The Farm Table. 645 



kind of contamination amounts to, it has been found that when httle care 

 is taken to protect the dishes, the milk will often contain several hundred 

 times as many bacteria as when the utensils were protected from dust. In 

 order to illustrate this point, two pails were carefully washed and steril- 

 ized. One of them was covered with sterile cloth to keep dust from 

 falling into it. The other was left exposed to the air of a clean creamery 

 for only a few minutes. A small quantity of sterile milk was then put 

 into each pail, rinsed around and then examined for the number of bac- 

 teria. It was found that the milk in the pail which was not protected 

 from dust, contained 1600 more bacteria per cubic centimeter than the 

 milk in the protected pail. 



4. Contamination from the cow's udder and body. — Great numbers 

 of bacteria fall into the milk when it is being drawn from the udder, be- 

 cause the milking pail is directly under the udder which is being shaken 

 more or less by the milker's hands. This kind of contamination may be 

 reduced by cleaning the udder. For example, it was found that sterile 

 milk exposed under the udder as long as it takes to milk a cow and while 

 the udder was being shaken about the same as when milk is being drawn, 

 contained 19,000 bacteria per cubic centimeter. In this case the udder 

 had been wiped off with a dry cloth much in the same way as is done in 

 fairly good dairies. 



In a similar test, the udder was wiped with a damp cloth and then 

 the number of bacteria was reduced to 4,500 per cubic centimeter. In a 

 third experiment the udder was wiped with a cloth dampened in a 4 per 

 cent carbolic acid solution ; then the number of bacteria was 3.200 per 

 cubic centimeter. In cases in which no particular care is taken to clean 

 the udder, the bacteria getting into the milk from this source may run up 

 into the hundreds of thousands or millions. 



5. Importance of small openings in milk pails. — Thus it is seen that 

 it is impracticable to clean the udder or free the air from dust so per- 

 fectly that no bacteria will fall into the milk. The next question is, how 

 can we reduce the number of those that will fall in spite of all reasonable 

 precautions ? The easiest way known is to use a small top milking pail. 

 Reduce the opening through which dirt can fall into the pail. An experi- 

 ment was carried on to illustrate this point, and it was found that milk 

 drawn in an ordinary milking pail contained 1,300 bacteria per cubic cen- 

 timeter, while that drawn in a pail with opening about one-half as wide, 

 contained only 320 bacteria per cubic centimeter. This is just what we 

 would expect when we compute the number of square inches through 

 which dust can fall into the different kinds of pails. For example, a pail 

 having a top 14 inches in diameter has an opening of 153.86 square 

 inches; a pail with 12-inch top has an opening of 113.04 square inches; 



