1. The glucose uptake rate by plerocercoid of Diphyllobothrium sp. was a mean value of 5.35±0.80 µM/hr/g of wet wt, and total CO₂ production rates by the plerocercoid larva averaged 7.54±0.73 µM/hr/g of wet wt. The relative specific activity into respiratory CO₂ showed a mean value of 7.30 ±0.90 per cent. The rate of CO₂ production derived from medium C¹⁴-glucose was a mean of 0.58±0.13 µM/hr/g of wet wt. Therefore, the average value of 1.92±0.38 per cent of glucose utilized by the larvae from the medium C¹⁴-glucose was oxidized to respiratory CO₂.

2. The tissue concentration of glycogen in plerocercoid larva was a mean of 46.28 ±2.23 mg/g or 4.63±0.22 per cent/g of wet wt., and the turnover rate of glycogen pool was a mean of 0.049 ± 0.012 %/hr or 0.010 ± 0.003 mg/hr/g of wet wt. The average value of 2.76±1.00 per cent of glucose utilized by the larvae from the medium C¹⁴-glucose was incorporated to the glycogen.

3. These data accounts for that only 5 per cent of the utilized glucose by the plerocercoid larvae participated in furnishing the oxidation into respiratory CO₂ and the synthetic process into glycogen.