CHAPTER XII 



MEDIA MAKING AND APPARATUS REQUIRED FOR 

 BACTERIAL ANALYSIS OF MILK 



METHODS FOR MAKING MEDIA. 



THE Committee on Standard Methods of Bacterial Milk 

 Analysis of the American Public Health Association, Lab- 

 oratory Section, have recommended that methods of the 

 Committee on Standard Methods of Bacterial ani 

 Chemical Water Analysis of the American Public Health Associa- 

 tion, Laboratory Section (with two modifications only, noted be- 

 low), be adopted for official work in counting bacteria in milk; the 

 object being to secure uniformity of results in all laboratories de- 

 voted to this task. These methods are by no means to supersede any 

 found valuable by individual investigations for particular purposes,, 

 but are urged for adoption for official counts of certified, inspected 

 or market milk, and for such investigations as relate directly to com- 

 parative counts of different classes of milks, at different ages, etc. 

 Recently (Dec. 31, 1907), they have been recommended also by the 

 Committee on Methods of Identification of Bacterial Species, of the- 

 Society of American Bacteriologists, for species work. These- 

 methods so far agreed upon are given in the following pages. 



NUMERICAL DETERMINATION OF BACTERIA IN MILK. 



(From preliminary report of the Committee on Standard methods 

 of Bacterial Milk Analysis.) * 



There is no method known by which the exact number of 

 bacteria in a sample of milk may be determined, and even when 



* Published in full in " American Journal of Public Hygiene," November, 1907. 



262 



