PREFACE 



TEXT-BOOKS and Manuals upon Bacteriology are, for the 

 most part, written by Bacteriologists whose investigations 

 and routine work are in the field of Pathological Bacteriology. 

 The descriptions in these text-books of methods suitable for 

 the examination of morbid human materials and for the study 

 of the pathogenic bacteria leave little to be desired on the 

 score of either lucidity or completeness. 



In marked contrast is the inadequate treatment given to 

 the bacteriological examination of water, air, foods and the 

 like. The description of their examination is either relegated 

 to a few pages at the end of the volume, where their treatment 

 is both scanty and incomplete, or, not infrequently, is omitted 

 altogether. This branch of bacteriology is of immense practical 

 importance and justifies a more extended treatment. 



The aim of this volume is to remedy this defect and to 

 make available a practical manual dealing not only with the 

 examination of these substances but also with the deductions 

 to be drawn from the bacteriological data obtained from their 

 examination. Much of the available information is only at 

 present to be found in original papers not always readily 

 accessible. 



The methods selected are, in general, those which I have 

 found to be of practical value and proved utility, while special 

 attention has been given to the difficult matter of the deductions 



