RIBOSENUCLEIC ACID liST THE JENSEN-SARCOMA OF THE RAT 687 



Summary 



Radiopbosphorus is injected into full-grown rats inoculated with Jensen-sarcoma. 

 The specific activity of 1 mgm ribosenucleic acid extracted from the Jensen-sarcoma 

 at the end of 2 hours from the begimiuig of the experiment was found to be 6 

 per cent of the average specific activity of the inorganic P of the sarcoma through- 

 out the experiment. On the basis of the assumption that the precursor of the 

 ribosenucleic acid P is either the cellular inorganic P of the sarcoma or organic 

 P which is rapidly brought in exchange equilibrium with the ceUular inorganic P, 

 the above figure represents the percentage of the new-formation of the ribose- 

 nucleic acid present in the Jensen-sarcoma in the course of 2 hours. 



Out of 6 labelled ribosenucleic acid molecules 1 represents additional formation 

 due to growth of the sarcoma during the experiment, while the formation of 

 roughly 5 new molecules is compensated by the simultaneous disappearance of 5 

 "old" ribosenucleic acid molecules. 



The ratio between the specific activity of the ribosenucleic acid P and the 

 specific activity of the desoxyribosenucleic acid P of the Jensen-sarcoma is 2.4. 



