SYMPOSIUM OX RADIOACrmTY. 81 



destroyed. Experiments on various eggs, embnos, and larvae 

 have shown, as would be expected, in these embr^'onic tissues, a 

 high degree of susceptibilit}-. Growth is retarded, monstrosities 

 develop, and, from prolonged exposure, death occurs. 



In lower forms of plants and seeds the results of experiments 

 may be summarized briefly as, first stimulation of growth, and 

 under stronger application, retardation or complete inhibition of 

 growth. 



This consideration has been directed to the effects of radium 

 rays. As to the emanations, it may be stated briefly that experi- 

 ments with the emanations upon young mice, upon bacteria, and 

 upon protozoa show results quite like those from exposure to 

 the rays. 



There is apparently no difference in kind in the effects upon 

 tissues between the different radium rays. Alpha rays have so Uttle 

 penetration that their effect is expended entirely upon the most 

 superficial tissues, but when they are screened out the only dif- 

 ference in the reaction is one of intensity and depth. Exner, in 

 a repeated experiment, by deflecting the Beta rays by an electro- 

 magnet directed them upon a white mouse while the Gamma raye 

 fell upon another mouse equidistant from the radium. Fifteen 

 days after exposure, which had been for 18 2 3 hours, a similar 

 ulceration appeared on the tails — the exposed areas — in both 

 mice. All three forms, of radiiun rays then, are physiologically 

 active. This fact might fairly be inferred from their actinic 

 properties. For the biological effects of ail forms of radiant en- 

 tTgy, there seems ever\- reason to believe, are a manifestation of 

 the same actinic effects that we have long been familiar with in 

 crtain inorganic substances. Indeed beginning with the red rays 

 of light at one end of the scale and ending with the hardest X- 

 rays and Gamma at the other, we find physiological effects dif- 

 fering chiefly in degree and corresponding in intensity with the 

 actinic strength of the respective rays. 



What the bio-chemical processes are that are set going by rad- 

 ium, or by the more familiar forms of actinic energ>-, we are in 

 no position to say. From experiments with radium upon eggs 

 Schwartz proposed that all of the effects of radium upon tissues 

 were due to decomposition of lecithin. Hussakof suggests from 

 experiments of Willcock. Zuelzer, and Komicke that ox)-gen in 

 some not understod way seems to play a part in the process. 

 There is every reason to believe that the process is not expUcable 



