CAROTENOIDS 



as is known, every important contribution which has appeared since 

 that date has been discussed. Two peripheral aspects of the subject 

 have, however, been omitted, namely (a) the qualitative and quantitative 

 changes which the carotenoids of plant materials undergo in storage or 

 during processing into food and (b) the carotene (pro-vitamin A) 

 requirements of different animal species ; it was felt that the former, 

 about which a great deal has been written, was too technological to be 

 suitable for inclusion in the present volume, whilst the latter is more 

 suitable for a monograph on vitamin A. 



The very wide distribution of the carotenoids in Nature suggests that, 

 in spite of the superficially diverse functions ascribed to them in 

 different living tissues, there may be some factor or property through 

 which all these functions will eventually be correlated ; any suggestion 

 as to the nature of this common property can perhaps come most 

 readily from a comparative approach. Apart from critically surveying 

 the literature this book has been constructed so as to focus attention on 

 comparative data and their possible implications. If the comparative 

 aspects do not always appear to have been given sufficient explicit 

 consideration it is because essential data are still lacking ; it may even 

 be hoped that when research workers realise fully the lacunae, they 

 will be stimulated to carry out investigations on comparative lines. If 

 this does occur then the author will feel that the book has served one 

 of its main purposes. 



To many biochemists the word ' carotenoid ' stimulates the mental 

 response * vitamin A precursor ' and no more. There is a need, which 

 it is hoped this book fulfils, to emphasize to all concerned, directly or 

 indirectly, with carotenoid biochemistry that a much wider view must 

 now be taken of these pigments and that in the course of elucidating 

 their biogenesis, metabolism, and functions, very significant advances 

 with wide implications for our understanding of living processes are 

 to be expected. 



My sincere thanks for considerable help during the writing of this 

 book are due to many friends and colleagues ; it should be emphasized 

 however, that none of them can be considered in any way responsible 

 for any peculiarities which may exist in the book. Professor R. T. 

 Williams (St. Mary's Hospital Medical School) read and criticized the 

 original typescript ; Mr. D. A. Coult (Department of Botany, The 

 University of Liverpool) read the section on plant carotenoids and 

 corrected many errors of nomenclature ; Dr. J. Glover (Department of 

 Biochemistry, the University of Liverpool) devoted considerable 

 time to correcting both the galley and the page proofs, and made many 

 valuable suggestions. Miss B. M. Morris and Miss M. W. Boggiano 



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