Peculiarities of Oenothera breeding behavior and cytology, and Cleland''s hypothesis which attempts to correlate these peculiarities, are discussed. There are 2 basic assumptions in Cleland''s hypothesis: (a) that homologous chromosomes are adjacent to each other in the chains or rings, and (b) that chromosomes of maternal and paternal origin alternate with each other in a definitely fixed order. The evidence is considered convincing for the 1st, but not for the 2nd, of these assumptions. An alternative hypothesis is advanced, namely, that the arrangement in the chains or rings of the pairs of homologous chromosomes is indeterminate, that is, the connections between non-homologous chromosomes to form a continuous spireme occur independently of their maternal or paternal source. Such an arrangement provides for a chance assortment at each pole of chromosomes of maternal and paternal origin, just as in plants with separate chromosome pairs. Also, there would be as many independent linkage groups as there are haploid chromosomes, and the grouping of the chromosomes in chains or rings would seem to have no very fundamental genetical significance.