The nucleolus and parachromatin of the ascites tumor cell.

1. A method is described for distinguishing the ribonucleoproteins of the nucleolus and parachromatin of ascitic tumor cells of the mouse. 2. In these cells the transfer of ribonucleoprotein from the nucleus to the cytoplasm can occur in two ways. (a) At the end of prophase the nucleolus separates from the chromosomes and nucleolar fragments are released into the cytoplasm. (b) During prophase the parachromatin is aggregated to form parachromatin bodies which are discharged into the cytoplasm, where they can be detected during metaphase, anaphase, and telophase. 3. A metachromatic form of RNA is demonstrable, and may be synthesized, in close relation to the chromosomes during prophase, metaphase, and anaphase. During telophase the distribution of metachromatic RNA changes, the chromatin loses its metachromasia, and intranuclear metachromatic parachromatin becomes evident.