Kappa particles are self replicating cytoplasmic bodies containing DNA. Sonnebom found that there are two strains of Paramecium, ie, killer and sensitive. Killer strain produces a toxic substance called paramecin that kills the other type. The production of paramecin in killer type is controlled by certain cytoplasmic particles known as Kappa particles. The sensitive strains lack these particles. It is an example of cytoplasmic inheritance. In this type of inheritance, most of the phenotypic characters are controlled by genes present in the chromosome but some characters are expressed by factors in the cytoplasm.