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ADVENTURES IN RADIOISOTOPE RESEARCH 



uncorrected values of the "percentage renewal" are set out). The ratio 

 between the average and end- value of the specific activity of the sar- 

 coma inorganic P can vary appreciably from sarcoma to sarcoma. These 

 variations influence unfavourably the accuracy of the determination of 

 the percentage new-formation of the nucleic acids in the sarcoma. 



It may be assumed that the increase in the ribosenucleic acid content 

 of the growing sarcoma during the course of the experiment (2 hours) 

 amounts to about the same value as the increase of the desoxyribose- 

 nucleic acid, i.e., 0.9 per cent of the amount present. Out of the 6 per 

 cent newly formed ribosenucleic acid during the experiment, i/ is thus 

 due to additional formation of ribosenucleic acid, while ^/g are due to 

 renewal of old molecules. 



The value of the rate of renewal of ribosenucleic acid in the Jensen- 

 sarcoma is about twice of the corresponding value (3.5) determined in 

 the liver. 



The Nucleic Acid P Content of the Jensen- Sarcoma 



From the colorimetric determination of the P of the desoxyribose- 

 nucleic acid and the ribosenucleotides we computed the values set out 

 in Table 4. 



The ratio between the desoxyribose and ribosenucleic acid of the 

 Jensen-sarcoma is appreciably smaller than that between those in liver 

 and most other organs. This is mainly due to the large desoxyribose- 

 nucleic acid content of the sarcoma tissue. 



Table 4. — Nucleic Acid P 

 Content of Jensen-Sarcoma 



mgm% in fresh tissue 



Desoxyribose P 



42 



54 



Ratio 



Ribose P 



Ribose P 



64 

 87 



Desoxyribose P 



= 1.7 



