeks ago that this would have been necessary.    From Wordnik.com.  [More Letters of Charles Darwin — Volume 2] Reference

They give the quintessence of laboratory experiments as to what are the effects of different energies such as light (heliotropism), electricity (galvanotropism), gravity (geotropism), etc., in their reaction and influence upon the movements and actions of living organisms.    From Wordnik.com.  [Manhood of Humanity.] Reference

Projects included constructing an electron accelerator, making amino acids, photographing air currents, measuring the metabolic rate of small animals, extracting antibiotics from soil, culturing aquatic insects, tracking satellites, constructing an atom smasher, extracting the growth substances from a cantaloupe, conducting maze experiments with cockroaches, making an electrocardiogram of a water flea, constructing a Foucalt pendulum, and experimenting with geotropism.    From Wordnik.com.  [Boing Boing] Reference