Radiation and Ascites Tumour Metabolism 217 



close agreement between the growth curve and the dilution 

 of DNA activity. The corresponding data for RNA and 

 proteins show appreciable deviations from expectation 

 assuming stability. However, an important difference is that 

 in the case of proteins a progressive loss of activity through 



PROTEIN 



100- 



St 



zi- 



o 



Oll. 



GLYCINE I:x 

 GLYCINE n: A 



-50 



cc 

 a. 



T 1 \ 1 T 1 T- 



12 3 4 5 6 7 



DAYS AFTER INOCULATION 



Fig. 2. Products of total number of free tumour cells and specific 



activity of the protein fraction. The initial value is taken as 



equal to 100. Two series of experiments. 



exchange and release from the once incorporated i*C-glycme 

 occurs (Fig. 2), as compared to an initial deviation only in the 

 RNA curve taking place between the collection of labelled 

 cells and the second day of growth of the inoculate. The 

 continuous loss of protein-bound ^^C is in agreement with the 

 observation of Greenlees. The activity released from cell 

 proteins is, however, not in a chemical form which can be 

 used for further synthesis of nucleic acids. We are led to this 



