23 days 



33 days 



Controls 



Cortisone 



ACTH 



Cortisone 

 + ACTK 



Fig. 5. The effect of cortisone (0-25 mg./lCO g. body wt./day) and 

 ACTH (0-2 i.u. /animal/day) administered for six days on the size of 

 the adrenal cortex in young rats aged 23 and 33 days. Stained with 



Sudan Black. 



facing page 175 



