PLATE II. — Separation and identification of the purines and pyrim- 

 idines in yeast ribonucleic acid (YNA): YNA hydrolysed for 

 2 hr. in 70 %HC104 at 100° C: solvent system isopropanol 

 (65% v/v) and 2N-HC1 (final concentration): G, A, C, and 

 U pure samples of guanine, adenine, cytosine and uracil. 

 Photograph obtained by placing chromatogram over reflex 

 document paper and exposing to ultraviolet light. ST. de- 

 notes starting line 



