Abstract
Bud-forming capacity of XD-6, a strain of tobacco callus subcultured for 8 years, was tested at various periods after transferring to new culture medium. It was found that bud-forming capacity increased with the age of such a single culture. No bud-formation was seen in the earlier period but many buds were formed in the later period. Nuclear features of the callus were also observed at various periods. The cells exhibited a wide range of size and shape. The nuclei were exceptionally large and there were sometimes more than two per cell in the earlier period. In the later period, however, the size and shape of cells and nuclei were relatively uniform. Possible relevance of the nuclear features to the bud-forming capacity is discussed.
