viii Preface 



control them and to make their activities widely useful 

 to human society. 



The present volume is an attempt to treat, in a 

 simple way, of the bacteria as they concern life 

 in the country. It is an attempt to discuss the char- 

 acter of the bacteria in air, water, sewage, manure, 

 soil, and food' products. Technical terms and expres- 

 sions have been eliminated as far as practicable, and 

 it is hoped that the general reader may find the book 

 an aid in the understanding of the bacteriological 

 problems as they affect the daily tasks on the farm. 



The author wishes to express his indebtedness to 

 Messrs. Percy E. Brown and Herbert Seidman for their 

 assistance in the preparation of the index; and to 

 Dr. Edward B. Voorhees for the permission to use a 

 number of the photographs that appear in this volume. 



JACOB G. LIPMAN. 



New Jersey Experiment Stations, 



New Brunswick, N. J. 



June 22, 1908. 



