PRACTICAL DAIRY BACTERIOLOGY 



Need of Public Inspection. The recognition of the close asso- 

 ciation between the purity of the milk supply and public health 

 has given rise to a large amount of work on the part of health 

 boards and others directed toward the control of the milk supply. 



There is no food more easily adulterated than milk. Water 

 can be added to it, and a variety of disinfectants and preserva- 

 tives can be put in it without the consumer having any suspicion 

 of it. For this reason the regulation of the milk supply has 

 demanded a special set of rules quite different from those ap- 

 plicable to other foods. The individual is quite incapable of 

 protecting himself, and he must, therefore, depend upon the 

 expert knowledge of public officials, whom he must appoint for 

 the purpose. The difficulty of the problem has rendered the 

 methods of inspecting and controlling the public milk supply 

 still more or less uncertain and tentative. Some of the rules 

 and regulations that have been adopted and are now in force 

 are undoubtedly of high importance, and some probably are 

 mistakes which will be corrected as more information and better 

 ideals prevail. The ends to be reached by a public control of 

 the milk supply are three: i. Chemical purity. 2. Freedom from 

 specific disease germs. 3. Clean milk. 



CHEMICAL PURITY 



We are not concerned here with chemical problems, and the 

 matter of chemical purity is mentioned here only because the, 

 same set of officials are likely to be called upon to consider 

 chemical and bacteriological problems. The methods of testing 

 milk may be found in books designed for that purpose. At this 

 point it is only necessary to state that the chemical purity of 

 milk is fairly well insured by public milk inspection. The dif- 

 ferent states have different laws as to the standard which a pure 

 milk should reach, and they are in general so efficiently en- 

 forced that the public milk suoply has a very fair grade of 

 chemical purity. 



