Frequency of Translocation. In certain cultures, translocation frequency was determined by direct cytological examination of the F1 plants in every plant with segregating defective pollen. The cultures examined included the entire population given the ultraviolet treatment "X2967" and the entire population from one ear given the Xray dose "250 r" and one ear given "500 r." The results are shown below:


  Segregating Pollen Diakinesis Association
  Population Semi-
Interchange Deficiency-Association
X2967 136 21 4 2 0 3
250 r 97 14 0 0 4 2
500 r 83 20 7 3 11 6


It is noteworthy that deficiency-associations are found with Xray as well as UV treatment, but in the former they occur with a larger number of interchange-associations, while with the latter they do not.