NUCLEIC ACID IX SARCOMA SLICES 779 



(a) 22.3; 



(b) 20.8; 



and per gm tissue 



(a) 6.76; 



(b) 5.42. 



The presence of oestrone cannot, Ihereforo, substantially affect the 

 synthesis of nucleic acid molecules. 



Formation of Nucleic Acid in the Presence and Absence of Caffeine 



In this experiment 5.52 gm (arrangement (a)) and 5.53 gm (arrange- 

 ment (b)) of tissue sections were immersed in 19.5 cm^ of blood which 

 contained 1 mgm of active sodium phosphate; 0.66 cm^ of physiological 

 saline solution containing 20 mgm of caffeine was added to (b), and the 

 same volume of saline solution without caffeine to (a). Time of ex- 

 periment, 4 hr, temperature 37° C. The results found were: 



Activity of 1 mgm nucleic acid P as a percentage of the activity of 1 

 mgm of free sarcoma P: 



(a) 0.104; 



(b) 0.147. 



Percentage of the activity of the plasma plus the free P activity of 

 the tissue sections present at the end of the experiment as free P in the 

 tissue: 



(a) 21.6; 



(b) 22.2; 



and per gm of tissue 



(a) 3.91; 



(b) 4.02. 



Caffeine does not, therefore, significantly affect the formation of radio- 

 active molecules of nucleic acid. 



Formation of Nucleic Acid in the Presence and Absence of Colchicine 



Tissue sections (6.5 and 6.0 gm in experiments (a) and(b), respectively) 

 were immersed in 18.5 cm^ of blood to which had been added 1 mgm of 

 radioactive sodium phosphate; 4 mgm of colchicine was also added to 

 solution (b). Time of experiment, 4 hr, temperature, 37° C. The percent- 

 age ratio for 1 mgm of nucleic acid P to that of 1 mgm of free tissue 

 P was: 



(a) without colchicine 0.175; 



(b) with colchicine 0.172. 



