Study of spontaneous oogonial crossing over in interspecific Drosophila hybrids (Russian)

Spontaneous oogonial crossing over was studied by means of combined cytologic and genetic method in F₁ Drosophila virilis x D. texana females (I series) and D. virilis females carrying D. texana fifth chromosome in heterozygous condition (II series). The main criterion utilized to distinguish the oogonial crossovers from the meiotic ones is the identity of cytologic positions of genetic exchange in crossovers constituting a cluster. 5 Clusters of crossovers with identical positions of exchange were found in the first series of the experiment. In the 2nd series of experiments, the author failed to find a single cluster resulting from oogonial crossovers.