[The significance of slow flows for the caloric excitability of the vestibular organs in weightlessness].

Bárány's theory of caloric nystagmus is based on the assumption of fluid convection in the perilymph. It was a great surprise that caloric nystagmus could be demonstrated in weightlessness as well, i.e. under conditions in which thermoconvection cannot occur because of loss of gravity. This phenomenon was explained by different theories, each of which is bound to certain assumptions. Experimental investigations and mathematical approaches concerning fluid mechanics of the endolymph under calorisation, indicate that creeping flow must be an important factor. This flow--not taken into consideration so far--may explain caloric nystagmus in weightlessness as well as some difficult problems in caloric excitability on farth.