5. The following results have been obtained to date on haploid frequencies in seedling progenies from untreated and x-rayed (1500 r-units) pollen:

  N 2N
From untreated pollen 66 126,308
From x-rayed pollen 31 24,619

The haploids were identified with the aid of recessive seedling genes, stomate examination and root-tip chromosome counts.

L. F. Randolph