Chromosomes in Osmunda

The reticulum in the young nucleus arises fron the chromosomes of the previous division by vacuolation. It consists chiefly of chromatin material. 2. The chromatin network during the resting stage shows no indication of a pairing of knots or strands. 3. Individuality of the chromosomes is retained in the vacuolate and reticulate form during the resting stage, although the limits of individual chromosomes become hard to trace. 4. The pairing of chromatin material, perhaps of maternal and paternal derivation, appears only at the early prophase of heterotypic mitosis. The pairs may come into the closest association during synapsis, but the duality is maintained. As a consequence no actual fusion occurs. 5. There is no splitting of chromosomes in the heterotypic mitosis; each bivalent chromosome is formed by the association of two independent chromosomes. The separation of the two gives an appearance of longitudinal division.