Colchicine stimulation of yeast growth fails to reveal mitosis

The formation of the yeast bud has generally been believed to be a partitioning of the materials between the mother cell and the bud, rather than involving a mitotic division of the nuclear material. Three investigators have presented evidence for a mitotic division, but the evidence has not been entirely convinc-ing. Colchicine delays mitotic division at the metaphase and has been helpful in the study of cell division in both animal and plant cells. A proper concentration of the drug should delay any mitotic division of yeast, change the rate of growth and per-mit the observation of division figures. Instead, colchicine stimulates yeast growth and fails to show mitosis. I The yeast used is a pure strain of Saccharomyces cerevisiae Hansen from a single cell isolated by the writer in 1928 (A. T. C. No. 4360) and was grown at 280C. in 10 ml. Williams ' original medium consisting of sugar 20 grams, (NH4)2SO4 3 grams, KH2PO4 2 grams, asparagin 1.5 grams, CaCl2 and MgSO4 each 0.25 gram aq. dest. 1000 ml. The medium was tubed, sterilized and inoculated as described by Richards (1932). Mallinckrodt's U. S. P. colchicine was used in the experiment in preference to Merck's colchicine as the latter was not chloroform free. Two check experiments with the Merck drug gave very nearly the same results so that with yeast either might have been used and without significant differences. 1 Experiments series 162 and 163 were grown at New Haven, 164 at Wood