Abstract
(1) The problem of coincidence in crossing-over presents a variety of cases for consideration. In general, coincidence between adjacent regions is lower than I.O. But it often exceeds I.O in the middle region of the V-shaped chromosome, in the translocated chromosomes, or in the ring-formed chromosomes. These facts may be easily accounted for by the assumption of incomplete synapsis or asynapsis.
(2) In the case where non-adjacent regions are codsidered, the gross-coincidence method is more adequate than the usual partial-coincidence method. Thus it has been found that interference is complete to a certain point from the original break, but from that point on, the effect suddenly disappears.
(3) From the study of the various cases, the conclusions reached in my previous papers (1932, 1933) are in the present paper somewhat revised.
