428 EFFECTS OF RADroM RADIATIONS ON WHITE MICE 



The weight of the radiated mice remained distinctly larger than that 

 of the controls until about the 27th week. After this time the average 

 weight of the two groups was substantially the same. A dose of 11.5 

 millicurie hours had practically no effect on the body weight of the 

 mice, A dose of 21.9 millicurie hours, however, had a marked in- 

 fluence on the growth of the radiated mice. They remained distinctly 

 smaller than the controls for several months, but finally (in the 

 45th week) their average weight was the same as that of the control 

 group. The mice which received a dose of 31.6 millicurie hours were 

 affected very seriously by the radiation. Their growth was greatly 

 retarded and they died on the 12th day. The effect of a dose of 36.5 

 millicurie hours was even more marked, and the mice died on the 

 9th day. 



The results just described may be summarized as follows: (a) Suf- 

 ficiently small doses of radiation accelerate the growth of suckling 

 white mice, (b) A larger dose of the proper value will have no in- 

 fluence on the body growth of mice, (c) A still larger dose, up to a 

 certain Umit, will retard growth, but the animals will eventually attain 

 normal size, (d) Still larger doses cause premature death. Similar 

 results have been obtained before in experiments on seeds and plants,^-® 

 also on lower forms of animal life exposed to x-rays.'-^ From these it 

 is commonly assumed that the action of radiation on the living cell fol- 

 lows the same general law^ which governs the action of all anes- 

 thetics, as well as chemical, mechanical, and electrical stimulants; 

 that is, if some form of energy is gradually brought to bear on the 

 cells, at first they may be stimulated to greater activity, then their 

 normal function may be arrested, and finally they may be destroyed. 



As a result of the mode of application of the radium emanation 

 adopted in these experiments, the upper part of the body of the animals 

 was exposed to an intense radiation. The lower part received much 

 less radiation, not only because it was farther away from the source, 

 but also because the overlying layers of tissue absorbed most of the 



^ Gager, C. S., Memoirs, New York Botanical Gardens, 1908, iv. 

 ^Molisch, H. C., Sitzungsh. k. Akad. Wissensch. Mafh-naturiv., Wien, 1912, 

 cxxi, 121. 



' Davey, W. P., J. Exp. Zool., 1917, xxii, 573. 



^ X-ray Studies, General Electric Company, Schenectady, 1919, 255, 267. 



3 Christen, Th., Strahlentherapie, 1919; Ix, 590. 



