Abstract
Fasciola metacercariae were allowed to encyst on rice straws and polyethylene sheets left in the field in Sendai in August. They retained their infective capacity when examined in November and September, respectively. The same experiment was performed in December, and the metacercariae were found to maintain their infective power until April and February of the following year, respectively. In both experiments mice were used to examine infective power of the fluke every month.
