Preface 



It was both a considerable honour and a great pleasure for the 

 author to be invited to deliver one of the famous Chaifm Weizmann 

 Memorial Lectures at the Weizmann Institute in Rehovoth in April 

 1959. The high achievements of Chaim Weizmann, both as a states- 

 man and a scientist, make it difficult for any lecturer to give 

 Memorial lectures which are really worthy of his memory. Further- 

 more, the extremely high quality, as scientists and as men, of the 

 former Chaim Weizmann Memorial Lecturers has made the task 

 still more difficult for the present lecturer. In fact, the greatest trib- 

 ute which a scientist can pay to Weizmann's memory is to visit, to 

 admire and to love his country and the Institute which bears his 

 name in Rehovoth: he will find in the Institute the great qualities 

 of intellect, good organization and humanity which make the 

 charm and the greatness of Israel. For allowing him to make such a 

 visit to Israel, the author will always remain thankful to his 

 colleagues and friends of the Weizmann Institute. 



The present book is the presentation in written form of the last 

 Chaim Weizmann Lectures; there were three lectures which dealt 

 respectively with : (1) Ribonucleic acids and protein synthesis ; (2) 

 The role of ribonucleic acids in growth and morphogenesis ; (3) The 

 role of the cell nucleus in ribonucleic acid and protein synthesis. 

 Each of these lectures is presented here as a separate chapter, the 

 title of the whole book being: The Biological Role of Ribonucleic 

 Acids. The author wishes to acknowledge the fact that part of the 

 material presented here has already been published in his two 

 previous books : Biochemical Cytology (Academic Press, New York, 

 1957) and The Biochemistry of Development (Pergamon Press, 

 London, 1960). He also wishes to express his sincere thanks to his 

 secretaries, Mrs. E. De Saedeleer and Mrs. Y. Thomas, for their 

 efficient help in the publication of the manuscript and the prepa- 

 ration of the index. 



Brussels J. Brachet 



September 1960 



