Key points are not available for this paper at this time.
This article constitutes part of McClintock's larger body of work on ring chromosomes in which she found that the chromatid breakage-fusion-bridge (BFB) cycle occurred only in the germ cells and endosperm, while the chromosome BFB continued in the sporophyte, which meant that she could selectively produce persistent variegation in plant tissues.
Barbara McClintock (Sat,) studied this question.