4 J. N. DAVIDSON AND E. CHARGAFF 



"guanylic acid" which could be precipitated by acetic acid. This material 

 was subsequently shown by the work of Feulgen,^'' of E. Hammarsten,^^ 

 of Hammarsten and Jorpes,^^ and Jorpes^^"" to be a pentose polynucleotide. 

 From such pancreas material also, Jones and Perkins^® isolated, in crystalline 

 form, the pentose nucleotides of adenine, guanine, and cytosine and re- 

 ported the presence in spleen and liver of a substance resembling the 

 guanylic acid of the pancreas. It was at this time (1924) that the idea be- 

 gan to develop of a more widespread occurrence of pentose nucleic acids in 

 animal tissues than had previously been supposed. 



It had been known for a long time that, in addition to the coenzyme nu- 

 cleotides, pentose nucleotides presumably derived from polynucleotides 

 were present in animal tissues such as chick embryo," mammary gland,^^' ^^ 

 haddock^" and sea urchin^^ eggs, and even spleen and liver.^^' ^^ All this evi- 

 dence led to the suggestion made by Jones and Perkins-^ in 1924 and sup- 

 ported by Jorpes^* in 1928 that "the distinction between animal and plant 

 nucleic acid will in future not be so definitely drawn." Further support for 

 this view was provided by evidence for the presence of deoxyribonucleic 

 acids in plant tissues. ^^"'^ 



As the result of the development of Brachet's ribonuclease test [Chapter 

 17], the presence of pentose nucleic acids was demonstrated histochemically 

 in amphibia,"-^'' in the anterior pituitary of the growing rat and guinea pig,^' 

 and in toad's eggs.'*'^ At the same time the pioneer work of the Caspersson 



2" A. Feulgen, Z. physiol. Chem. 108, 147 (1919-20). 

 " E. Hammarsten, Z. physiol. Chem. 109, 141 (1920). 



22 E. Hammarsten and E. Jorpes. Z. physiol. Chem. 118, 224 (1922). 



23 E. Jorpes, Biochem. Z. 151, 227 (1924). 



2* E. Jorpes, Acta Med. Scand. 68, 253, 503 (1928). 



25 E. Jorpes, Biochem. J. 28, 2102 (1934). 



26 W. Jones and M. E. Perkins, /. Biol. Chem. 62, 290 (1924-25). 



27 H. O. Calvery, /. Biol. Chem. 77, 489 (1928). 



28 R. Odenius, Jahresber. Fortschr. Thierchem.. 30, 39 (1900). 



29 J. A. Mandel and P. A. Levene, Z. physiol. Chem. 46, 155 (1905). 



30 P. A. Levene and J. A. Mandel, Z. physiol. Chem. 49, 262 (1906). 



31 K. C. Blanchard, J. Biol. Chem. 108, 251 (1935). 



32 P. Thomas and C. Berariu, Compt. rend. soc. biol. 91, 1470 (1924). 



33 R. Feulgen and H. Rossenbeck, Z. physiol. Chem. 135, 203 (1924). 



34 A. Kiesel and A. N. Belozerski, Z. physiol. Chem. 229, 160 (1934). 



35 A. N. Belozerski, Biokhimyia (U. S. S. R.) 1, 253 (1936); Compt. rend. acad. sci. 

 U. R. S. S. 25, 751 (19,39). 



36 M. Behrens, Z. physiol. Chem. 253, 185 (1938). 



37 J. Brachet, Arch. biol. (Liege) 44, 519 (1933). 



38 J. Brachet, Arch. biol. (Liege) 48, 529 (1937). 



39 J. Brachet, Arch. biol. (Liege) 51, 151, 167 (1940). 



" J. Brachet, Compt. rend. soc. biol. 133, 88, 90 (1940). 



" L. Desclin, Compt. rend. soc. biol. 133, 457 (1940). 



« T. S. Painter and A. N. Taylor, Proc. Natl. Acad. Sci. U. S. 28, 311 (1942). 



