Abstract
1. During microsporogenesis there is a differentiation of the cytoplasm into a densely granular central region and an outer vacuolate zone which persists until the completion of the homoeotypic divisions.
2. The heterotypic nucleus and the homoeotypic nuclei are located toward the periphery of the cell and are almost completely imbedded in the dense cytoplasm.
3. Most of the spindle fibers are cytoplasmic in origin and are formed from the less dense outer cytoplasm.
4. The spindles of both divisions are curved about the periphery of the cell and the chromosomes are irregularly distributed over the spindle. There is no equatorial-plate stage.
5. The chromosomes disjoin independently in both reduction divisions.
6. Both divisions usually result in a normal distribution of chromosomes.
7. The possible significance of these irregularities is discussed.
The author wishes to acknowledge his sincere appreciation to Dr. C. E. Allen who suggested a cytological study of this genus, and to Dr. W. R. Taylor for his suggestions and criticisms during the preparation of the manuscript.
