The membranous labyrinth lies ('neloHed in the very hard petroua part, of the temporal bone and, as the name implies. it, s structure is extremely compl('x. This may explain why our knowledge of this organ and the vestibular sensory regions within it, is not yet satisfactory. In recent years the rapid development of space research has provided a power- ful stimulus to our interest in the vestibular apparatus. This has found expression in annual symposia, in which the role of thc vestibular organs in the exploration of space is discussed. However, little is known as yet about the inflU