CONTENTS 



CHAP. PAGE 



PREFACE V 



I INTRODUCTION I 



II AMINO- ACID CATABOLISM lO 



III NITRIFICATION AND DENITRIFICATION 32 



IV THE FIXATION OF NITROGEN 45 



V SYNTHESIS OF AMINO-ACIDS 6o 



VI ABSORPTION OF AMINO-ACIDS BY MICRO-ORGANISMS 8o 



VII PEPTIDES AND PROTEINS 95 



VIII PROTEOLYTIC ENZYMES 112 



IX NUCLEOTIDES AND NUCLEIC ACIDS 1 26 



X MODE OF ACTION OF CHEMOTHERAPEUTIC AGENTS I45 

 INDEX 159 



PLATES 



FACING PAGE 



I SYNTROPHISM AMONG ARGININE REQUIRING 



MUTANTS OF ESCH. COLI 69 



II ULTRAVIOLET PHOTOGRAPH OF CHROMATOGRAM 



SHOWING SEPARATION OF PURINES AND PYRIMI- 

 DINES IN YEAST NUCLEIC ACID I31 



III PHOTOMICROGRAPHS OF A COLON BACILLUS BEFORE 



AND AFTER TREATMENT WITH NUCLEASES 1 33 



ao9o6 



