Recent redshift surveys of the Nilson-, Zwicky-, and ESO-Uppsala galaxy catalogues revealed that the bright galaxies in these catalogues follow a spatial distribution where large empty regions are surrounded by sheet-like structures of galaxies and clusters (e.g. Giovanelli & Haynes 1991). From an observer's point of view, one may simply ask if the voids in the above-mentioned galaxy maps are real or if they reflect special observational selection effects, e.g. in surface brightness, integral magnitude or diameter. These catalogues contain many bright galaxies (MB
B), but only very few faint objects (MB ≥ M∗B
). Older work on the distribution of intrinsically faint galaxies, like irregular dwarfs, claimed that the dwarfs follow the distribution which is outlined by the giant galaxies.