Preface 



There are many mansions in the house that the Natural Sciences have 

 been building in the course of 400 years; but it has remained one edifice. 

 Although its architectural style may not be of one piece, combining, as it 

 does, the labors of so many generations, the very consistency of the struc- 

 ture makes difficult the coherent description of one wing without a distor- 

 tion of proportions. An arbitrary line of demarcation must, however, be 

 drawn in a book of the kind we are presenting here. 



The progress in our knowledge of nucleic acids has been unexpectedly 

 rapid in the past few years, and there is no reason to assume that it will 

 not continue. Until recently, the state of nucleic acid chemistry could be 

 compared to that in which protein chemistry found itself at the beginning 

 of this century. The principal constituents were known, at least in the two 

 nucleic acids that served as the prototypes; but a real insight into the order 

 and mode of their arrangement was lacking. All this has changed; the 

 nucleic acids are no longer regarded as mere pegs for the proteins. The large 

 number of publications, the multiplication of partial efforts, of fragmentary 

 reviews and symposia, make imperative an attempt at a detailed inventory 

 of our knowledge. 



This treatise tries to collect all the information at present available into 

 a single comprehensive work. It is divided into two main parts, covering 

 the chemical and the more biological or biochemical aspects of the subject, 

 respectively. The chemistry of the hydrolysis products of nucleic acids is 

 covered in Chapters 2, 3, and 4, and their separation and estimation in 

 Chapters 5 to 9. The two main types of polynucleotides are discussed in 

 Chapters 10 and 11. The nature of the chemical bonds in nucleic acids is 

 considered in Chapter 12, their physical properties in Chapter 13, and their 

 optical properties in Chapter 14. The principal absorption spectra pro- 

 vided in Chapter 14 are also reproduced, on a metric scale, on two folded 

 sheets that will be found in a pocket on the inside back cover of Volume I. 



The next chapter (15), which deals with the enzymes attacking nucleic 

 acids, forms the connecting link with the second main division of the book 

 which begins with a survey of the nucleic acid content of tissues, in Chap- 

 ter 16, and of cytochemical methods, in Chapter 17. The cell nucleus is 

 discussed in Chapters 18, 19, and 20, and the cytoplasm in Chapter 21. 

 The next four chapters cover the biosynthesis of nucleic acids and their 

 components. Nucleic acid metabolism is discussed in Chapter 26, and the 

 book ends with two chapters on the biological role of the two main types 

 of nucleic acid (Chapters 27 and 28). 



A collaborative undertaking, the only one possible at the present time, 



