R. H. Whittaker classified living world into five kingdoms. All prokaryotes were placed in kingdom Monera. All unicellular eukaryotes like Paramecium, Chlorella and Chlamydomonas were placed together in kingdom Protista. All multicellular eukaryotes were separated on the basis of mode of nutrition, autotrophs were placed in kingdom plantae, heterotrophic fungi were placed in kingdom mycota and animals were placed in kingdom animalia.