EFFECT OF X-RAVS OX XUCLEIC ACID IN JENSEN-SARCOMA 



703 



the effect of irradition on Ihe formation of radioactivelylabelled nuc- 

 leic acid is ]ess pronounced. 



In five of the thirty-four sarcomas irradiated with more than 450 r 

 we were unable to detect any effect of irradiation on the formation of 



Table 7. — Nucleic Acid Metabolism in Unirradiated, Slightly Irradiated 

 (with less than 450 r) and More Strongly Irradiated (more than 450 r) Jensen 



Sarcoma 



nucleic acid. One of these sarcomas was irradiated with 1730 r, a second 

 with 1025 r, a third with 620 r and the remaining two with 465. Presum- 

 ably these sarcomas were more resistant to the action of radiation. In 

 the investigation of the growth of irradiated sarcomas after transplanta- 

 tion, it was found that the individual sarcomas vary in sensitivity toward 

 the action of radiation. Russ and Scott^^\ for example, state that of 

 one hundred Jensen rat sarcomas irradiated with 1000 r, seventy-five 

 recovered, and Suguria^ states, with regard to the sensitivity of the 

 closely related "sarcoma 180", that only half of the sarcomas withered 

 after irradiation with 1000 r. 



In most cases the difference in the formation of radioactively labelled 

 (and thus newly formed) nucleic acid molecules in unirradiated and 

 irradiated sarcomas is so striking that an unirradiated sarcoma can be 

 distinguished from an irradiated one by just placing the sample under 

 the counting tube. Complete suppression of the formation of active 

 nucleic acid molecules cannot of course be achieved even by using very 

 powerful doses. For example, after the most effective irradiation with 



IS. Russ and G. M. Scott, Brit. J. Radiol. 13, 267 (1940). 

 2K. SuGURiA, Radiology 29, 352 (1937). 



