Abstract
1 An invitro preparation of Fasciola hepatica is described which responded to electrical stimulation with tetanic spasms. Both carbon tetrachloride (20-500 nl/ml), and its metabolite chloroform (50-1000nl/ml), produced contractions in the preparation which extinguished the responses to electrical stimulation. It is suggested that the spasmogenic action of carbon tetrachloride and its metabolite may contribute to the fasciolifugal action of the drug. 2 Hexachloroethane, another fasiolifuge, had very little effect in the preparation. However, pentachloroethane and tetrachloroethylene, the main products of the metabolism of hexachloroethane in sheep, were potent spasmogens in preparations of Fasciola hepatica. Pentachloroethane was about twice as potent as carbon tetrachloride. 3 Tetrodotoxin (2mug/ml) did not antagonize the responses of the preparation to electrical stimulation of carbon tetrachloride.