644 Reading-Course for Farmers' Wives. 



growth as soon as the temperature is raised. The production and care 

 of good milk depend very much on the care taken to prevent dust from 

 getting into it, and the maintaining of a low temperature after it is drawn. 

 Last summer, Walter E. King, of the State Veterinary College, and 

 myself, made a number of tests to determine the importance of different 

 sources of milk contamination. In most of these tests, a definite quan- 

 tity of sterilized milk at 98° F. was exposed to some one kind of con- 

 tamination that we wished to test. The milk was then examined, and in 

 that way we could get a fairly accurate idea of what this particular kind 

 of contamination amounted to. Some of the experiments and their re- 

 sults are as follows : 



1. Exposure to air in the stable. — Two liters (about two quarts) 

 of sterilized milk were placed in a sterile pail and exposed seven minutes 

 to the stable air in a passageway behind the cows. This stable was doubt- 

 less cleaner than the average and the air contained less dust than is often 

 found in places where milk is being handled. Immediately after this 

 exposure, the milk was " planted " and we found it to contain 2,800 bac- 

 teria per cubic centimeter (about fifteen drops) ; in other words, between 

 5,000,000 and 6,000,000 bacteria had fallen into the two liters of milk in 

 this short time. 



2. Pouring milk. — When milk is poured from one vessel to another, 

 a very large surface is exposed to the air and great numbers of bacteria 

 are swallowed up. The following tests illustrate this point : About five 

 liters of milk were poured from one can to another eight times in the 

 stable air. It was found, after pouring, that this milk contained prac- 

 tically 100 bacteria per cubic centimeter more than it contained before 

 pouring ; in other words, about 600,000 bacteria had gotten into the milk 

 on account of this exposure. 



In another similar experiment, when there w'as a little more dust in 

 the air, the contamination due to pouring eight times was two and one- 

 half times greater than in the preceding experiment. 



The importance of pouring milk as little as possible from one vessel 

 to another has suggested to Dr. J. Roby of the Rochester Health Depart- 

 ment that milking pails should be made larger than those now used and 

 immediately closed after the cow^ has been milked. The milk should then 

 be cooled and delivered in these same pails without further exposure. In 

 some ways this suggestion is a most excellent one, and it may be that 

 under certain conditions, the disadvantages of this method of handling 

 milk would exceed the advantages. 



3. Contaminated iite)isils. — IMuch contamination of milk results 

 from putting it into dishes that have been cleaned and then exposed 

 wdierc dust can fall into them. In experiments to determine what this 



