Chromosome Degeneration in Relation to Growth and Hybrid Vigor

mitotic figures and newly formed cell walls are frequent in these large cells. The author2 has recently shown that relatively large, vacuolate cells like those here discussed commonly divide in meristematic regions. For this material, at least, there is no relation between the volume of a cell and the rate at which it divides. In larger cells, the amount and rate of cell expansion, from the time when a new daughter cell is formed until this cell is ready to divide again, is evidently greater than in smaller cells. Whether this increase is in protoplasm or only in the size of the vacuole is not known. Rate of cell division seems to be determined by some factor independent of cell size and operative throughout the entire organ.