Loeb, J. (1905). Geotropism in animals. In J. Loeb, The decennial publications second series: Vol. 15. Studies in general physiology, part 1 (pp. 176-190). Chicago, IL, US: University of Chicago Press.
http://dx.doi.org/10.1037/13682-005
I wish to give in the following pages some further facts which show that certain animals are compelled to orient their bodies in a definite way toward the center of the earth, as are certain plants. Topics include geotropic curvatures in animals; geotropism in free-swimming animals and its significance for the bathometric distribution of certain pelagic animals; and the geotropism of higher animals and its dependence upon the inner ear. (PsycINFO Database Record (c) 2016 APA, all rights reserved)