176 



J. N. Davidson 



of pentose and phosphorus estimations in the ribonucleo- 

 tide fraction suggest the presence of a phosphate ester 

 (or esters) other than the ribonucleotides (Davidson, Frazer 

 and Hutchison, 1951). 



Table I 



Concentrations and Activities of Phosphorus Compounds Obtained 



BY the Schmidt-Thannhauser Procedure from Rabbit Liver Two 



Hours after Injection of lOfxc. ^-P per 100 g. body weight 



Table II 



A Comparison of the Specific Activities of Phosphorus Fractions 

 Obtained from Rabbit Liver Homogenates by the Schmidt-Thann- 

 hauser Procedure with those of Nucleic Acids Isolated from the 



Same Material 



10 /iC. per 100 g. body weight were injected two hours before killing. 



Specific activities in cts./min./lOO /xg.P. 



In the second place, the specific activity of the phosphorus 

 in the ribonucleotide fraction is invariably much higher than 

 that of the phosphorus in isolated RNA, while the activity 

 of the DNA fraction is greater than that in isolated DNA 

 (Table II). 



