a1 Cameron College, Lawton, Oklahoma, 73501 U.S.A.
Several classes of topological spaces which are either the infimum or supremum of a family of metrizable topologies in the lattice of topologies were given by Anderson . In this paper we investigate the completion of the set of metrizable topologies in four distinct convergence structure lattices on an infinite set. We also observe the influence on these completions of the question regarding the existence of nonnormal ultrafilters which Čech  asserted could be neither provednor disproved using present mathematical axiom systems.
(Received November 15 1972)
(Revised March 16 1973)