No. 4.] SOURING OF MILK. 249 



if the number of bacteria is reduced to a minimum to begin 

 with, and then if the milk is promptly cooled with ice or 

 spring water to 55° or below, the keeping qualities of the 

 milk will be greatly increased, and there will be no trouble 

 from sour milk in the ordinary course of getting it to con- 

 sumers. One authority says that by these precautions milk 

 may be kept merchantable a week or ten days. This is of 

 the utmost importance to farmers, particularly those who 

 ship milk to cities. 



The whole "secret" of avoiding sour milk trouble is in 

 three words, — cleanliness, prompt cooling. With these 

 milk will withstand even the traditional influences of the 

 thunder shower. 



The lirst source of the infection of milk with the bacteria 

 of souring seems an exception to the above general state- 

 ment. These bacteria get into the milk pail in the first few 

 drops drawn from the udder. At the close of the previous 

 milking a little milk is always left at the end of the teat, 

 a drop often remaining in the little orifice near the end of the 

 teat. Here the bacteria multiply to an enormous extent, 

 the warmth of the animal body furnishing excellent condi- 

 tions for their increase. When the next milking Is com- 

 menced they are washed into the pail to contaminate the 

 whole of the milking and shorten its life. A material in- 

 crease of the keeping properties of milk will follow from 

 milking on the floor the first streams from each teat, enough 

 to rinse them out. 



The next and most common source of infection is through 

 the air which is always loaded with bacteria. The number 

 of bacteria in the air varies very largely, but the germs are 

 more numerous in inclosed spaces like rooms than in the open 

 air. Hence, when cows are milked in the barn the milk will 

 have more bacteria than when they are milked in the open 

 field. We cannot tell all of the ways in which these bacteria 

 get into the air, but we do know that they come from parti- 

 cles of manure, skin, food, hair, threads and cobwebs. They 

 are intimately associated with the dust floating in the air. 

 From the body of the animal, the hands of the milker or his 

 clothes may also come the troublesome little "Imgs." Hence 

 the more filthy the conditions the more bacteria and the sooner 



