An attempted analysis of the tetrads in the complex heterozygote species of the sub-genus Oenothera.

The statistical parameters of a pollen population of Oenothera purpurata in which the mendelian factor of pollen lethality segregates, showed that the pollen population analysed at anthesis in the Oenothera sub-genus quite faithfully conserves the segregation indicated in the tetrads. Following on this fact, the segregation "active grains, inactive grains, empty grains" was analysed in the pollen of the complex heterozygotes. The large standard deviation of the percentages of the three pollen classes and the value of the correlation between the percentages of grain classes taken two by two signify that the segregation of the three potential classes of microspore differs from one tetrad to another. By superimposing the correlation coefficient estimated between the percentage of the three grain classes of a bifactorial segregation of corn pollen on the correlation coefficient of the three classes of Oenothera pollen, it is possible to know with certainty the distribution of the potentially active, inactive and empty microspores in the tetrads. This distribution, which is different depending on whether the species is heterogamous or isogamous, allows us to confirm that the empty grains carry the recombined complexes which become lethal as a result of this recombination.