Bacteria in Market Milk. 207 



1,000,000 per cubic centimeter from May first to Sep- 

 tember thirtieth, and not over 500,000 between October 

 first and April thirtieth. The sale of milk containing 

 more than 3,000,000 bacteria per cubic centimeter is 

 prohibited. 



It has been urged that bacterial standards are not of 

 value since the healthfulness of milk depends on the kind 

 of bacteria present rather than on the number. It is 

 well recognized that milk containing millions of acid- 

 forming organisms, butter milk, is a healthful food, 

 while that containing many less bacteria may contain 

 some disease-producing organisms. It has been urged 

 that a qualitative standard should supplant the quanti- 

 tative. The consumer desires milk that has been pro- 

 duced under clean conditions, and which has good keep- 

 ing qualities. The harmless forms of bacteria exert the 

 greatest influence on the keeping quality. Experience^ 

 has shown that the quantitative examination of the milk 

 supply as it comes from the farm is the most feasible 

 method of determining, in the laboratory, whether the 

 farmer has obeyed the rules with reference to cleanli- 

 ness and cooling of the milk. The bacteriological ex- 

 amination also gives an indication as to whether the 

 large number of bacteria is due to gross contamination 

 of the milk with mud and manure, or actual growth of 

 bacteria as in old milk. In the latter case the ordinary 

 acid-forming bacteria will usually predominate in the 

 milk, while in the former, the number of kinds of bac- 

 teria and the proportion between the kinds will be 

 changed. It is of course evident that the quantitative 

 standards should be applied with judgment. 



It is also claimed that the delay in securing the re- 

 sults in the quantitative examination of milk is an ob- 



