1. It was found from a cytological observation that the giant cells formed in a completely sterile rice plant induced by X-rays are syncytes and not coenocytes.
2. There was not observed any morphological difference that distingushed the syncyte-forming and normal plants.
3. Twenty-four chromosomes were counted in the somatic cells of the sterile plant.
4. The cell fusion to form syncytes was found to have started already at the early stage of meiosis.
5. Number of nuclei per PMC varied from 0 to 21.
6. Chromosome configulations per nucleus varied from 8_II+8_I to 69_II+3_I.
7. The muximum chromosome number counted was about 220.
8. No data on the genetic behavior of syncyte formation were obtained because of the complete sterility of this plant.
9. There was a great variation in the size of pollen grains.