Centrifugation of celt suspensions containing two or several cell types at forces up to 2 million g results in several basic events in succession: 1. Intracellular stratification. 2. Extrusion of the most dense cell parts (nuclei or cytoplasmic components) and their penetration into an adjacent cell in the compact sediment. Such introduction of protoplasmic elements from one cell into another is considered as centrifugal hybridization and fusion of cells. It differs from other methods of cell hybridization by its selectivity for cell components. 3. Further intermingling and mixing of ceils into a fused protoplasmic mass. 4. With continuing increase of centrifugal force fractions of subeellular components are formed from the protoplasmic maSS. These components are presumably viable since eells are not exposed to chemical treatment. Morphological demonstration of hybridization is hased on centrifuging microscopy and on labeling donor cells or recipient cells by staining or fluorescence. Genetic evidence can be provided by cultivation of hybrid cells in vitro and their cloning in vivo.