Experimental Observations on Optokinetic Nystagmus in Respect of the Statocysts in the Crab

Abstract

For the investigation of the effect of the otolith system on optokinetic nystagmus, the crab was examined using an optical cylinder. The results obtained were as follows: (1) Optokinetic nystagmus always occurred with the stimulation of the optical cylinder. (2) In crabs of which statocysts were removed, the nystagmus was depressed. (3) The nystagmus was not depressed by forward position but depressed by backward position. (4) The nystagmus directed to the right side was depressed by right lateral position but not depressed by left lateral position. Similar findings were observed in cases of nystagmus directed to the left side. Analyzation of the results indicated that the otolith system has a certain effect on optokinetic nystagmus.