Oparin’s central thesis was that the first organisms to emerge in the anaerobic environment of the primitive Earth must have been heterotrophic bacteria. He proposed that life had been preceded by a lengthy period of abiotic syntheses and accumulation of organic compounds that had led to the accumulation he called the primordial soup. Reprinted and translated in J. D. Bernal, The Origin of Life, London: Weidenfeld and Nicolson, 1967. Also translated by NASA as The origin and development of life (NASA TTF-488) Washington, D.C., 1968. See Lascano, "Historical development of origins research", Cold Spring Harb Perspect Biol. 2010 Nov; 2(11). doi: 10.1101/cshperspect.a002089 .