  We have tested for luminosity, colour and morphology dependence of the degree
of filamentarity in seven nearly two dimensional strips from the Sloan Digital
Sky Survey Data Release Four (SDSS DR4). The analysis is carried out at various
levels of coarse graining allowing us to address different length-scales. We
find that the brighter galaxies have a less filamentary distribution than the
fainter ones at all levels of coarse graining. The distribution of red galaxies
and ellipticals shows a higher degree of filamentarity compared to blue
galaxies and spirals respectively at low levels of coarse graining. The
behaviour is reversed at higher levels of coarse graining. We propose a picture
where the ellipticals are densely distributed in the vicinity of the nodes
where the filaments intersect while the spirals are sparsely distributed along
the entire extent of the filaments. Our findings indicate that the regions with
an excess of ellipticals are larger than galaxy clusters, protruding into the
filaments. We have also compared the predictions of a semi-analytic model of
galaxy formation (the Millennium Run galaxy catalogue) against our results for
the SDSS. We find the two to be in agreement for the $M^{*}$ galaxies and for
the red galaxies, while the model fails to correctly predict the filamentarity
of the brighter galaxies and the blue galaxies.
