It was proposed by a German Zoologist Ernst Haeckel (1886). This system of classification was based upon the morphology, tissue system, and nutrition pattern and functioning of the different parts of the body of the living organisms.
He divided the living world into three kingdoms such as Protista, Animalia and Plantae. All one-celled organisms were kept in the kingdom protista. It included fungi, protozoan’s, algae and bacteria.
1) Recognition of the importance of the micro-organisms in the living world.
2) More characters were taken into consideration to classify the living beings. Demerits
1) Nucleated and anucleated organisms kept together in protists.
2) Heterotrophic bacteria and fungi placed along with autotrophic algae.