The mode of action of carbon tetrachloride on Fasciola hepatica.

1. A biliary fistula was prepared in twelve sheep.2. Each animal was given 2 ml. of (14)C-carbon tetrachloride (specific activity 15 mc/m-mole) and bile collected at 2, 4, 24 and 48 hr.3. Specific activity was measured by liquid scintillation counting before and after each specimen had been heated to 75 degrees C for 10 min to drive off volatile content (carbon tetrachloride).4. Only traces of activity were present in the bile and heating did not alter this.5. There was no difference in the survival times of adult Fasciola hepatica incubated in Hedon Flieg medium with and without 25% bile from non-medicated sheep, or with carbon tetrachloride in a concentration of 0.03%, but 25% of bile from sheep given 2 ml. of carbon tetrachloride 24 hr before greatly increased lethality in vitro.6. The anthelmintic action of carbon tetrachloride on F. hepatica does not result from a direct action due to excretion in bile of unchanged carbon tetrachloride but of an unidentified toxic element not necessarily derived from the drug but which arises as a result of its administration.