THE EXAMINATION OF MILK 319 



THE EXAMINATION OF MILK. 



From the fact that milk forms such an excellent nutrient 

 material for the growth of nearly all bacteria, it follows 

 that this article of food is almost invariably contaminated 

 with bacteria from various sources. The milk in the udder 

 of a cow in perfect health is absolutely free from micro- 

 organisms, but when the cows are suffering from disease, 

 the milk as it leaves the udder may contain the tubercle or 

 other pathogenic organisms which may be, and generally 

 are, the specific cause of the particular diseased condition. 

 It is unquestioned that many diseases,, such as scarlet fever, 

 typhoid, tuberculosis, diphtheria, etc., are in very many 

 cases conveyed by milk. Sources of infection are to be 

 found in the many insanitary conditions which surround 

 the milk-supplies in many parts of the country. The cow- 

 sheds in which the cows are milked are usually saturated 

 with excremental filth, the animals themselves are kept in 

 a very dirty condition, their hind-quarters and udders are 

 frequently soiled with dejecta, as is also the straw on which 

 the animals stand, which in itself forms an admirable 

 forcing-ground for micro-organisms. Other sources of 

 contamination are want of personal cleanliness on the part 

 of the milkers, and dirty dairy utensils, which are possibly 

 ' cleaned ' out with water from a surface- well which is pro- 

 bably polluted with farmyard drainage. Again, other risks of 

 bacterial contamination are introduced by want of proper 

 care and sanitary precautions when consigning the milk to 

 the consumers. The milk is cooled in open ' coolers ' ; it 

 is sent long railway journeys in loosely-covered churns, and, 

 lastly, is exposed for a considerable period of time on 

 counters in open vessels exposed to all kinds of street dirt 

 and dust. 



