Edwardsiella tarda was found to produce two dermatonecrotic exotoxic substances for rabbit. These two toxins were functionally distinguished by their onsets of symptoms. The early reacting toxin was found to cause mainly erythema 3-8 hours after intracutaneous injection and this erythema lasted for three days. The late reacting toxin was found to cause oedema first and then necrotic erythema 5-7 days after injection. Both toxins were antigenic and their toxic functions were not observed in immune animals. Both toxins were suggested to be high molecular weight proteins by the following reasons. They were precipitated by ethanol. The early acting toxin precipitated mainly in 0-20% ammonium sulfate saturation and the late acting toxin precipitated mainly in 40-60% saturation. They were heat sensitive. They were sensitive to acid and alkaline treatment. Their activities were not reduced by chloroform treatment. The molecular weight of the early reacting toxin was found to be less than blue dextran and more than ferritin, and that of the late reacting toxin was found to be less than albumin.
