RADIANT ENERGY 409 



are typical degeneration effects likely to occur in any dying cell. 

 Williams finds similar effects with both X rays and gamma rays. 

 While pronounced changes usually occur, Weber finds great 

 resistance; for example, there is no change in the viscosity of 

 the protoplasm of Spirogyra and of Phaseolus seedlings with 

 treatment — which merely goes to show that protoplasm is not 

 everywhere the same. 



The effect of X rays on developing eggs may appear some 

 time after treatment, a phenomenon not uncommon in medical 

 radiotherapy, where the secondary effects of radiation are often 

 the more important. Vinternberger exposed one of the blasto- 

 meres of the frog embryo in the two-cell stage, protecting the 

 other by a lead screen. The embryo developed normally until 

 gastrulation, when the irradiated half ceased growth while 

 the other half continued. Packard has shown that irradiated 

 Drosophila larvae may continue to grow until the time of pupa- 

 tion and then first show the effects of irradiation. Species and 

 individuals of the same species vary in their sensitivity to 

 irradiation. Nereis eggs are more resistant than sea-urchin 

 eggs. The same organism is not equally resistant at different 

 periods in its fife; thus, Manor has shown that the eggs of 

 Drosophila are killed by small doses of X rays, the larvae require 

 more, the pupae still more, and the adults succumb only after 

 very large doses. Different tissues of the same organism are 

 unequally affected by both X rays and radium emanations. 

 L. Loeb states that generative organs (ovaries and testicles) are 

 most sensitive to irradiation. Lymphocytes are also destroyed 

 by very small doses of X rays. 



Disturbing the winter's rest of plants has long been of interest 

 to the botanist. Must the plant rest a definite or minimum 

 length of time before it can blossom forth again? Is the "sleep" 

 a very sound one, or can it be disturbed easily? These questions 

 Weber has attempted to answer through the use of X rays. His 

 work had its origin in some experiments by Hans Molisch, which 

 showed that radium emanations would end the resting period of 

 winter buds and bring them into leaf. As the alpha rays were 

 screened out by glass, the beta or gamma rays were probably 

 responsible. Weber continued the work, using X rays, and found 

 that they caused resting buds of Syringa to open prematurely. A 

 too heavy dose caused the growing buds later to fall. 



