Up until now, it has been visualized that the membrane systems of an eukaryotic cell include a limiting plasma membrane and separated organelles in the cytoplasm. They all constitute the cell.The presence of a wide variety of experimental results which suggest that a united membrane constitutes the cell has therefore necessitated this morphological study.To visualize the cell, the new tissue preparation technique introduced by Artvinli (1975), and the stains reacting or combining with chemical groups contained in biomolecules of the membranes as well as of the cytoplasm have been used. Light and electron microscopic appearance of the cell, under these conditions, is similar to a network. The cell was therefore defined as a membranous network. Its structure can also be visualized as a biomolecular network.The existence of such a united membrane or a biomolecular network seems to be true since it could be predicted and also confirmed by reviewing of the literature.Such a structure of the cell links any part of the cell to its other parts, and can control metabolism through changes which occur in its shape, in other words, interdependent changes in conformations of biomolecules.