The <<cellular theory>>, elaborated during the 19th century by researchers such as Lorenz Oken, Matthias Schleiden, Theodor Schwann and Rudolf Virchow, greatly modified the conception of life that Man had had up to then, since it asserted that the cell is the basic organic unit of all living beings and that every living being stems from a cell. Indeed, the study of the unicellular paramecium shows that a cell must be considered as a complete living form insofar as it illustrates by feeding, growing, defending and reproducing the general fate of all living creatures. Its living space, generated by its movements, is relative to its needs and therefore to its behaviour.