NUCLEIC ACID IN RETIIOGKADE SARCOMATA 737 



per cent. Thus, with a substantial autolytic decomposition of the tissue 

 phosphatides, a less pronounced formation of labelled phosphatides 

 takes place. The latter more subtle process can be almost quantitatively 

 suppressed by 0.01 mgm KCN, while the extent of autolysis is not at all 

 diminished by the presence of cyanide; a slight decrease of the rate of 

 autolysis being even observed. 



In our experiments^^) on the formation of labelled desoxyribosenucleic 

 acid in surviving slices of Jensen sarcoma, incubated at 37^ in a Ringer 

 solution containing labelled phosphate, we found, in experiments taking 

 4 hours, about 0.1 per cent of the desoxyribosenucleic acid molecules 

 present at the end of the experiment to be labelled. The desoxyribose- 

 nucleic acid content of such slices was found to be diminished by 25%, 

 due to autolysis, in the course of 24 hours at 20". 



In a retrograde sarcoma the tissue not involved in the necrotic process 

 is thus showing a almost normal desoxyribosenucleic acid formation. 

 Since in the retrograde sarcoma the percentage formation of labelled 

 desoxyribosenucleic acid is not appreciably lower than in the growing 

 sarcoma, we have to conclude that a growth of the intact parts of the 

 retrograde sarcoma takes place as well; possibly at a somewhat lower 

 rate as indicated by the figures of Table 2. 



In some of our earlier experiments we irradiated the rats all through 

 the experiment. In these experiments the rats were still fixed to a table 

 after the injection of the labelled phosphate had taken place. The ratio 

 of the specific activity of the desoxyribosenucleic acid P, to that of the 

 inorganic P of the sarcoma and the plasma respectively, was found in 

 some of these experiments to be much lower than in our usual experi- 

 ments, where the rats were fixed to a table during the irradiation, but 

 not after the injection of the labelled phosphate had taken place. The 

 low radioactivity found when the rats were fixed to a table, and irradia- 

 ted all through the experiment, was discovered not to be due to a cor- 

 respondingly diminished turnover of the desoxyribosenucleic acid under 

 the action of radiation, but mainly to a disturbance in the circulation 

 of the rat. We found, not in all, but in several of the control experiments 

 in which rats were fixed to a table without being irradiated, very low 

 activity figures for the desoxyribosenucleic acid. The disturbed circula- 

 tion results in a low ratio of the specific activity of the inorganic P of the 

 plasma and the sarcoma, which can become in such experiments with 

 disturbed circulation as low as ^/^q. In such cases a very appreciable 

 part of the inorganic P of the sarcoma is made up of extracellular inor- 

 ganic P. Furthermore, the disturbed circulation also influences the 

 resorption of the injected phosphate, and the difference between the 



^-^ L. Ahlstrom, H. Euler and G. Hevesy, Sv. Vet-Akad. Arkiv f. Kemi, A 

 21, No. 6 (1945). 



47 Hevesv 



