viii PREFACE 



determining the completion of the task which was commenced nine 

 years ago. 



The general survey of synthetical chemistry made possible by the 

 present work will help to bring into prominence the extreme im- 

 portance of the chemist and physiologist working hand in hand for 

 the future advancement of knowledge in this domain. Had time and 

 space permitted, I should have liked to discuss from the chemical point 

 of view the different hypotheses which have from time to time been 

 advanced by chemists and physiologists in explanation of the vital 

 synthesis of various compounds or groups of compounds. Such dis- 

 cussion, even had I possessed the necessary qualifications as a physiolo- 

 gist, would however have further delayed publication. This part of 

 the work may well be left over for future treatment, and will gain 

 rather than suffer in importance by allowing the facts to accumulate 

 and mature. I am not without hope that the present rdsumd will 

 materially assist any future discussion of the problems of Biochemistry. 

 As it stands, the work must be taken simply for what it professes to 

 be a bare record of the synthetical achievements of generations of 

 workers arranged with a distinct biochemical bias. 



At the outset I had also contemplated the interpolation of chemical 

 reactions and schemes, showing by the usual formulas the genetic 

 relationships between each vital product and its generators. This 

 likewise was abandoned when it was realised that such additions 

 would have expanded the work to an inordinate size, and, further, 

 that the chemical mechanism of these transformations was often 

 imperfectly understood or had been explained only in a tentative 

 way. Here again, therefore, it has been thought better on the whole 

 to limit the work to statements of fact only, because, while the pro- 

 duction of one compound from another is an actual achievement, the 

 chemical explanation of the process must necessarily, with the develop- 

 ment of our theoretical notions, be subject to modification. As exer- 

 cises in chemical theory the pages of this compilation will be found to 

 furnish an overwhelming mass of material, and the original publica- 

 tions from which the facts have been gleaned can always be consulted 

 by those who wish to enter more fully into this aspect of the 

 subject. 



In offering this book as a work of reference embodying only records 

 of facts, it must of course be understood that my task has been simply 

 that of a compiler, and that I do not hold myself responsible for any 

 of the statements made by investigators. It is not in any sense to be 

 regarded as a critical work, and my whole object has been simply to 



