DEVELOPMENT OF CITY MILK SUPPLY PROBLEMS 49 
There can be no question regarding the relative ease and 
accuracy with which the above outlined examinations will give 
the facts regarding the food value, freedom from germs of 
infectious diseases, and cleanliness of a sample of milk. How- 
ever, there is not the same agreement regarding the possibility 
of determining the keeping quality. There are at present no 
means available for quickly measuring the keeping quality 
of milk except in samples which are rapidly approaching an 
undesirable condition. In such samples titration of the 
acidity may indicate their condition and in the case of un- 
pasteurized milk a microscopic examination is even more 
useful. However, the results from both such examinations 
of some milk samples may seem favorable and still the milk 
may not remain sweet for twenty-four hours under household 
conditions. 
In the absence of any test which will immediately yield the 
desired information in the case of pasteurized milk, recourse 
may be had either to the bacterial count or to the observation 
of a sample of the milk itself. Since the question at issue is 
the ability of the milk to remain sweet and in satisfactory 
condition for twenty-four or at most forty-eight hours, this 
fact can be determined from the sample of the milk itself 
quite as quickly as the bacterial count can be determined from 
the standard plates. The examination of the sample has the 
added advantage that it does not require as extensive equip- 
ment nor as delicate manipulation. Most important of all, 
it gives precisély the information desired while the bacterial 
count even when accurately determined must first be trans- 
lated before it can be of service. 
Following the plan above outlined it is practicable to collect 
samples of the milk as delivered to the consumer and from 
the examination of such samples, supplemented by some 
inspection of pasteurization plants, determine the food value, 
healthfulness, cleanliness, and keeping quality of the milk 
supply. 
