Abstract
When the cells of Drosophila embryos are dissociated and cultured in vitro, aggregation of the cells begins rapidly and movements of the cells continue for at least 5 days. Oenocytes, hypoderm, nerve, muscle, and trachea cells take up characteristic positions in the aggregates. Cells from X2 mutant embryos sort out in identically the same way as do cells from normal embryos.