In young lateral shoots and seedlings of Sambucus racemosa L. the ontogenesis of elongated tannin coenocytes was investigated with particular reference to their karyology. In these tannin containers both small nuclei and giant ones are present. The DNA content in the particular nuclei was determined by the cytophotometric method after the Feulgen reaction. The ploidy of the nuclei was concluded on the basis of the DNA level. It was found that in multinuclear tannin coenocytes there are diploid nuclei as well as others with various degrees of ploidy. Thus, tannin coenocytes are mixoploidal. On the basis of karyological investigations it was attempted to elucidate the mechanism leading to the formation of polynuclear and mixoploid coenocytes.