Echinostome rediae: Effect of pretreatment with cold on transplantation to uninfected snails

When donor snails, Lymnaea stagnalis, infected with Echinoparyphium aconiatum were held at 13 C for at least 24 days, transplantation of newborn rediae from them to uninfected snails was 2.5 times as successful as when donor snails were held at 23 C. The difference does not seem to be do to the fact that rediae transferred from 13 C-snails were slightly larger than those from 23 C. This effect of temperature was not observed in analogous experiments with another echinostome, Isthmiophora melis. The mechanism of this phenomenon found in the experiments with E. aconiatum is still unknown.