Contamination of Milk. 59 



dent at time of milking, it is in all probability due to 

 character of feed consumed, or possibly to medicines. 

 If, however, the intensity of the taint grows more pro- 

 nounced as the milk becomes older, then it is probably 

 due to living organisms which require a certain period 

 of incubation before their by-products are most evi- 

 dent. 



Moreover, if the difficulty is of bacterial origin, it 

 can be frequently produced in another lot of milk 

 (heated or sterilized is preferable) by inoculating the 

 same with some of the original milk. Not all abnormal 

 fermentations are able, though, to compete with the 

 lactic acid bacteria, and hence outbreaks of this sort 

 soon die out by the re-establishment of more normal 

 conditions. 



Factory contamination. As the time element is of 

 importance in the production of troubles due to bac- 

 teria, it follows that infection of milk on the farm is 

 fraught with more consequence than factory contami- 

 nation, as the organisms introduced would have a 

 longer period of development. Nevertheless, the con- 

 ditions in the factory are by no means to be ignored, 

 as they not infrequently permit the milk to become 

 seeded with highly undesirable types. A much more 

 rigid control can be exercised in the factory, where 

 steam is at hand as an aid in the destruction of organ- 

 isms. In the cleaning of pumps and pipes, steam is 

 absolutely necessary to keep such apparatus in a sani- 

 tary condition. 



The water supply of the factory is a matter of prime 

 importance, as water is used so extensively in all fac- 

 tory operations. When taken from a shallow well, es- 



