[Determination of choleragen activity in tadpoles]

A method of titration of the V. cholerae toxin obtained from the broth culture filtrates is presented. In difference from the earlier methods, the larvae of Rana temporaria were used as a test object. The tadpoles were placed in the vessels with water containing graded concentrations of the toxin. The titer of the toxin activity was evaluated by the percentage of dead tadpoles. The concentration causing the death of 50 per cent of the tadpoles in the course of the 24 hours was taken as a unit of toxin activity. The method is simple, easily reproducible and economical.