Countercurrent distribution (CCD) and Martin-Synge distribution (MSD) were compared on the basis of the theory previously presented in this series. The comparison included the numbers of partition units required to obtain the same resolution degree of two compounds as well as the elution volumes and the widths of the elution curves. The ratio of the numbers of partition units, 4, was found to be proportional to cuk, where (Y is the phase ratio and ki is the partition coefficient of the more rapidly moving component. The limit of $J when p + 1 was found equal to ok1 + 1. Accordingly, in the case CWG, = 0, the methods possess approximately the same separation power, and in case & = 1, about double the number of partition units is required in MSD as compared to CCD. In the case that c&cc, = 1 and tr/~,sn = 0, the situation becomes roughly inversal. The ratio of the elution volumes, x, in the two methods was found to be equal to + in the case that the stationary phase volumes (v,) are equal and that the q = ll(ak + 1) values are equal in the methods.' On the same conditions, the ratio of the standard deviations of the elution curves, 4, was found to be equal to 4+/q', and the limit of J, when p+ 1 equal to l/ql. If, in addition, the condition cuk, = 0 is satisfied, J, = 1. A practical comparison of the methods was also included, wherein attention was focused upon the real separation powers, the reproducibilities, the suitabilities for analytical or preparative purposes, the suitabilities for nonideal situations, the possibilities for automation, and the main structural features of some most important CCD and MSD apparatuses. 405