“…The aliesterases of serum and brain were determined with a 0-2% (v/v) emulsion of tributyrin stabilized with 0-1% gum acacia (final concentrations). Although the activities of these two ali-esterases are measured in the same way, it should be noted that the ali-esterase of serum is a different enzyme from that found in brain Mendel, Myers, Uyldert, Ruys & Bruyn, 1953;Myers & Kemp, 1954). The cholinesterases present in serum, on the other hand, appear to be identical with those found in other tissues (Ord & Thompson, 1952;Myers, 1953;Davison, 1953).…”