Published online by Cambridge University Press: 11 June 2012
The classical view that, of the two known types of nucleic acid, desoxyribonucleic acid (thymonucleic acid) is characteristic of animal tissues and ribonucleic acid (pentose nucleic acid) of plant tissues, was established by the work of Kossel and others and upheld as a fundamental generalisation by Jones (1920). This view, which was current for over thirty years, has had to be abandoned in the light of more recent evidence. Not only has desoxyribonucleic acid been found in plant tissues, but ribonucleic acid has been isolated from the pancreas (Jorpes, 1928, 1934) and has been shown to be widespread in animal tissues (Davidson and Waymouth, 1943, 1944 a, b). Ribonucleic acid has been isolated, also, from liver tissue, in which it is present in much larger amounts than is desoxyribonucleic acid (Davidson and Waymouth, 1944 c).