what is cell theory consist of
Definition: The Cell Theory is one of the basic principles of biology. Credit for the formulation of this theory is given to German scientists Theodor Schwann, Matthias Schleiden, and Rudolph Virchow. The Cell Theory states: 1  All living organisms are composed of cells. 2  They may be unicellular or multicellular. 3  The cell is the basic unit of life. 4  Cells arise from pre-existing cells.