General superclustering.

It is noted that, in all, more than a dozen individual superclusters have been investigated in some detail. A table is included summarizing approximate data for nine. Some superclusters exhibit a pronounced filamentary structure, and it has been suggested (Einasto, 1983) that such filaments are the primary structure of all superclusters. Evidence is accumulating that at least some superclusters merge into one another, and Einasto has described the universe as having an irregular cellular structure, the cells being the empty or nearly empty voids in space and the superclusters being flat filamentary structures serving as interstices of matter between the voids. Numerical simulations based on the Zel'dovich model (Zel'dovich, 1978) indicate that the 'pancakes' eventually become filamentary and coalesce. However, owing to the irregular and filamentary nature of superclusters, all overlapping in projection, details of their structures remain elusive.