Abstract
1. The post-synaptic action of efferent fibres on lateral line organs in the burbot was investigated with extracellular electrodes.2. Selective excitation of efferent fibres or stimulation of the lateral line nerve causes a negative efferent potential in the epithelium, an increase in the microphonic potential, and inhibition of afferent nerve impulses.3. Stimulation of the lateral line nerve causes antidromic impulses in the afferent fibres in addition to exciting the efferent fibres. However, stimulation of the lateral line nerve has no post-synaptic influence on lateral line organs when the efferent synapses are selectively blocked by gallamine.4. The influence of efferent stimulation on the microphonic potential is greater at large amplitudes of mechanical stimulation than at low.5. The similarities between the effects of efferent stimulation in the lateral line organ and in the cochlea suggest similar synaptic mechanisms.