  We present line strengths in the bulges and inner disks of 38 galaxies in the
local universe, including several galaxies whose bulges were previously
identified as being disk-like in their colors or kinematics, to see if their
spectral properties reveal evidence for secular evolution. We find that red
bulges of all Hubble types are similar to luminous ellipticals in their central
stellar populations. They have large luminosity-weighted ages, metallicities,
and alpha/Fe ratios. Blue bulges can be separated into a metal-poor class that
is restricted to late-types with small velocity dispersion and a young,
metal-rich class that includes all Hubble types and velocity dispersions.
Luminosity-weighted metallicities and alpha/Fe ratios are sensitive to central
velocity dispersion and maximum disk rotational velocity. Red bulges and
ellipticals follow the same scaling relations. We see differences in some
scaling relations between blue and red bulges and between bulges of barred and
unbarred galaxies. Most bulges have decreasing metallicity with increasing
radius; galaxies with larger central metallicities have steeper gradients.
Where positive age gradients (with the central regions being younger) are
present, they are invariably in barred galaxies. The metallicities of bulges
are correlated with those of their disks. While this and the differences
between barred and unbarred galaxies suggest that secular evolution cannot be
ignored, our results are generally consistent with the hypothesis that mergers
have been the dominant mechanism responsible for bulge formation.
