Preface 



Since 1955, when the first, two volumes of this treatise were published, 

 knowledge relating to the chemistry and the biological importance of the 

 nucleic acids has continued its vigorous growth; a progress which, however, 

 has not been uniform in all directions. After much discussion and deliber- 

 ation we came to the conclusion that, while an entirely new edition was not 

 yet justified, a Way could be found to prevent the premature obsolescence of 

 a compendium of the kind offered by us. It was decided to provide what 

 could be called a "diagonal supplement," i.e., a selection of chapters cutting 

 across, as it were, the systematic arrangement observed in the preceding 

 volumes. Care was taken to choose topics that had not received sufficient 

 emphasis before or that had acquired particular importance since the publi- 

 cation of the earlier volumes. Moreover, a slight shift in perspectives was 

 also made easier by the decision to limit contributions to the present volume 

 to authors who had not collaborated in the preceding ones. 



Of the twelve articles presented here, the first six, Chapters 29 to 34, 

 deal with topics related to Volume I of the parent work, whereas Chapters 

 35 to 40 are thematically near the subject matter treated in Volume II. 

 As regards the question of nomenclature and abbreviations, we are aware 

 of the proposals which have been made by the Nomenclature Commission 

 of the International Union of Pure and Applied Chemistry, Section of Bio- 

 logical Chemistry; but until these have been universally accepted we have 

 felt it best to let each author decide and define the manner best suited to 

 his purpose. 



April, 1960 Erwin Chargaff 



J. N. Davidson 



