Abstract
The factors responsible for stimulating activation of cystacanths ofPolymorphus minutus in vitrohave been investigated. Under the conditions used, the optimum temperature for activation was found to be 42–44 °C, at a pH of 7·0. A marked enhancement of activation rate was observed after preincubation in a 1 mM solution of sodium taurocholate and in solutions of sodium cholate, sodium glycocholate or sodium deoxycholate. This apparent effect of bile salts has been compared with that of other detergents, and a significant enhancement of activation rate above control was observed with saponin and sodium fusidate. Trypsin did not affect the rate of activation, and some inhibition occurred with lipase. The osmotic pressure of the surrounding medium has an effect on activation, the rate of which varies inversely with osmolarity. The conditions for activationin vitroare compared with those of the physicochemical environmentin vivo.