Abstract
1) The distribution of frequencies of the chromosome number contained in the pollen grains of the hybrid plant (n=16) of A. Cepa×A. fistulosum was investigated. According to the writer's observations for a two year period, over 70 percents of all the pollen has the normal chromosome number (n=8) and ca. 20 percents, n=9. This ratio occurred annually.
2) In cases with chromosomes above the normal, the distribution of frequencies of chromosome number in this material coincides with Poisson distribution, regardless of the observed frequencies of pollen containing chromosomes less than one genome, which seems to perish for the mcst part prior to arriving at the first pollen mitosis. This hybrid plant multiplys mainly by bulbs, seed production being of rare occurrence.
3) The pollen with a SAT-chromosome derived from A. fistulosum and with that from A. Cepa amounted to about half and half in the normal metaphase plates of this hybrid plant.
