Coincidence and Interference in Drosophila melanogaster

Abstract

The calculation of coincidence from data on incompletely marked chromosomes leads to conclusions on the X and II chromosomes of D. melanogaster which are inconsistent with those arrived at from a study of translocations, inversions, etc. An alternate method of calculating interference relations is presented, giving more directly their mutual influence of crossing-over in 2 regions on each other when no crossing-over is occurring in other regions. In computing interference, all singles, and multiples involving any regions except those being considered, are excluded. When computed in this way from data having few undetected double cross-overs, it is found that for the X and II there is no modal length of intemode (loop), and for II the independence of the left and right arm is also established.