206 Dairy Bacteriology. 



1. The caps of all bottles containing milk of grade C 

 hall be white and shall contain in red the words ' ' Grade 

 C" in large type and "for cooking" in plainly visible 

 type. 



2. Cans containing milk of grade C shall be painted 

 red on necks and shoulders and shall have in red the 

 words "Grade C" in large type and the words "for 

 cooking" in plainly visible type affixed to each can. 



All creameries handling milk of different grades will 

 l)e required to demonstrate to the Department of Health 

 that they are capable of keeping the grades separate, 

 and must keep records satisfactory to the Department 

 of Health concerning the amount of milk of each grade 

 handled each day. 



It is to be noted that the grades of milk are based on 

 the bacterial content of the milk and on the opportunity 

 for the milk to become contaminated with pathogenic 

 organisms. From the statements made in a previous 

 chapter it is evident that the number of bacteria in 

 any sample of milk is dependent upon (1) the original 

 amount of contamination, (2) the age of the milk, and 

 (3) the temperature at which it has been held. A high 

 bacterial content is indicative of poor milk, while a low 

 bacterial content can be obtained, in the case of raw 

 milk r only where due attention is paid to cleanliness and 

 cooling. This relation between the quality of milk and 

 its bacterial content has led many cities to adopt numer- 

 ical bacterial standards, even when grades of milk have 

 not been established. Boston requires that the milk 

 shall not contain more than 500,000 bacteria per cubic 

 centimeter. Rochester, N. Y., has a standard of 100,000 

 per cubic centimeter, while Chicago requires that the 

 milk on arrival in the city shall not contain more than 



