The adult worm and plerocercoid larva(sparganum) of Diphyllobothrium mansoni and Moniezia expansa employed in this experiment. The adult worms were divided into three portions, i.e. immature, mature and gravid proglottids, and each proglottids were incubated in 50 cc or 250 cc volume of special incubation flasks with incubation medium consisting of 10 cc of 25 cc of Krebs-Ringer phosphate buffer (pH 7.4). The incubation medium was added C(14)-acetate and non-radioactive carrier Na-acetate so as to contain acetate concentration of 50 mg per cent. The worms were allowed to incubate for 5 hours in the Dubnoff metabolic shaking incubator at 38 C. After incubation period, the lactate and pyruvate appearance rate, total CO(2) production tate, the turnover rates were employed as pervious report(Seo et al., 1965). The quantitative analysis of C(14)-acetate utilized by the adult worm and plerocercoid larva of D. mansoni and M. expansa were compared and discussed in this report. According to these data of the experiment, it is impressed that the fatty acid such as acetate may play a role of major part of their metabolism in the adult worm and plerocercoid larva of D. mansoni , whereas minor part of acetate participated in the metabolism by M. expansa.
