SYNOPSIS.Whole cells ofPolytoma obtusumdo not utilize glucose or other hexoses, but cell‐free extracts show glucokinase activity having a pH optimum at 8.5 and a Q10of 2.4 between 0–20°C. Lack of glucom utilization by whole cells reflects a permeability barrier to all sugars.To determine whether inability of acetate‐grown cells to utilize butyrate also denoted a permeability barrier, permeability to acetate and butyrate was studied in acetate‐ and butyrate‐grown cells However, acetate‐grown cells accumulated C‐14 labeled butyrate against a concentration gradient. Therefore inability of acetate‐grown cells to utilize butyrate does not denote a permeability barrier.Acetate‐kinase activity was consktently demonstrated in cell‐free extracts of both acetate‐ and butyrate‐grown cells. Butyrate kinase was consistently found only in butyrate‐grown cells. However, the absence of buttymte kinase in acetate‐grown cells cannot be claimed since occasionally butyrate kinase activity was demonstrated in ext