congdon: effects of radium on living substance.: — I. 351 



very unlikely because the radiations give up their energy not only to 

 the surface of the egg, but to the internal portions as well. Abun- 

 dant analogous experiments with light on insect eggs, larvae, and 

 pupae have given accelerations or retardations of growth. 



TABLE I. 



Number of Intensity of Percentage of Average, 



the experiment. beta rays. retardation. 



1 48 52] 



2 48 16 ^ 34 



3 48 34] 



4 38 181 



5 38 35 



6 38 51 i 29.6 



7 38 15 I 



8 38.  29 J 



Averages 41.7 31.2 



Table I shows the effect upon growth inside the egg case due to 

 exposure to the one hundred milligrams of impure radium at the dis- 

 tance one centimeter (nos. 1-3) or two and a half centimeters (nos. 

 4-8). The intensities were calculated by the method already de- 

 scribed. Alpha rays were screened off by using just sufficient paper 

 to absorb them all. The beta radiations under these conditions con- 

 tained about three fourths the energy of the remaining (beta and 

 gamma) radiations. The other fourth, consisting of gamma radia- 

 tions, must have given up to the eggs, relative to its energy content, 

 much less than the beta radiations, because the former are the more 

 penetrating. The effect of either intensity of exposure was a retar- 

 dation. The average of the retardations produced by intensity 48 

 was greater than the average for the intensity 38, i. e. the retarda- 

 tion was greater with the more intense exposure. 



TABLE II. 



Number of Intensity of Percentage of Percentage of 



the experiment, beta rays. retardation. acceleration. 



1 33 14 



2 31 20 



3 25 2 



4 23 2 



5 20 4 



6 15 ^^ 4__ 



Averages 25.5 6.7 1.0 



