243 



Sedgwick and Batcheldor found in milk from the Boston 

 milk supply an average of 2,335,500 bacteria per c.c. in 57 

 samples of milk. Sixteen samples of milk collected from 

 groceries in Boston contained 4,577,000 per c.c, and those 

 samples obtamed from "well-to-do families on the Back Bay " 

 contained an average of 1,438,000. 



Sedgwick found that sewage of Lawrence, Mass., contained 

 from 100,000 to 4,000,000 bacteria per c.c. 



Bitter places the maximum limit for milk fit for human 

 food at 50,000 bacteria per c.c, and Buffalo puts the limit at 

 10,000 per c.c. 



The above examples of quantitative bacteriological analysis 

 show that the greater the tilth surrounding the milking, the 

 more the milk is handled or changed from vessel to vessel 

 and exposed to germ-laden air, and the older the milk, the 

 greater the number of the bacteria in the milk. In order to 

 obtain pure milk, cleanliness must begin with the barns, cows, 

 vessels and milkers before the milk is drawn, and be continued 

 during the milking and throughout all the processes of 

 handling the milk. Furthermore, the milk must be kept at or 

 below 45 degrees F. Cleanliness is the great means of 

 preventing bacterial contamination. Continuous vigi- 

 lance along the line of cleanliness is the price of pure, 

 clean, wholesome milk. 



The question of the kind of bacteria is very important in 

 most instances, and somewhat indifferent in other cases. As 

 long as the number of ordinary bacteria in milk is low they 

 do not seriously injure the milk, unless the bacteria are dis- 

 ease-producing, or they injure the products (butter, cheese) to 

 be mide from the milk;. There are germs, such as Conn's 

 "Bacillus No. 41," that are valuable because they act in such a 

 manner as to produce a pleasant flavor and aroma in the butter 

 made from the milk. Likewise there are useful bacteria 

 which produce an agreeable flavor and chemical change in 

 cheese. But, as a rule, all bacteria that grow and multiply 

 extensively in milk or cream which is to be used without 

 change as human food, injure more or less its nutritive value. 

 There is possibly one exception to this general statement, but 



