Rhabdias bufonis which can be found plentifully in every toad intestine throughout the year, were employed in these experiments consisting in vitro and in vivo examinations. Experiment in vitro : Each group of five worms were put in drug solutions. The charges in their movement in the solution 'were recorded until the moving stopped, estimating the toxicities of the drugs to the worms. Experiment in vivo : The drugs were given toads per os. From the following day observations on the numbers of worms excreted from the toads were continued for six days. On the last day of the observations, these toads were dissected to see the pathological changes caused by diugs in the alimentary canal and other organs concerned. Twenty nine drugs were tested by this method. Some of them were effective in vitro experiment and others were effective in vivo experiment, while most popular anthelmintics were proved to be effective in both expeiments.
