The effect of radium on mitosis in vitro

Abstract

The authors record the effect of radium irradiation in stopping mitosis in the choroid of the chick cultivated in vitro. The amounts of radium element used were 2 tubes of 50 mgm. each, filtered with 0.5 mm. of Pt. The distances from the cultures were varied. In some experiments an ordinary biological incubator was used, and the cells subsequently observed under the microscope in a specially constructed wooden incubator. Other observations were made during the process of irradiation, in a special Pb incubator. Experiments were adequately controlled by sister non-irradiated cultures. The authors show that, at the commencement of irradiation, the cells not only complete mitoses which have begun, but also commence and go through mitosis apparently normally. After a time, however, which is greater with less intense irradiation, mitosis ceases to appear. The decrease in number of cells in mitosis is sudden. If after several hours'' irradiation the radium is removed, mitosis reappears after a time.