< 



O 



Z 



o 



10 20 30 40 



DAYS AFTER IRRADIATION 



50 



Figure 30.- 



■Percentage of control specific activity of iron 59 in the blood, liver, spleen, and kidney of irradiated pin- 

 fish at different times after irradiation. 



to varying degrees {fig. 30). In the kidney of 

 fish injected 1 day after irradiation the spe- 

 cific activity was only 25 percent of that in 

 the controls and was also lower than the spe- 

 cific activity of the blood. The specific activity 

 increased progressively to the Z2d day, when 

 it reached the level of the control and then 

 decreased for the rest of the experiment. The 

 increase in specific activity in the kidney coin- 

 cides with the decrease in specific activity in 



the blood. From the 22d day until the end of 

 the experiment the specific activity of the kid- 

 ney decreased as that of the blood increased, 

 indicating erythropoietic activity. The spleen 

 had a lower specific activity than the blood 

 through the 8th day, then followed the changes 

 of the blood closely except for small fluctu- 

 ations. Previous investigations with iron 59 

 in pinfish have demonstrated that the spleen 

 may have some erythropoietic activity. The 



56 



