KANEMATSU SUGIURA AND GIOACCHINO FAILLA 433 



tion on the longevity of white mice. The number of animals used was 

 too small to apply statistical methods, and some of the mice are still 

 living. It is interesting to note, however, that even those mice which 

 showed severe local and constitutional effects from the radiation 

 apparently did not have their lives shortened appreciably. Some were 

 a little undersized but otherwise apparently normal on the 618th day. 

 Table III shows the number of mice still living at two different periods 

 in the course of the experiments. 



DISCUSSION AND SUMMARY. 



It has been estimated^^ that 92 per cent of the total radiation emitted 

 by radium in equilibrium with its subsequent products is given off in 

 the form of a-rays. This, however, cannot be utilized when the 

 source is enclosed in an ordinary container, because the a-rays are 

 absorbed completely by even a small thickness of glass. About 3.2 

 per cent of the total radiation is emitted in the form of /3-rays, and 

 4.8 per cent as gamma radiation. The effects produced on the 

 radiated mice of these experiments were due mainly to the j8-rays, 

 which are easily absorbed by tissue. The 7-rays, being only 

 shghtly absorbed by organic matter, probably contributed very little 

 to the observed effects. 



It is interesting to correlate the different effects produced by the 

 same dose of radiation. The mice which received a dose of 1.9 milli- 

 curie hours showed no local effects on the skin or hair. Neither fe- 

 males nor males were sterilized, and the time at which they opened 

 their eyes or reached sexual maturity was not affected, as far as we 

 could tell. The only difference noted between the radiated animals 

 and the controls was in the body weight. This dose accelerated the 

 growth of the young mice, that is, while initially of the same weight, 

 soon after irradiation they became distinctly bigger than the con- 

 trols, but finally the animals of each group had substantially the same 

 average weight. That this variation in body weight should be acciden- 

 tal is unlikely, since it was observed also in the animals treated by a 

 slightly larger dose (2.4 millicurie hours). The number of animals 



'^ Rutherford, E. Radioactive subtances, and their radiations, Cambridge, 

 1913, 581. 



