Star formation efficiency (SFR/M_Gas) versus the gas fraction (M_Gas/M_Baryon) for galaxies of different morphological types and both within the Virgo cluster (top) and the field (bottom). The blue and red lines are linear fits of slope −1 to the late (Sc/Sd and Sm/Irr) and early (E/S0) type galaxies for Virgo (dotted) and Field (dashed) respectively. The black curved lines are second order polynomial fits to the late types, in this case later than Sa, again Virgo (dotted) and Field (dashed).