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 IAS ee eae a See 52 | 
2 BB! Squier 4s es cengigr’ Se ee ee eg 34 
3 BB ssbletmnercntle 06603: 34 
4 oat dale th 18 
5 SOR RPE ULES 35 
6 teach ee aie es Re aoe 29.6 
7 OR ott Oh od cats 15 | 
8 Oe able dt checoctie. 8 29 | 
Averages 41.7 3b. 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, 1. 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. 
it Bihaiat. wes oars. thea 14 
2 rok Mapai e aad aN BONS bs WRN ty ae 20 
3 SE SRSA 0 RAC MERTEN EER SOS eM 2 
4 ts ey RSC eee ee 2 
5 ED is ni a ies lb 4 
6 Nae Ma ate akc o aly Nea A a att 4 
Averages 25.5 6.7 1 
