viii prp:facf, 



and the sites of its synthesis, organization, and function. The last three 

 chapters deal with the genetic aspects of protein synthesis and the tran- 

 scription of the genetic code into functional entities. A few of the areas 

 not covered will be obvious; for example, exciting conceptual develop- 

 ments on control mechanism in the transcription of the genetic code arc 

 touched lightly. The cell-free synthesis of UNA, which was advancing 

 so rapidly as this volume was written, is yet to be covered in detail. 

 Another topic, genetic recombination, which is of deep concern and 

 great significance to geneticists, has been largely ignored, jicrhaps with 

 good reason. A major conceptual revolution, with some indication that 

 the topic can be treated in molecular terms, is now in the making. 



The chapters were not intended as comprehensive reviews, but repre- 

 sent personal accounts of developments best known to each writer, who 

 in all cases was involved in making significant advances in the respective 

 areas. However, there was an attempt to present a balanced view, to cite 

 related findings and most of all to write a readable and up-to-date 

 account. In a field which moves as fast as molecular genetics, publica- 

 tions tend to be outdated before they are off the press. To circumvent 

 this, in jiart at least, we hope we have covered some material of lasting 

 importance, presented the newest developments known to us while writ- 

 ing, and in some cases looked into the future with a bit of speculation 

 that will hopefully prove stimulating and i^roductive. 



The Editor is indebted to the contributors who paused in their 

 research long enough to make their contribution and who responded to 

 the stated objective of finishing tlie manuscripts together so that all of 

 the chapters would have the same degree of timeliness, except for the 

 limitations imposed by the nature of the material covered. For expediting 

 the work and for skillfully managing many of the technical details, the 

 publishers are to be given much of the credit. To all of those who 

 contributed by supplying unpublished figures and data or made material 

 in press available to the various authors, special credit is due. ]\Iany of 

 them are acknowledged in the various chapters, but for contributions 

 of unpublished material to Chapter II, I wish to thank Joseph G. Gall 

 of the University of Minnesota, George D. Pappas and Philip W. Brandt 

 of Columbia University, and Oscar Tj. Miller, Biology Division, Oak 

 Ridge National Laboratory. 



J. Herbert T.wlor 



