The electrical signals propagated through the ectodermal epithelium of Cordylophora lacustris (the Josephson pulses) were recorded as transepithelial action potential-like events. Experiments on the ionic basis of electrogenesis of these action potentials suggested that they result from an outward flow of chloride ions from the ectodermal cells into the enteron. Further evidence for this hypothesis came from measurements of the ionic concentrations in the tissues of Cordylophora, which showed that these cells have unusually high levels of chloride. Chloride dependent electrogenesis allows this excitable system to function in media of low and variable ionic strength, which are a typical feature of this organism's natural environment.

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