EFFECTS OF LOW X-RAY DOSES 23 



Generally speaking, the number of cells is increased between 28th and 98th 

 days in favour of the rats irradiated with 1 r. 



After 0-1 r, the numbers of cells per mg of marrow are higher between 28 

 and 56 days but the differences are not significant except slightly after 42 days. 



Erythropoietic activity 



The red-cell incorporation of ^^Fe into the peripheral blood of the rats 

 pre-irradiated with 1 r or 0-1 r and of the controls with their statistical 

 significance are recorded in Tables V and VI. 



^o^ 



Table V. ^^Fe activity in red cells (counts/min per ml for 10^ cells) 



Time after „. .„ 



,. ,. 1 n i. 1 bigmticance 



irradiation Ir Controls °, , ,, 



(days) (*-*^"*) 



Table VI. ^^Fe activity in red cells (counts/min per ml for 10^ cells) 



Time after „. 



irradiation 0-1 r Controls , , ' 



(days) (*-*^^*) 



The incorporation of ^^Fe in the red cells of rats pre-irradiated with 1 r 

 is higher than in the controls; the results are highly significant after 28, 42 

 and 56 days, slightly after 84 days. For the 0-1 r pre-irradiated rats, the results 

 are higher but the enhancement is not so large as after 1 r. Anyway, the 

 difference of ^^Fe incorporation between the pre-irradiated animals and the 

 controls is significant in favour of the pre-irradiated rats after 28 and 42 days 

 and slightly significant after 14 and 56 days. 



Reticulocyte counts 



The results are collected in Tables VII and VIII. After 1 r, the reticulo- 

 cytes are significantly increased by the 14th day, increased by the 28th day 



