44 SOURCE OF BACTERIA IN MILK. 



found that, upon one day, when the feeding was allowed to 

 take place shortly before the milking, not only did the number 

 of bacteria in the milk rise markedly, but the milk was filled 

 with a species quite different from those which were found in 

 the same barn under ordinary conditions. The use of the 

 particular food in question jusf before milking had totally 

 modified the character of the bacteria found in the milk. 



The Milk Vessels. A further source of contamination is 

 the vessel into which the milk is drawn. Under the ordinary 

 conditions this is a large source of contamination, for upon 

 the ordinary farm it is practically impossible to wash the 

 milk vessels in such a way that they will be bacteriologically 

 clean. The most thorough washing that may be given 

 them in hot water, N such as is commonly available on the 

 farm, is insufficient to wash out the bacteria. After such a 

 washing many bacteria will remain in the vessel, attached to 

 its sides and walls, and, although drying between the suc- 

 cessive milkings, they are not at all injured and are ready 

 to begin to feed, to grow and multiply, as soon as the pail 

 is again filled with milk. The more thorough the washing, 

 the less the chance of contamination from this source, but 

 except by the use of liv^e steam, which is rarely available on 

 the farm, the milk vessels can hardly be washed absolutely 

 clean. This source of contamination is, therefore, one which 

 the dairyman must always expect and for which he must 

 make allowance. 



The Milker. A source of contamination that is quite liable 

 to be one of more serious importance is the milker. The 

 pathogenic bacteria which are capable of producing diseases 

 in man are more liable to be found associated with the milker 

 than they are with the cow, and contamination of the milk, 

 during the milking, by bacteria from the milker's hands or 

 clotking is, therefore, more likely to affect the wholesomeness 

 of the milk than the bacteria from other sources. The 

 hands and clothing of the milker are the two chief sources 



