FOREWORD 



hy 

 Sir Charles Harington, f.r.s., m.a., Ph.D. 



The advent of an entirely new tool of research is always 

 something of an event in science. There can be few more 

 striking illustrations of this than the story of the advances 

 in knowledge that have been made with the aid of isotopes. 

 The speed of development of this branch of research is due to 

 the realization of some of the potentialities of the method 

 even before separated isotopes were available, and to the 

 eagerness with which such pioneers as Hevesy exploited the 

 possibilities as soon as the discovery of induced radioactivity 

 made the preparation of minimal amounts of radioactive 

 isotopes possible ; it was still further increased by the 

 dramatic circumstances of the war-time work on nuclear 

 fission, which brought the technique within the reach of 

 laboratories in all branches of science. 



So far as biological science is concerned it was obvious at 

 the outset that the tracer isotope technique would find its 

 widest application in biochemistry ; it offered indeed a 

 method of attack on problems of intermediary metabolism 

 and biosynthesis which had hitherto been unapproachable. 

 It was unfortunate, though perhaps only natural, that the 

 sudden general availability of isotopes for biochemical 

 research should have led to sonje rather hasty experimenta- 

 tion in which the more obvious problems were studied without 

 deep thought. Such work, although it may provide quick 

 answers to some questions of interest, is far from representing 

 the best use of the new method. 



As time has passed, there has been more opportunity for 

 reflection, and the result of this is apparent in the nature of 

 the biochemical problems that are now being tackled with the 



