Daily mitotic cycle in the common onion, Allium cepa.

The daily mitotic cycle of the common onion, Allium cepa, comprises 54.14±1.07% interphase, 39.07±0.99% prophase, 2.39±0.26% metaphase, 1.56±0.26% anaphase, and 2.77±0.38% telophase on the average. Interphase always has the highest frequencies followed by prophase; and anaphase always has the lowest. Interphase and prophase are more predominant with the warm temperatures of the afternoons and evenings, but the other stages appear to be favoured most by the low morning temperatures.A highly significant and negative correlation exists between interphase and pro-phase frequencies, and also between telophase and interphase frequencies; the cor-relation between metaphase and anaphase frequencies, and also between anaphase and telophase frequencies, is also highly significant but positive. On the basis of these high correlation trends, regression equations for pairs of succesive mitotic stages have been proposed as perhaps distinctive of the Allium cepa mitotic cycle.There is however no significant correlation between prophase and metaphase frequencies.