Interaction of heterochromatic regions was studied during interphase and mitosis. The interphasic heterochromatin unites, producing 1-8 H-chromocentres. A lack of synapsis between heterochromatic regions in prophase is shown to be a result of hypotonic treatment. It is mentioned that adhesion of sister chromatids was used for heterochromatin localization. The results are discussed in connection with the supposed interaction between heterochromatin and membrane.