An equation for calcg. the mol. wt. distribution of a living polymer in a periodically-stirred tank reactor was derived. Polymer inhomogeneity was detd. under various reaction conditions. The use of a d-functional type of control of the vol. flow rate of the product stream theor. enables the prodn. of polymers with nonuniformity 0-.... A multimodel distribution function was a special feature of the periodic reactor control.