The Activity of the Horizontal Semicircular Canal of the Dogfish, Scyllium Canicula

Abstract

1. Oscillographic records from the horizontal ampulla of the dogfish show: (a) A spontaneous discharge of impulses when the fish is stationary in the normal position. (b) An increased discharge during ipsilateral rotation. (c) A diminution of the spontaneous discharge during contralateral rotation. (d) A prolonged after-discharge on stopping contralateral rotation. 2. The threshold for the responses is an angular acceleration of the order of 11° per sec². 3. This mechanism provides a means of signalling to the centre equal and opposite phases of a biphasic physical change. 4. The two opposite ampullae work antagonistically, and the reflex responses of the normal fish depend upon the balance of the afferent discharges from the left and right labyrinths.