BACTERIA IN FOODS l8l 



strate the difference in degree of absorptivity between the 

 two fluids. Yet, whilst this general fact is true, we must 

 emphasise at the outset the possibility and practicability of 

 securing absolutely pure sterile milk. Recently some milk- 

 ing was carried out under strict antiseptic precautions, with 

 the above sterile result. The udder was thoroughly cleansed, 

 the hands of the milker washed with corrosive sublimate and 

 then pure water, the vessels which were to receive the milk 

 had been carefully sterilised, and the whole process was 

 carried out in strict cleanliness. The result was that the 

 sample of milk remained sweet and good and contained no 

 germs. It should be stated that the first flow of milk, wash- 

 ing out the milk-ducts of the udder, was rejected. This 

 fact of the sterility of cleanly drawn milk is not a new one, 

 and has been established by many bacteriologists. Milk, 

 then, is normally a sterile secretion. How does it gain its 

 enormously rich flora of bacteria ? 



Sources of Pollution of Milk. These are various, and de- 

 pend upon many minor circumstances and conditions. For 

 all practical purposes there are three chief opportunities be- 

 tween the cow and the consumer when milk may become 

 contaminated with bacteria: 



1. At the time of milking. 



2. During transit to the town, or dairy, or consumer. 



3. After its arrival. 



Pollution at the Time of Milking arises from the animal, 

 the milker, or unclean methods of milking. It is now well 

 known that in tuberculosis of the cow affecting the udder 

 the milk itself shows the presence of the bacillus of tubercle. 

 In a precisely similar manner all bacterial diseases of the 

 cow which affect the milk-secreting apparatus must inevit- 

 ably add their quota of bacteria to the milk. To this mat- 

 ter we shall have occasion to refer again. There is a further 

 contamination from the animal when it is kept unclean, for 

 it happens that the unclean coat of a cow will more materi- 



