AUTHOR'S FOREWORD 



The first monograph on carotenoids was written in 1922 by L. S. 

 Palmer {Carotenoids and Related Pigments, New York). In view 

 of the state of the subject at the time, this author could say rela- 

 tively little about the chemistry of these natural pigments and his 

 work therefore consisted mainly of a summary of the knowledge 

 then available concerning the distribution and the biological signif- 

 icance of the carotenoids. 



In 1934, L. Zechmeister's excellent book Carotinoide (Berlin) 

 appeared, in which the great advances which had been made in the 

 chemistry of these polyene pigments during the period 1927-1934 

 were described. Since then, the unravelling of the chemical nature 

 of the carotenoids has further advanced and progress has also been 

 made in the elucidation of their biological significance. A great 

 deal of material has thus accumulated during a relatively short 

 period. 



It was the desire to sift and collate the extensive literature on 

 carotenoids which led to the writing of the present monograph 

 on this class of natural pigments. Special attention has been paid 

 not only to the chemistry but also to the distribution and biological 

 significance of the carotenoids. It is hoped that the numerous tables 

 will help to clarify the relationships between the different pigments. 



P. Karrer, E. Jucker 



Zurich, August 1948 



