46 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



terms are very indefinite and have been frequently used 

 indiscriminately. Since 1893, milk produced under the 

 supervision of a medical milk commission has been sold 

 under the name of certified milk, but the term has also 

 been applied to milk which was not produced under these 

 conditions. The desirability of defining the special 

 names used for milk, and the advantage to both the pro- 

 ducer and consumer of grading or classifying market 

 milk according to its hygienic quality, has long been 

 recognized, but no definite steps were taken in the matter 

 until 1907 when Melvin 1 proposed that market milk 

 be graded in three classes, as follows : 



Class 1. Certified Milk. This may be briefly defined as milk 

 produced in accordance with the requirements of the American 

 Association of Medical Milk Commissions (see Appendix). 



Class 2. Inspected Milk. This term should be limited to 

 clean raw milk from healthy cows, as determined by the tuber- 

 culin test and physical examination by a qualified veterinarian. 

 The cows are to be fed, watered, housed, and milked under good 

 conditions, but not necessarily equal to the conditions provided 

 for Class 1. All persons who come in contact with the milk 

 must exercise scrupulous cleanliness, and must not harbor the 

 germs of typhoid fever, tuberculosis, diphtheria, and other in- 

 fections liable to be conveyed by the milk. This milk is to be 

 delivered in sterilized containers, and is to be kept at a tempera- 

 ture not exceeding 50 F. until it reaches the consumer. It shall 

 contain not more than 100,000 bacteria per cubic centimetre. 



Class 3. Pasteurized Milk. Milk from the dairies not able 

 to comply with the requirements specified for Classes 1 and 2 

 is to be pasteurized before being sold, and must be sold under 

 the designation " pasteurized milk." Milk for pasteurization 

 shall be kept at all times at a temperature not exceeding 60 F. 

 while in transit from the dairy farm to the pasteurization plant, 



1 24th Annual Report, U. S. Bureau of Animal Industry, 

 pp. 179 to 182. 



