  Careful inspection of large-scale photographs of Shapley-Ames galaxies seems
to show a smooth transition between the morphological characteristics of
galaxies located on the narrow red, and on the broad blue, sequences in the
galaxian color-magnitude diagram. In other words there does not appear to be a
dichotomy between blue and red galaxies. Both the colors and the morphologies
of galaxies are found to correlate strongly with their environments. Red and
early-type Shapley-Ames galaxies are dominant in clusters, whereas blue
late-type star forming objects dominate the general field. Interestingly the
colors and morphologies of galaxies in small groups resemble the field and
differ from those in clusters. As noted by Baade the presence of dust and star
formation are very closely correlated, except in a few galaxies that probably
had unusual evolutionary histories. Over the entire range from S0 to Sc there
is no significant difference between the integrated colors of normal and barred
objects suggesting that the formation of a bar does not significantly affect
the stellar evolutionary history of a galaxy.
