PREFACE 



This book considers the chemical activities not only of animals but 

 alsi) those of plants and microorganisms. It aims to be a complete, 

 though brief, treatise on the whole field of biochemistry, stressing the 

 most important features of the subject. 



The first part deals with the materials of the cell, and the second with 

 tiie functions of the cell. Emphasis, however, has been placed on the 

 dynamic aspects of biochemistry as well as on its material features. 

 This purpose inevitably leads to a consideration of complex phenomena. 

 To make such phenomena understandable is no easy task, but the attempt 

 has been made. 



The subject matter is by no means beyond the comprehension of the 

 reader with only a general chemistry background, though best appre- 

 ciated and understood by the reader with a knowledge of organic chem- 

 istry. In view of the increased coverage (chapters on Nucleic Acids, 

 Hormones, and Biological Energetics) and the particular emphasis which 

 has been placed on metabolic reactions (chapters on Plant Metabolism, 

 Animal INIetabolism, and Metabolism of Microorganisms) , the present 

 work is well suited to more advanced readers. By careful selection of 

 chapters, the book should also prove useful to those interested in agri- 

 culture and home economics. 



The authors are indebted to their colleagues. Professors Casida, John- 

 son, Lardy, Meyer, Plant, Potter, Stahmann, and Williams for reading 

 one or more chapters of the manuscript and making many valuable sug- 

 gestions and criticisms of the book. They are doubly indebted to Pro- 

 fessor Burris for his chapter on Plant Metabolism, and to Professor 

 Plant for the two chapters on Digestion and Enzymes. The authors are 

 grateful to Dr. Mary Shine Peterson for the preparation of Tables 3-1, 

 4-2, 5-1, A-1, A-2, and A-3, and for critical reading of many of the 

 chapters in the book. 



In making these acknowledgments, the authors in no sense imply 

 that errors of omission and commission are to be charged to those named. 

 We apply to ourselves alone Byron's apostrophe to the ocean, "Upon 

 the watery plain, the wrecks are all thy deed." 



\y. H. Peterson 



F. M. Strong 



