Bacteriology of the Household. 73j 



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, but it may be that 

 under certain conditions, the disadvantages of this method of handling 

 milk, would exceed the advantages. 



3. " Contaminated utensils. — Much contamination of milk results from 

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

 dust can fall into them. In experiments to determine what this kind of-' 

 contamination amounts to, it has been found that when little 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 

 sterilized. 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 numbers 

 of bacteria. It was found that the milk in the pail which was not pro- 

 tected 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. 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, con- 

 tained 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 reason- 

 able precautions? The easiest way known is to use a small-top milking 



