Some physical parameters controlling cell size during the evolution of the procaryons.

Possible factors controlling cell size during the evolution of unicellular organisms have been examined. It has been shown that considerations of osmotic and membrane pressure eqilibria will predict minimal cell sizes which are in good agreement with those found in present day microorganisms. It has also been shown that the possibility of random proton 'noise' would not be a limiting factor for even the smallest organisms or structures. Maximum cell size would be governed by the requirements of diffusion and transport within the cell.