The clonal study of L cell culture has shown that the clone-forming cells are heterogeneous both in form and in the activities of enzymes (succinate dehydrogenase, lactate dehydrogenase, NAD- and NADP-diaphorase) which were determined by histochemical methods. The morphological heterogeneity is characteristic for clones with not less than 10 cells manifesting itself earlier and heterogeneity as to the activity of the studied enzymes--later, in clones with more than 15-20 cells.