424 



EFFECTS OF RADIUM RADIATIONS ON WHITE MICE 



by Jackson^ for albino rats was used to determine the sex of the new 

 born mice. Any underdeveloped animals were discarded, but other- 

 wise the litter was divided into the two groups at random. In this 

 way individual inequalities would be divided fairly evenly between 

 the two groups. It was found, in fact, that the average weight of the 

 mice of one group from day to day was very nearly the same as for 

 the other group, when neither was treated with radium. 



Fig. 1. 



The apparatus of Fig. 1 was used to irradiate the mice, one at a 

 time. The new born animal was placed in a cavity slightly larger than 

 itself and was covered with a very thin sheet of mica. In this manner 

 the mouse remained in a fixed position during the treatment, with its 

 back touching the mica. A capillary glass tube 10 to 14 mm. in 

 length, and about 0.5 mm. in external diameter, containing radium 

 emanation, was placed on another sheet of mica which was rigidly 

 supported at a distance of 2 cm. from the animal. The holder was 



"Jackson, C. M., Biol. Bull., 1912, xxiii, 171. 



