CHAPTEE IX 



GENERAL PARTICULARS AND PRELIMINARY PROCEDURE 



The bacteriological examination of milk even up to a few 

 years ago could not be said to be very satisfactory, and 

 indeed, apart from tuberculosis, very little was systematically 

 done, while in regard to the procedures that were carried out 

 there was neither uniformity of method nor consensus of 

 opinion as to what was desirable. Even at the present time 

 it is by no means on a uniform or satisfactory basis. 



The bacteriological examination of milk may be utilised 

 to give information in the three following directions : 



1. To measure the degree of contamination of the milk 

 from faecal and other sources and its general bacterial con- 

 tent. 



2. To ascertain the presence or absence of definite disease- 

 producing organisms, e.g. B. diphtheriae, B. tvhmxulo&is, B. 

 typhosus. 



3. To obtain evidence as to the healthiness of the milk- 

 producing apparatus of the cows which supply the milk. 



The procedures to be used will obviously require to be 

 varied according to the purpose and objects of the examina- 

 tion. The different methods are considered in detail in the 

 following chapters. 



The chemical examination of milk is fully dealt with in 

 numerous works dealing with that aspect of the subject and 

 is not described in this book. The only chemical procedures 

 dealt with are those, such as the detection of preservatives or 

 the acidity estimation, which are intimately related to the 

 bacterial content, or which have been used as rough indicators 

 of the degree of bacterial contamination. 



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