Relative pool sizes of 32P-phosphate esters in phyllodia of Bryophyllum tubiflorum were determined. There were no indications that ATP and reduced pyridine nucleotides are accumulated during the light period, as was proposed by Nuernbergk (1961, 1962). The levels of F-1-6-P, G-6-P and F-6-P were nearly constant during the day and the night. The pool size of PGS increased rapidly when the phyllodia were transferred from light to dark and decreased when they were transferred from dark to light. The concentration of RuDP was in inverse ratio to that of PGS. The PEP pool decreased in the light period. Removal of CO2 during the dark period had no effect on the pool sizes of phosphate esters. © 1969 Springer-Verlag.