PREFACE IX 



for reading the Chapter on Anaerobic Bacteria; to Mr. D. W. Cutler, 

 Mr. H. Sandon, of the Rothamsted Experimental Station, and Prof. 

 C. A. Kofoid, of the University of California, for reading the Chapter on 

 Protozoa; to Dr. N. Cobb and Dr. Steiner, of the Bureau of Plant 

 Industry, for reading the Chapter on Soil Invertebrates; to Dr. O. 

 Meyerhof, of the K. Wilhelm Institute, Berlin, for reading the Chapter 

 on Energy Transformation; to Dr. T. B. Osborne, of the Connecticut 

 Agricultural Experiment Station, for reading the Chapter on Protein 

 Transformation; to Mr. A. Bonazzi, of Cuba, for reading the Chapter on 

 Non-symbiotic Nitrogen Fixation; to Dr. R. L. Jones, of the University 

 of Wisconsin, for reading Chapter XXX; to Dr. E. B. Fred, of the Uni- 

 versity of Wisconsin, for reading the Chapter on Nitrate-reducing 

 Bacteria; to Prof. D. R. Hoagland and Dr. W. P. Kelley, of the Uni- 

 versity of California for reading Chapters 24 and 25 respectively; to 

 the members of the Soil Microbiology Division of the New Jersey Ag- 

 ricultural Experiment Station, especially to Dr. J. G. Lipman and 

 Dr. R. L. Starkey, for reading various parts of the book, and to all 

 those who have generously allowed the use and reproduction of the 

 various illustrations in the text. 



Selman A. Waksman. 



August 25, 1826. 



New Brunswick., N. J., U. S. A. 



