PUBLIC PROBLEMS 173 



sible to obtain except by sterilizing, it follows that all market 

 milk will contain some bacteria. Hence it is necessary, if this 

 is to be our means of determining quality, to set a standard as 

 to the number of bacteria that may be legitimately found in 

 proper market milk. How large a number is consistent with 

 the proper condition of the milk when it is placed upon the 

 market ? 



PUBLIC CONTROL OF THE MILK SUPPLY 



The growing recognition of the dangers in the milk supply 

 and the inability of the individual to handle the problem for 

 himself has led to a demand that the public health officials shall 

 in some way guarantee the purity and healthfulness of the 

 whole supply. The necessity for such a control is apparent, but 

 it is not so evident how it can be brought about. Three quite 

 different methods of reaching the end have been advocated: 

 i. The use of standards. 2. Dairy inspection. 3. Compulsory 

 pasteurisation. 



THE USE OF STANDARDS 



Milk standards may be arbitrarily fixed for chemical and 

 bacteriological purity, and by constant analysis the dairies or 

 dealers that fail to reach the standard may be determined. For 

 chemical purity this works fairly well. For bacterial purity its 

 value is not so clear, for even after a standard has been set, 

 the enforcing of it is difficult and of doubtful wisdom. 



Numerical Bacterial Standard. The actual numbers of bac- 

 teria found are very great in the milk of large cities. In 

 Chicago, a long series of tests showed it to range from 100,000 

 to 1,000,000 per c.c. ; in New York, from 250.000 to 5,000,000; 

 in Baltimore, from 1,500,000 to 4,500,000. The milk delivered 

 to factories ranges from 5,000,000 in winter to 30,000,000 in 

 summer. In small towns and cities the average is considerably 

 lower than in the larger cities because of nearness to the source 



