1. Meiosis in autotetraploid Secale cereale is characterized by multivalent associations, inversion or duplication bridges, univalent bridges, univalent laggards and nonlaggards, irregular anaphase distributions, and chromosome loss. 2. The degree of anaphase irregularity is so low as to indicate that the spindle mechanism is as precise in the autotetraploid as in the diploid. 3. Unequal anaphases are produced by nonlagging univalents and coincidences in the divisions of trivalents. 4. Chromosome loss seems to interfere little with mitosis until the reduction leaves little more than the haploid number. Hypoploid cells were capable of division, the extreme instance being the division of a cell deficient for three whole chromosomes. The loss occurs frequently, usually within five or six cell generations before the first meiotic division, and may be followed by additional loss within the islands of deficient cells.