[Variability in chromosomes number during plant ontogenesis].

The experiments on chromosome variability of cells in the ontogenesis of higher plants are reviewed. The polyploidization of somatic cells during the ontogenesis is shown to be the natural phenomenon for most plant tissues and it is correlated with the intensification of cellular metabolism. The functional and chromosome variability of somatic cells is supposed to depend mostly on the hormonal regulation. The possible role of the phytochrome system in this process is discussed.