RELATION OF I5ACTKKIA To THK DAIRY. 183 



These suggestions are not simply theoretical but have proved 

 to be distinctly practical. Careful scientific testing has shown 

 that the number of bacteria may be reduced and the keeping 

 property of the milk much increased merely by applications of 

 the simplest devices for cleanliness. Sometimes, where ex- 

 ceptional care is given along the lines suggested, milk has been 

 obtained that is nearly sterile. Further, it is not only in scien- 

 tific experiments, but in actual dairies that these simple pre- 

 cautions for cleanliness have worked great improvements. 

 Wherever a dairy has taken a pride in producing good milk and 

 has attended to the matter of cleanliness, the effect is immedi- 

 ately manifest in a reduction of the bacteria. There is a very 

 great difference in the number of bacteria and the consequent 

 keeping quality of milk from well-kept, clean dairies and from 

 slovenly kept dairies. Indeed, the bacteriologist is commonly 

 able to give a very accurate judgment as to the condition of a 

 dairy and its cow sheds, by simply making a bacteriological 

 examination of the milk. The suggestions as to cleanliness 

 are thus not simply the theoretical advice of the bacteriologist 

 but the result of an abundance of practical experience. 

 Cleanliness is the first precaution which must be taken by a 

 farmer who desires to produce good milk. 



Cooling. The second factor of importance in the keeping 

 quality of milk, of more importance even than cleanliness, is 

 the matter of temperature. The actual number of bacteria 

 which get into the milk during milking is important, but it is 

 of less importance than their rate of multiplication in the next 

 few hours. Bacteria grow very rapidly at high, and very 

 slowly at low temperatures. Milk, when drawn from the cow, 

 is at a temperature most favorable for the greatest growth. 

 Moreover the milk contains an ideal food for most species of 

 bacteria, nearly all saprophytes flourishing wonderfully upon 

 milk. As a result, the bacteria that get into the milk during 

 the milking begin to grow with great rapidity. So long as the 



