  We present the results of the study of the morphology and galaxy content of
the Sloan Great Wall (SGW). We use the luminosity density field to determine
superclusters in the SGW, and the fourth Minkowski functional V_3 and the
morphological signature (the K_1-K_2 shapefinders curve) to show the different
morphologies of the SGW, from a single filament to a multibranching, clumpy
planar system. The richest supercluster in the SGW, SCl~126 and especially its
core resemble a very rich filament, while another rich supercluster in the SGW,
SCl~111, resembles a "multispider" - an assembly of high density regions
connected by chains of galaxies. Using Minkowski functionals we study the
substructure of individual galaxy populations determined by their color in
these superclusters. We assess the statistical significance of the results with
the halo model and smoothed bootstrap. We study the galaxy content and the
properties of groups of galaxies in two richest superclusters of the SGW,
paying special attention to bright red galaxies (BRGs) and to the first ranked
galaxies in SGW groups. About 1/3 of BRGs are spirals. The scatter of colors of
elliptical BRGs is smaller than that of spiral BRGs. About half of BRGs and of
first ranked galaxies in groups have large peculiar velocities. Groups with
elliptical BRGs as their first ranked galaxies populate superclusters more
uniformly than the groups, which have a spiral BRG as its first ranked galaxy.
The galaxy and group content of the core of the supercluster SCl~126 shows
several differences in comparison with the outskirts of this supercluster and
with the supercluster SCl~111. Our results suggest that the formation history
and evolution of individual neighbour superclusters in the SGW has been
different.
