⠀The widespread division of the organic world into two "pragmatic categories" – plants and animals – goes back to the mists of time. The “father of taxonomy” C. Linnaeus “legitimized” this by dividing nature into the inorganic kingdom of “stones” (lapides) and the organic kingdoms of plants (vegetabilia) and animals animalia), “the boundary of which converges in zoophytes” . E. M. Fries  also proposed to isolate the third living kingdom – Fungi (Regnum Mycetoideum), whereas J. B. Bory de Saint-Vincent identified coelenterates and sponges as a separate kingdom Regne Psychodiaire .
⠀In the middle of the XIX century, the works of E. Haeckel [4–6] were widely known among nature scientists, in which organisms with mixed traits of plants and animals were proposed to be separated into a separate kingdom of protoctists or protists (Protoctista, Protista). Moreover, if at first Haeckel included into protists the sponges  and fungi , then in his last system  he limited this group only to unicellular and colonial organisms.
⠀At the end of the XIX century, it is planned to separate within the plant world a special group of schizophytes, i.e. bacteria and blue-green algae in the rank of the division Schizophyta . B. Nemets , basing on the nature of the cell structure of schizophytes, opposed them as
non-nuclear (Akaryonta) or primary nuclear (Prokaryonta) to all other nuclear (Karyonta) plant and animal organisms.
Such a division is accepted by most authors of the middle of the 20th century, in particular M. Chadefaud , who accepted these two large groups in the rank of kingdoms (Protocaryota with sub-kingdoms of cyanea (Cyanoschizophyta) and bacteria (Bacterioschizophyta)) and Eucaryota with sub-kingdoms of algae (Phycophyta), fungi (Mycophyta), higher plants (Cormophyta) and animals (Animalia).
⠀R. Whittaker  allocates prokaryotes to the kingdom Monera, whereas within eukaryots he distinguishes four kingdoms as protists (Protista), animals (Animalia), plants (Plantae), and fungi (Fungi).
⠀Whittaker’s work has opened a period of multikingdom Euks systems that changed kaleidoscopically during “ultrastructural revolution” but sufficiently stabilized in a course of “molecular revolution”.
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3. Bory de Saint-Vincent J.B. Psychodiaire // In: Dictionnaire classique d’Histoire naturelle, 8. Paris; 1925.
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6. Die Lebenswunder. Gemeinverständliche Studien über Biologische Phylosophie / ed. Haeckel E. Stuttgart; 1904.
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