THE QUANTITATIVE DETERMINATION OF MITOTIC ELONGATION

¹ From the Department of Zoölogy, University of Pennsylvania, and Marine Biological Laboratory, Woods Hole

For the experimental temperatures (22.2° C.–26.0° C.), curves have been plotted to show the course of mitotic elongation in the Arbacia egg at first cleavage. For eggs possessing fertilization membranes, the elongation is 11.5 per cent (i.e., an egg 74.0 µ in diameter elongates to 82.5 µ). When eggs are divested of their fertilization membranes, the elongation is 39.4 per cent—or, an egg 74.0 µ in diameter elongates to 103.2 µ. The data obtained are being used as a basis for further experimentation.