726 



ADVENTURES IN RADIOISOTOPE RESEARCH 



165 kV X-rays. A 0.5 mm copper foil and a 1 mm aluminium foil were 

 used as radiation filters. The rats were irradiated at a distance of 28 em. 

 The ^^P was injected immediately after the end of the irradiation. 



Table 2. — Formation of Nucleic Acid Molecl-xes in the Organ.s of Irradiated 



Adult Rats 



' Two rats having sarcoma were used in this experiment, the whole body being protected, except the 

 ■sarcoma with an area amounting to 5 x 3.5 cm^ with a 5 mm thicl; lead sheet. 



A comparison of the activity of 1 mgm of nucleic acid P in unirradiated 

 rats, as a percentage of the activity of 1 mgm of free phosphorus in the 

 organ or plasma, with the corresponding figures for unirradiated animals 

 (cf . Table 3) shows that the formation of nucleic acid in the organs which 

 have been studied is inhibited by irradiation. Consequently, the effect 

 of X-rays which has been observed on the sarcoma and which inhibits 

 the formation of nucleic acid, extends to the non-growing normal organs 

 •of adult animals. 



