738 



ADVENTURES IN RADIOISOTOPE RESEARCH 



end and the mean value of the specific activity of the tissue inorganic P 

 during the experiment becomes very appreciable. 



That the fixing of the rat on to the table all through the experiment 

 does not necessarily interfere with the normal circulation, is seen from 

 the following activity ratios: 



Percentage ratio of the 

 specific activity of the 

 nucleic acid P to that of 

 the inorganic sarcoma P 



Percentage ratio of the 

 specific activity of the 

 nucleic acid P to that of 

 the inorganic plasma P 



Control 



Fixed to table 



1.47 

 1.54 



In this case the muscles of the rat presumably relaxed. That the effect 

 of fixing can obstruct the circulation to a high degree, is seen from the 

 following figures: 



Fixed to tab'.e 0.234 0.1 II 



In our later experiments, in which the animal was irradiated all 

 through the experiment, we placed the rat in a beaker coated with 

 black paper. The X-ray dose administered was controlled by placing a 

 micro-ionising chamber on the sarcoma. In these experiments no appre- 

 ciable difference was found between the results obtained either when the 

 irradiation took place only before the injection or when it took place 

 all through the experiment; as seen in Table 4. 



Table 4. Irradiation of Rats in Glass Beaker With a Total Dose of 1000 r 



Desoxyribosenucleic Acid Formation in Benzpyrene Sarcomata 



In a few cases we determined the rate of renewal of desoxyribosenucleic 

 acid in sarcomata obtained by grafting tumour tissue produced by 

 treatment of rats with benzpyrene. The results obtained are seen in 

 Table 5. 



