Abstract
1. Feulgen-positive bodies were found in the cytoplasm through all the stages of microsporogenesis in Allium odorum.
2. The extranuclear bodies (“e” bodies) mentioned above are round or ring-shaped, and their number within a single cell varies from one to seven. The average diameter is about 3.9μ. The average frequency of occurrence of cells having an “e” body or bodies in all stages, discounting the stages of one- and two-nucleated pollen grains, is 6.7%.
3. During the development of pollen grains the “e” bodies exist as the centre of micropollen grains isolated from the mother cell.
4. The occurrence of the “e” bodies is independent of meiotic irregularities.
5. The frequency and kinds of chromosome aberrations in this species were observed. In the anthers which contain synchronized and non-synchronized pollen mother cells of the division phases, the frequency of occurrence of the cells accompanied by chromosome breakage is an average of 5.3% and 1.1% respectively, while that of other irregularities (mainly, lagging chromosome) is an average of 0.7% and 7.9% respectively. From these results, it is concluded that chromosome breakage and non-pairing seem to result respectively from separate mechanisms, independent of each other.
In conclusion the author wishes to express his sincere thanks to Professor T. Shimamura for his kind criticism and valuable advice. Thanks also due to Dr. M. Kumazawa and Dr. I. Harada for their helpful suggestion.
