ESTIMATION OF THE MITOTIC CYCLE IN LARVAL BRAIN CELLS OF THE HOUSE FLY

An attempt to estimate the mitotic cycle in brain cells of the house fly was made by injecting thymidine-methyl-H3 into third instar larvae. The G2 period plus prophase was about 1.5 hours for some of the XX and XY cells. The graph of the percentages of metaphases labelled deviated considerably from the theoretical expectation, preventing a valid estimation of the duration of G1, S, mitosis and total cell cycle. The probable causes of such deviation have been discussed.