PREFACE 



Many excellent books on vitajnins have already been published, but 

 so rapid is the expansion of knowledge in this field that constant revision 

 is necessary to keep them up to date. The task of assimilating new 

 knowledge becomes progressively more difficult with each year that 

 passes and a complete survey must necessarily become more and 

 more voluminous. In the absence of some method of regularly 

 revising existing monographs, the scientific worker must keep himself 

 informed of new developments by a close study of the original litera- 

 ture, abstracts or periodical summaries such as the Annual Reports 

 of the Chemical Society, or he must be content to rely on the pub- 

 lication of occasional reviews or symposia in which particular aspects 

 of the subjects are discussed. 



Hitherto, no book devoted exclusively to a study of the vitamin B 

 complex has been published. Yet there is much to be said in favour 

 of thus restricting the field of inquiry. Perhaps the strongest argimient 

 is the impossibility of adequately surveying the whole group of 

 vitamins within the compass of one volume. And what more natural, 

 in this event, than to confine the study to the group of water-soluble 

 vitamins now known as the vitamin B complex which, after all, 

 contains all the newly characterised vitamins ? Apart from a his- 

 torical connection, the members of this group have little in common 

 with the fat-soluble vitamins or with vitamins C and P, whereas 

 nearly all of them have a strong family likeness, resembling one 

 another closely in their distribution in foodstuffs, in their biological 

 effects on animals, plants, insects and micro-organisms, and in their 

 biochemical fimctions. One of the main objects of this book is to 

 stress this close relationship, although the mode of treatment adopted, 

 that is, the discussion of each vitamin in turn, tends perhaps to stress 

 the distinctive characteristics of each rather than their similarities. 



I first became interested in the vitamin B complex about the year 

 1935 or 1936, when the synthesis of vitamins B^ and Bg was reported, 

 and I have maintained this interest ever since. I have followed closely 

 every development in this field and have myself been engaged in the 

 isolation, production and assay of the most important members of 

 the complex and, in recent years, I have been particularly concerned 

 with the relation between the B vitamins and chemotherapy. My 

 qualifications for writing this monograph are therefore an intimate 

 association with various aspects of the vitamin B complex, a convic- 

 tion that it forms a group of substances of outstanding biological 



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