The growth temperature of the axenic strain of Dictyostelium discoideum, Ax-2, influences its subsequent rate of development. Despite the fact that many other microorganisms exhibit homeoviscous adaptation in response to temperature, the altered rates of D. discoideum development are not due to a response to modified membrane fluidity. Growth temperature does not affect the fluidity of the cell membranes as determined by electron paramagnetic resonance and there are no systematic temperature dependent variations in fatty acid composition or sterol:phospholipid ratio.