The upward geotropic orientation of young rats can be described by simple mathematical expressions (Crozier and Pincus, 1926, 192627, a, b; Pincus, 1926-27). In essence these formulae also apply precisely for the geotropism of invertebrates (Wolf, 1926-27; Crozier and Stier, 1927-28; Wolf and Crozier, 1927-28). I t seemed important to repeat with young mice the initial experiments with rats (Cr...
