[Biophysical aspects on the result of the Spacelab experiment and consequences for Bárány's theory]

On testing the peripheral vestibular apparatus of astronauts with healthy labyrinths, nystagmus was observed when flushing the ears with hot or cold water even in the absence of gravitation. In the opinion of some scientists, this seems to refute Bárány's theory. They attempt to explain nystagmus as a result of compression. The hypothesis of Bárány, basing on terrestrial conditions, explains the peripheral impulse as the result of a convective flow caused by heating or cooling within the horizontal semicircular canal. However, if gravitation is absent any such circulation is excluded, because buoyancy is impossible without gravitation. The article shows, on the one hand, that the compression hypothesis cannot be correct, where as on the other Bárány's theory needs completion. For, in addition to the convective flow, the expansion of the endolymph resulting from heat must be considered. This effect occurs even in the absence of gravitation.