vi NITROGEN METABOLISM 



organism which has been studied, but the reader's search 

 for additional information should be aided by the books re- 

 commended for general reading and the detailed biblio- 

 graphy appended to each chapter. 



It is with very great pleasure that I record my thanks to 

 Dr. S. R. Elsden for his interest in the preparation of this 

 monograph and to him and Dr. J. L. Peel for reading the 

 drafts of the various chapters and making many helpful sug- 

 gestions. I am also grateful to Dr. E. F. Gale, F.R.S., for 

 reading the completed manuscript. 



Sheffield 



1953 



