Beschreibung:
Starting with oviposition, the entire embryonic development, following the early determinating dipteran type, has been recorded by 27 film takes. The transparent eggs permit to observe the migration of the female and the male pronucleus and their fusion. During 4 intravitelline mitotic waves the somatic nuclei, naturally marked by pigmented halos, get distributed over the egg plasmodium. At the posterior pole one (generative) nucleus enters the pole plasm, and the pole cell is tied off. The migration of the cleavage nuclei is caused by plasm flows as well as by the activity of the "migration cytasters", special nuclear organelles derived from the mitotic apparatus. The structural particulars and the function of the cytaster are explained in electron optical and interference contrast pictures respectively. After 8 superficial cleavage divisions the stage of cellular blastoderm has been attained. Formation, elongation, and segmentation of the germ band as well as the blastokinetic movements are of the long germ egg type. Having shortened and the serosa being removed, the embryo closes dorsally, and the larva is ready to hatch 3,5 days after oviposition