Left panel: dust-to-total gas mass ratio as a function of the molecular-to-atomic gas mass ratio within r₂₅ for the gas sample. The small, transparent green circles and red squares are data points assuming a constant and a metallicity-dependent X_CO, respectively. These data points are drawn without error bars. The large symbols are the means of y-axis values in bins of x-axis values. Right panel: same as left panel, under the assumption of the constant X_CO and displaying data points as a function of morphological stage (four main bins in galaxy morphology).