Preface 



These essays were written in honor of Hans Thacher Clarke, on 

 the occasion of his retirement as Professor and Chairman of the De- 

 partment of Biochemistry, College of Physicians and Surgeons, Colum- 

 bia University. Through their contributions to this volume, the 

 authors, all former students or academic associates of Professor 

 Clarke, sought to express their affection and esteem for him, and their 

 gratitude for his generous aid and counsel. If merit be found in these 

 essays, it is a consequence, in large measure, of the high standards 

 of chemical scholarship to which the authors were exposed, early in 

 scientific life, through their association with Professor Clarke. For 

 this opportunity to learn from him not only some of the facts of sci- 

 ence but something of its spirit as well they are deeply grateful. 



The essayists were accorded free rein in regard to subject and style. 

 The articles, for the most part, are neither reviews nor experimental 

 reports. Some are critical discussions of the status of a biochemical 

 problem at the time of writing, whereas others are frankly speculative 

 or deliberately provocative. The absence of editorial directive permits 

 the discerning reader to glimpse the personalities behind the printed 

 page and to contrast diverse approaches toward scientific goals. 

 Nature sometimes yields her secrets upon the skillful use of but a 

 few tools; frequently, the techniques of many scientific disciplines are 

 needed. But always there is the excitement of the search. 



Eael A. Evans, Jr. 

 Joseph S. Fruton 

 Samuel Graff 

 David Shemin 



New York 



November, 1955 



