Abstract
Unilateral, selective left-sided sectioning of the horizontal and vertical ampullar nerves was performed. After the operation, horizontal-rotatory nystagmus developed. When the cats were tilted around their longitudinal axis towards the operated ear, the horizontal nystagmus increased in intensity at the same time as the rotatory component disappeared. Tilling towards the non-operated ear increased the rotatory nystagmus and completely inhibited the horizontal component. The cause of this reaction is discussed.