The development of microscopy revealed important distinctions between those organisms whose cells do not have a distinct nucleus prokaryotes and organisms whose cells do have a distinct nucleus eukaryotes. In 1937 Edouard Chatton introduced the terms prokaryote and eukaryote to differentiate these organisms. In 1938, Herbert F. Copeland proposed a four kingdom classification by creating the novel Kingdom Monera of prokaryotic organisms as a revised phylum Monera of the Protista, it included organisms now classified as Bacteria and Archaea. Ernst Haeckel, in his 1904 book The Wonders of Life, had placed the blue-green algae or Phyco chromacea in Monera this would gradually gain acceptance, and the blue green algae would become classified as bacteria in the phylum Cyanobacteria.In the 1960s, Roger Stanier and CB van Niel promoted and popularized Edouard Chatton's earlier work, particularly in their paper of 1962, "The Concept of a Bacterium"; this created, for the first time, a rank above kingdom a super kingdom or empire with the two empire system of prokaryotes and eukaryotes. The two empire system would later be expanded to the three-domain system of Archaea, Bacteria, and Eukaryota