PREFACE 



This laboratory manual has been designed for students in 

 General Microbiology, and especially for those working with soils 

 or with organisms isolated from the soil. Although various 

 exercises are described primarily for students in soils, the methods 

 of isolation and cultivation of bacteria, fungi, actinomyces, 

 algae and protozoa, and the determination of the biochemical 

 activities of these organisms can be used by the student in 

 General and Agricultural Microbiology. Special attention has 

 been paid to the physiology of microorganisms, including the 

 various so-called fermentation processes, in an attempt to bring 

 out not only the qualitative but also the quantitative relation- 

 ships of the various organisms. 



It is assumed that the student has had previous training in 

 general botany, zoology, bacteriology and chemistry; a knowledge 

 of organic and physical chemistry, of mycology, and of proto- 

 zoology will prove of great assistance in carrying out the experi- 

 ments and in understanding the results. 



Out of the numerous media suggested for the cultivation of 

 non-pathogenic organisms, the authors selected the simplest, 

 preferably the synthetic inorganic media, and those that have 

 been found to be most useful. It is impossible to give all the 

 chemical methods of analysis employed in microbiological 

 investigations. Only a few of the most essential methods, 

 dealing largely with the transformations of carbon and nitrogen, 

 and to a less extent of phosphorus and sulphur, have been 

 described. 



In addition to references given in the text, frequent use 

 has been made of the various nianuals in bacteriology, a list 

 of which is appended. 



The authors are indebted to their associates for many helpful 

 suggestions, especially to Dr. I. L. Baldwin, Miss Ehzabeth 

 McCoy, Dr. J. Blom, and Dr. R. L. Starkey. 



Madison, Wis. ^dwin Broun Fred. 



New Brunswick, N. J. Selman A. Waksman. 



November, 1928. 



