PREFACE TO FIFTH EDITION. 



Knowledge in claiming, like all other technical indus- 

 tries, has grown mainly out of experience. Many facts 

 have been learned by observation, but the why of each is 

 frequently shrouded in mystery. 



Modern dairying is attempting to build its more accu- 

 rate knowledge upon a broader and surer foundation, and 

 in doing this is seeking to ascertain the cause of well- 

 established processes. In this, bacteriology is playing an 

 important r61e. Indeed, it may be safely predicted that 

 future progress in dairying will, to a large extent, depend 

 upon bacteriological research. As Fleischmanu, the emi- 

 nent German dairy scientist, says: "The gradual abolition 

 of uncertainty surrounding dairy manufacture is the pres- 

 ent important duty which lies before us, and its solution 

 can only be effected by bacteriology." 



It is therefore natural that the subject of Dairy Bacteri- 

 ology has come to occupy an important place in the cur- 

 riculum of almost every Dairy School. An exposition of 

 its principles is now recognized as an integral part of 

 dairy science, for modern dairy practice is rapidly adopt- 

 ing the methods that have been developed as the result of 

 bacteriological study. The rapid development of the sub- 

 ject has necessitated a frequent revision of this work, and 

 it is gratifying to the writer that the attempt which has 

 been made to keep these Outlines abreast of bacteriological 

 advance has been appreciated by students of dairying. 



While the text is prepared more especially for the prac- 



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