Determination of the activity of choleragen on tadpoles

A method of titration of choleragen in tadpoles ofRanatemporaria is suggested. Unlike in methods known hitherto, the animals are kept (10 at a time) in vessels with water containing serial dilutions of choleragen. The degree of activity of the choleragen is determined from the percentage of dying animals. The dilution of cholergen causing death of 50% of tadpoles after 24 h was taken as the unit of activity. The method is simple, accurate, easily reproducible, and economical in use.