Pollination of Hybrid 128, Triticum compactum humboldtii, with 21 gametic chromosomes, by pollen from Aegilops cylindrica, with 14 gametic chromosomes, resulted in a plant like the 9 parent in appearance, but very sterile, producing only 9 seed, or 1 per 380 flowers. The plant is haploid and its somatic nuclei contain 21 chromosomes instead of either 42, the sporophytic number for Hybrid 128, or 35, the sporophytic number for the wheat-Aegilops cross. Injury to the flower during the artificial pollination or the presence of foreign protoplasm is suggested as cause of development of the unfertilized egg. In sporogenesis of the haploid the 21 chromosomes of the pollen-mother cells fail to pair and are distributed in the 1st division, apparently by chance, to the 2 poles. The pollen grains vary greatly in size and in number of contained nuclei. Coalescence of pollen-mother cells sometimes occurs, resulting in giant "pollen grains." Fusion of somatic nuclei in pairs and subsequent mitosis frequently takes place in ovaries and anthers. In the discussion of results a diagram illustrates a hypothetical relationship of chromosomes in wheats and in Aegilops cylindrica. The haploid Hybrid 128 is triploid in respect to the genus Triticum, and its nuclei contain 3 dissimilar sets of 7 chromosomes each, and synapsis fails on account of the absence of homologous mates. A wheat with 14 gametic chromosomes contains 2 dissimilar sets of 7 chromosomes; a wheat with 7 chromosomes, 1 set; and Aegilops cylindrica, with 14 chromosomes, 2 sets. The set in a 7-chromosome wheat is present in a 14-chromo-some wheat and also in a 21-chromosome wheat. The 2 sets in a 14-chromosome wheat are present in a 21-chromosome wheat. One set of Aegilops cylindrica is present in a 21-chromosome wheat, the other set is not and hence its 7 chromosomes fail to pair with the wheat chromosomes in the cross. Neither of the 2 sets of A. cylindrica is present in a 14-chromosome wheat and hence pairing fails completely when the 2 plants are crossed.