Studies will continue on synaptic transmission in various in vitro preparations. Specifically, the role of calcium in transmitter release will be studied by incorporating a calcium ionophore into the presynaptic nerve terminal membrane and loading the presynaptic terminal with calcium and other divalent ions by means of the ionophore. The effects of lateral spinal cord destruction on vesicle distribution in Muller axons of the lamprey spinal cord will be examined. Studies will be continued on the nature and voltage dependence of the conductance changes in eel electroplaques produced by acetylcholine.