28 MODERN DAIRY PRACTICE. 



While we cannot hope to make a raw product of abso- 

 lute keeping qualities in dairying, we must try to make 

 it keep as long as possible, i.e., we must protect the milk 

 from being spoiled by bacteria by all means at our dis- 

 posal. 



Precautions against Infection of Bacteria. The pre- 

 cautions used against infection of bacteria are of two 

 kinds, (1) such as aim at the protection of the milk from 

 infection from without', and (2) such as aim to check the 

 development and multiplication of the micro-organisms 

 already found in the milk. In practical work these two 

 methods go hand in hand, however, for which reason we 

 shall not here attempt a strict separation. 



Infection during Milking, The milk is exposed to 

 infection from the moment it is drawn from the udder. 

 Being pressed out of the teats in a fine spray, it comes in 

 contact with the air on a very large surface ; the air in 

 the cow-stable, and especially under the udder region of 

 the cow, is nearly always filled with such bacteria as are 

 the feudal enemies, so to speak, of the milk. If the 

 milking is done in the open air, e.g., in the pasture, the 

 danger of infection is of course less. It can easily be 

 shown by a bacteriological examination, however, that 

 there is a danger also in this case. By the shaking to 

 which the udder and the parts of the skin next to the 

 same are subjected in milking, bacteria are always loosened 

 in large numbers and infect the air and the milk. This 

 is plainly shown by the following simple experiment : 



Of two sterilized culture-plates with nutritive gelatine, 

 which had been freed from all bacterial life by steriliza- 

 tion, one was placed five to six feet away from the milker 

 and the cow, and the other directly under the udder, 



