[Different behaviour of paternal and maternal genomes during embryogenesis in the fern, Marsilea (author's transl)].

The DNA of gametes of the water fern, Marsilea vestita, has been radioactively labelled during gemetogenesis. The distribution of the originally present paternal and maternal genomes could thus be followed during the development of the embryo. It has been found that the maternal chromatin is uniformly distributed among the daughter cells of the several successive cell generations. However, the paternal chromatin divides equally only during the first three embryonic divisions. From this stage on, the partition varies according to the different areas of the embryo. Only the organogenic cells retain a high degree of radioactivity. This pattern of inheritance concerns chiefly the apical cells of shoots and roots. This peculiar behaviour of the paternal genome can be explained in different ways. At present, a non-random distribution of paternal chromatids, i. e. a selective segregation of old and new strands of DNA to opposite poles of embryonic mitoses, appears most likely.