752 



ADVEXTURES IN RADIOISOTOPE RESEARCH 



Effect of Irradiation on the Increase in Volume of Irradiated and Shielded 

 Sarcomas 



As we have found, irradiation inhibits the formation of nucleic acid 

 in the 2 hrs following the exposure almost to the same extent in the 

 shielded as in the irradiated sarcomas. On an earlier occasion^^^ we found 

 that in most cases the effect of X-rays which inhibits the formation of 

 nucleic acid decreases with time. The question therefore arose as to how 

 the effects of the X-rays on the shielded sarcoma and the unprotected 

 tumour are related at longer times, after irradiation has taken place. 



We have tried to answer this question by following the increase in 

 volume of the irradiated and shielded sarcomas. Some double sarcomas 

 which were inoculated in parallel into the two halves of the back (cf. 

 p. 755) and others, of which one was placed behind the neck and the 

 second near the tail on the right and left, respectively, were studied in 

 this experiment. The volume increase was measured for a few days 

 before, then for 4—6 days during irradiation and finally once every day 

 after completion of the irradiation. In order to permit sufficently accurate 



Table 10. — Volume Measurements on Irradiated and 



Shielded Sarcomas 



(Weight of rats about 150 gm Female. Inoculated on 3 November 1943. 



Irradiated on each second day normally with a total of 500 r each; 



a = anterior sarcoma, b = posterior sarcoma) 



<i) H. EuLER and G. Hevesy, Ark. Kern. 17 A, No. 30 (1944). 



