EWALD, in 1892, reported the results of his experiments with pigeons on the physiology of the semicircular canals.* As a result of these experiments two physiologic laws were formulated, and, as expressed in Morrison's textbook,3 are as follows: First, the horizontal semicircular canal gives a maximal response by movement of its endolymph toward its ampulla, while the reverse is true of the vertical semicircular canals. Second, when a canal is maximally stimulated, there results a nystagmus to the same side. Therefore, stimulation of the vestibular end-organ results from movement of the endolymph in the semicircular canal, which causes a bending of the cilia of the vestibular end-organ cells of the crista ampullaris.3 Ewald's law suggests that when the cilia of the horizontal semicircular canal are bent by a flow of endolymph toward its ampulla, maximal stimulation results. After this, Bárány observed clinically in the turning test, in stimulating