  The observations of bulge/disk segregation in the Universe are reviewed with
a focus on whether the observed segregation in clusters is local or global, and
whether there is bulge-disk segregation on large-scales. The high concentration
of bulge-rich galaxies in the cores of clusters of galaxies can be accounted
for by several popular physical processes: 1) biased early elliptical
formation, 2) abortion of disk formation by tidal destruction of the gas
reservoirs that fuel such disks, 3) ram pressure stripping of the gas in disks
by intergalactic gas, 4) merging of spiral galaxies into ellipticals (which is
the main focus of this review). A global scenario is outlined incorporating
each of these processes.
