A number of monohybrid bird crosses have bee performed with Paramecia and the result indicates typical " Medellian Inheritance", occurs in these protozoans. Artificial induction of autonomy and cytogamy has been a useful tool in these studies by supplying genetically "Homozygous" individuals for use in the test crosses and in detecting genes present in the progeny of such crosses. Autonomy allows the contrasting characteristics of a heterozygote to segregates in a one to one ratio in the progeny of Paramecia. No segregation occurs of a homozygote after autonomy.

Some Paramecia have DNA containing particles in their cytoplasm, which produce a substance capable of killing other Paramecia that lack the particles. The particles have been named as "Kappa Particles". The Paramecia-containing Kappa is names as "Killers" because they secrete poison; called " Paramecin" that kills Paramecia of the same species-lacking kappa.

Later studies have shown that Kappa is a DNA containing hereditary complex present in he cytoplasm hence are renamed as, cytoplasm genes or plasmid. A plasmid is a double stranded, circular, extra chromosomal, DNA molecule. The plasmid is autonomus in its duplication and inheritance of gene present on it.