Abstract
1. The phosphatases present in the adult and cysticercus stages ofTaenia pisiformishave been investigated using histochemical and biochemical methods.2. Histochemical tests failed to demonstrate the sites of enzyme activity in the cysticercus.3. In the adult, the acid phosphatase is confined to the cuticle. Alkaline phosphatase occurs in the cuticle, subcuticular cells and the membranes bounding the ovary and vitelline tubules.4. The histochemical distribution is uneven along the length of the worm, both acid and alkaline phosphatase being predominant hi the region of ‘mature’ proglottides. The scolex was negative to both tests.5. Biochemical tests have demonstrated distinct acid and alkaline phosphatases in the cysticercus and adult stages. In the cysticercus the acid enzyme is predominant and in the adult it is the alkaline, implying a change in relative magnitude during the completion of the life cycle.6. pH-activity curves have been obtained for the enzymes of both stages.7. The results are discussed in relation to recent findings in the field of cestode enzymology, and it is suggested that these phosphatases may be associated with active transport of materials across the cuticle and ovarian and vitelline membranes.