10 C. p. Leblond 



the only one to have a concentration above background in the 

 uterus. 



The autoradiographic detection of pure progesterone has 

 not yet yielded results. However, impure progesterone 

 containing methyl 3-keto-J*-etiocholenate showed interesting 

 autoradiographic reactions. The most precise localization 

 was observed in liver and uterus (Figs. 1 and 2). 



(3) Distribution of Deoxycorticosterone Acetate. The results 

 at 12 hours after injection were very similar to those reported 

 above. However, with this substance the urinarv loss was 

 greater than the fascal loss. The intestinal content of radio- 

 activity at 12 hours after injection was correspondingly lower 

 than with other steroids. The material in urine and faeces 

 was mainly water-soluble. The smallest concentration to be 

 found in any organ was in the adrenal. The radioactive 

 material persisted in blood until 144 hours after injection, 

 while it had vanished from other organs and tissues. The 

 loss as CO2 was 6-7 per cent within 12 hours after injection 

 in the 5 mice in the long duration experiment. At 97 hours 

 no activity could be detected in the CO2 over a 12-hour period. 



Discussion 



The most clear cut results were those obtained in relation 

 to excretory processes. Fgecal excretion played an outstand- 

 ing role, especially with cestrone and progesterone; and, since 

 the highest concentrations by far were found in the bile, there 

 was little doubt that the bile was the source of the material 

 excreted in the faeces through the intestine (as demonstrated 

 by Albert et al. for the iodo-oestradiols). The fact that the 

 faecal material, as well as the urinary material, was mainly 

 insoluble in fat solvents even after hvdrolvsis indicated that 

 the metabolism of oestrone, progesterone and deoxycorticos- 

 terone in mice differed from what was known to occur in man. 

 This was indeed found to be the case in the work reported by 

 Gallagher in this volume. The excretion as COg was appre- 

 ciable, but smaller than that by faecal and urinary routes. 

 The fact that we obtained smaller CO2 excretion and greater 



