Gas mass relative to the initial value contained within a spherical volume of radius ﹩r=0.03﹩ grid units (about 3 kpc) about the centers of the Hydra model galaxies as a function of time. Solid curves are for the galaxies A and B (as labeled) in the best model. Dotted curves show the fractional gas mass around each center that was transferred from the other galaxy in the model. The curve with plus signs shows mass transferred to B from A, while the curve with circles shows transfer to A from B. The vertical dotted line shows the approximate time of closest approach.