The Effects of Radiations on Biological Systems I. Influence of High-frequency X-ray Radiation upon the Duration of the Prepupal Period of Drosophilae by Raymond Hussey, William R. Thompson, Robert Tennant, and Nancy

Some results of investigations conducted in this laboratory concerned with the influence of x-ray irradiation upon the duration of the prepupal period of Drosophila melanogaster have been reported 1,2 previously. In every instance an extension of the larval period resulted. In the case of high-frequency radiation, investigations of the course of such effects could not be extended as much as was desired, on account of the low power of sources then available. However, over the early part of the course it was definitely indicated I that the duration of the prepupal period was an increasing function of the time of irradiation under the given conditions. In the absence of more powerful sources investigations of effects of more extensive irradiation were conducted 2 with the inclusion of radiations of lower frequency in order to increase the available power. The demonstration of a maximum point of effectiveness of prolonged irradiation (in extension of the mean prepupal period, ¢) was a striking result. I t is the purpose of the present communication to give the results of similar experiments employing high-frequency radiation from a more powerful source. 3