4. Further study with the chromosome 5 fragment (see maize letter of November 24, 1934) has placed the following genes in the long arm of chromosome 5: v₂, ys, pr, v₁₂, v₃, and bt. The loci of a₂ and bm₁ are in the short arm of chromosome 5. The fragment chromosome, which is composed of the short arm of chromosome 5 and has a terminal insertion region, occasionally passes through the pollen. In the progeny of a selfed fragment plant there occurred an individual with the normal complement of 20 chromosomes plus two fragment chromosomes. In genetic constitution and appearance this 22 chromosome plant was identical with the secondary trisome found several years ago in which the single supernumerary chromosome was composed of two short arms of chromosome 5. Plants having a single fragment chromosome were studied at pachytene. As reported before, the fragment pairs with the two normal chromosomes 5 in approximately half the cells. It was occasionally observed in those cells where the fragment was unpaired that the terminal insertion region presented the appearance of being split. This observation may have some theoretical importance since some of the prevalent theories of meiosis assume that the reason the spindle fiber region undergoes a reductional division in the first meiotic anaphase is that the division of the insertion region is delayed to a late prophase stage while the split of the chromosome thread occurs in the early prophase stages.