158 



D. Wright Wilson 



Table V shows the specific activities of compounds isolated 

 after incubating some human tumours with radioactive 

 orotic acid. The specific activity of uridylic acid in the first 

 experiment was the highest we have obtained but, as different 



Table V 

 Human Tumours Incubated with 3 mg. of [2-i*C] Orotic Acid 



tissues vary considerably, we do not feel that it is necessarily 

 characteristic of this tissue. However, the ratios of specific 

 activities of uridylic and RNA cytidylic acids seem to be 

 significant for tumours. The ratios for tumours range from 

 7 to 11, while for normal tissues the ratios range from 2 to 4, 

 although normal spleen gave ratios as high as 7. The specific 

 activities of thymidylic acid were low. 



The specific activities of the bases from the nucleic acids of 

 regenerating liver are given in Table VI. Regenerating liver 

 has been studied because it is a rapidly growing tissue, as are 



Table VI 



Regenerating Liver Incubated with 3 mg. of [2-i*C] Orotic Acid 



♦Eluted from Resin column with 01 N HCl. 

 tEluted from Resin column with 01 N HCl. 



