On the Exceptional Position of the Auditory Sphere

The course of the following considerations was determined by a suggestion arising from a somewhat remote department of the physiology of the senses. Josef Breuer was the first to put forward the suggestion (in 1874), which was later fully established, that the otolith apparatus of the lower animals does not serve the function of hearing, as was formerly supposed, but the perception of the movement and position of the body relative to its environment and orientation in space.1 Earlier still it had been observed that certain crustaceans, whose otocysts open to the exterior through a crack and contain small foreign bodies as otoliths, lose these together with the shell at every moult, after which they introduce new ones, being quite indifferent to what material is offered to them for the purpose. The creatures feel around eagerly on the floor of the aquarium with their claws and fill the otocysts with grains of sand or the like, which they have picked up.

With the intention of settling the question, beyond all dispute, of the function of these organs, the otocysts (or statocysts as they have been more correctly named since then), the Viennese physiologist, A. Kreidl, following a suggestion of Exner, induced the crustacean Palæmon to take up iron-dust into its statocysts.2 So statoliths were formed which were subject to magnetic influence. When he approached such an animal with a strong electro-magnet from the dorsal side, the statoliths were lifted up on to the dorsal wall of the statocysts, thereby taking up the same position as they would occupy in a normal animal which had fallen on its back. Just like such an animal, accordingly, the crustacean which had been magnetised turned itself over and remained lying on its back, for when it was in