CONTAMINATION OF FOODS 137 



once introduced, they can not be removed therefrom as 

 from the surface of a solid. 



The source of contamination of foods in general is readily 

 traced to contact with matter from the soil, water, or the 

 contents of the alimentary tract of animal life. These ma- 

 terials harbor the bacterial life that is the cause of the 

 changes involved, and if foods can be kept from direct con- 

 tact with such organic wastes, it is comparatively easy to 

 prevent in large measure the decomposition changes that 

 will otherwise occur. In the protection and care of food 

 products, it is desirable to do only those tilings that are of 

 real necessity and value, rather than to waste time and 

 effort in carrying out a mode of procedure that is unneces- 

 sarily refined. So much exaggeration is frequently found 

 in the public prints, relative to germ life and its dangers, 

 that not infrequently unnecessary alarm is engendered in 

 the minds of many people. This makes it important that 

 consideration be given to the various sources of contamina- 

 tion from which milk becomes seeded with bacteria. It is 

 especially essential that the relative importance of the vari- 

 ous sources of contamination be understood, for if improve- 

 ment of the product is to be attempted, the first efforts 

 should be directed to those sources from which the greatest 

 return for money and labor expended will be obtained. 



All milk will contain bacteria, no matter how carefully it 

 may be produced. It is impossible to maintain the same 

 standards of cleanliness in the stable as in the kitchen, the 

 bakery, and the meat-shop. More than any other food, 

 milk is subject to contamination with materials rich in bac- 

 teria. 



Contamination of milk from the interior of the udder. 

 When milk leaves the milk-producing cells of the udder of 

 a healthy animal, it is probably free from these organisms; 

 but this condition does not long obtain, for before it is 



