VI PREFACE 



many individuals during a considerable period of time, it is impossible to 

 render a full account of the writer's indebtedness. Wherever direct use has 

 been made of the experience and methods which others have formulated, an 

 attempt has been made to render definite credit to the source. When such 

 accounts of experience are used without citation of publication, credit is, in 

 most cases, due to the columns of the Pacific Rural Press, a journal which 

 has been the chief medium for the publication of information of this kind 

 for the last forty-three years. EDWARD J. WICKSON. 



University of California, Berkeley, May, 1913. 



