THE EFFECT OF TEMPERATURE AND pH ON THE LONGEVITY OF SCHISTOSOMATIUM DOUTHITTI MIRACIDIA

Abstract

Observations made on the effect of various temperatures and hydrogen ion concentrations on the longevity of Schistosomatium douthitti miracidia showed both to be critical factors. The half-life of the miracidia varied from 1.5 hours at 35 °C to 11 hours at 8 °C, at a constant pH of 7.3. The effect of hydrogen ion concentration was less pronounced, the optimum being pH 7.5. A large population of miracidia from a single liver continued hatching over a 4-hour period with a peak output occurring at half an hour and another at 1 hour after exposure to water. The longevity of the miracidia hatching within the first hour exceeded that of the larvae hatching later.