PREFACE 



The exercises described in this laboratory manual are 

 arranged primarily for students of soil bacteriology, soil 

 chemistry and physics, and plant pathology. As far as 

 possible the experiments are planned to give quantitative 

 results. It is assumed that the student has had previous 

 training in general bacteriology and chemistry. 



The section entitled "Formulae and Methods" is intended 

 to present in a convenient form some of the more impor- 

 tant media and methods used in a study of soil bacteria. 

 The chemical methods employed are, with few exceptions, 

 those given in standard text-books. Much of the material 

 was collected and arranged by Mr. C. Hoffmann. 



In addition to the references given in the text, frequent 

 use has been made of the various manuals in bacteriology. 



Any suggestions in regard to improvement of the manual 

 will be welcomed. 



E. B. Fred. 



Madison, Wisconsin, 

 October, 1916. 



