The Chromosomes in the Nurse-cells of Drosophila melanogaster

1. Chromosome changes observed in the nurse-cells of Drosophila ovary do not indicate that endomitosis or simple chromosome reduplication occurs in these cells. The increase in volume which their nuclei exhibit is probably due to an increase in length rather than in number of chromosomes. 2. It is evident that up to a certain stage of development of the nurse-cells their chromosomes behave quite like those in meiotic cells: the homologues synapsize and relationally coil about each other, and then each split into two chromatids. It is suspected that chiasma-formation may also occur. Nothing like an actual meiotic division I, however, has been observed. After the homologues have freed from each other, reticulation of the nucleus follows sooner or later. An increase in nucleolar mass accompanies all these changes.