English: Kandler's Pre-cell theory - Scheme of cellularization (Kandler 1994, p. 155). Scenario of the origin and early diversification of life and the formation of precursor cells of each of the three domains by successive cellularisation processes. A, B, C: founder groups of the three domains.

Important evolutionary improvements are indicated by numbers: (1) Reductive formation of organic compounds from CO or CO2 by Me-sulfur coordinative chemistry; (2) tapping of various redox energy sources and formation of primitive enzymes and templates; (3) elements of a transcription and translation apparatus and loose associations; (4) formation of pre-cells; (5) stabilised circular or linear genomes; (6) cytoplasmic membranes; (7) rigid murein cell walls; (8) various non-murein rigid cell walls; (9) glycoproteinaceous cell envelope or glycokalyx; (10) cytoskeleton; (11) complex chromosomes and nuclear membrane; (12) cell organelles via endosymbiosis (Kandler 1998, p.22).

References: Otto Kandler (1994). The early diversification of life. In: Early Life on Earth. Nobel Symposium 84 (S. Bengtson, ed.) Columbia U.P., New York, pp. 152-160

For more detailed informationː Otto Kandler (1998). The early diversification of life and the origin of the three domains: A proposal. In: Thermophiles: The keys to molecular evolution and the origin of life? (J.Wiegel, M.W.W. Adams, eds.) Taylor and Francis Ltd., London, pp. 19–31