Chromosome disjunction.

In discussing with many others the problem of getting lower sterility from large rings, the possibilities of genic control were suggested. On this basis, a planned search for factors affecting chromosome behavior at meiosis, such as changed chiasma frequency or position, may be needed. Those studying inbred lines for knob number night be on the look‑out for such effects at diakinesis and metaphase. Such stocks would be of interest for other problems also.

Since such factors are likely to be recessives, it will be necessary to study selfed lines from X‑ray treatment rather than the immediate plants obtained from the use of X‑rayed pollen. I wish to acknowledge the assistance of H. A. McKennan, F. H. White, and K. Hanson.

C. R. Burnham