SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 92, NO. 3, PL. 2 



b 



c 



a 

 b 

 c 



TIME AFTER IRRADIATION 



12 DAYS 



23 DAYS 



38 DAYS 



59 DAYS 



2652 A 2894 A 



Gradual appearance of Radiotoxic regions in Puate 5 of Chloreul.a 

 VULGARIS After Exposure of 600 Seconds to Ultraviolet Rays. 



No radiotoxic el'fect was noted for exijosures of lOo seconds and i6 seconds. 



