[Staining of the X chromatin].

A staining method suitable for the selective demonstration of X-chromation and other types of chromatins is described. On the basis of the behaviour of chromations four types of cells (in males only two) can be distinguished. From the changes of the proportion various types of cells, conclusions can be drawn concerning the alteratins of cell kinetics. These changes raise the question of the existence of a general basical biological rhythm. The duration of a cycle in this rhythm is 73 days. These cycles considerably modify the course of different diseases and the efficacy of the therapy applied. Thus the investigation of the chromatin is a useful tool for the prognosis and the therapy. The chronic myeloid leukaemia was detaily analyzed. Practical importance of the data obtained seems to be obvious.