The eggs of Philosamia were exposed to 800r X-rays for 2 minutes. It was shown that the 800r X-rays exposure had a definite effect on the development and other aspects of Philosamia.1. The percentage of hatching in the treated eggs is obviouslly lower than that of the controls.2. The length of the larval period in the treated eggs is universally postponed or elongated.3. The death rates of the treated hybrids (the F1 eggs of Philosamia cynthia X white yellow and spotted yellow X white yellow) is universally...