TRANSLATOR'S FOREWORD 



In the present English edition of Professor P. Karrer's and Dr E. 

 Jucker's book, a number of corrections have been made, and a 

 certain amount of new material, covering some of the more impor- 

 tant investigations published since the appearance of the Swiss 

 edition, has been added. 



I am indebted to my wife for assistance in preparing the trans- 

 lation, and to Dr B. C. L. Weedon for help in checking the proofs. 



E. A. Braude 

 London, January 1950 



