2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/6819The amount, timing and ultimate location of mass transfer and induced star formation in galaxy collisions are sensitive functions of orbital and galaxy structural parameters. I discuss the role of detailed case studies and describe the results for two systems, Arp 284 and NGC 2207/IC 2163, that have been studied with both multiwaveband observations, and detailed dynamical models. The models yield the mass transfer and compressional histories of the encounters and the ``probable causes'' or triggers of individual star-forming regions.6 pgs., 2 figs., for Proceedings of IAU 217, Recycling intergalactic and interstellar matter, eds. P.-A. Duc, J. Brane, and E. BrinksAstrophysicstext