SOURCES OF BACTERIA IN MILK 21 



Somewhat similar results to the above were obtained by H. H. 

 Deane in Canada. We would suggest, however, that such figures 

 as the above be accepted with reserve and only as a general 

 illustration on the point under consideration. 



Pollution at the time of milking arises from the animal, the 

 byre, the milker, or the utensils used for holding the milk. It 

 is now well known that in certain diseases of cows, particularly 

 those affecting the udder, we may find the milk impregnated with 

 pathogenic, putrefactive, and other bacteria. Tuberculosis of the 

 cow affecting the udder is the best known example. According 

 to Klein,^ scarlet fever and diphtheria are diseases which may, 

 under certain circumstances, affect cows and render the milk 

 infective. In ordinary bovine mastitis a well-known organism 

 makes its appearance in the milk. We do not, however, in this 

 place propose to enter into the question of the pathogenic 

 organisms which may occur in milk. We only draw attention 

 to these points in order to establish the fact that any departure 

 from health, any temporary or permanent disease of the cow 

 affecting the milk-secreting apparatus and especially all forms of 

 udder-disease (even slight diseases and eruptions) must inevit- 

 ably add their quota of bacteria to milk. 



But it is not the diseased cow which alone adds bacteria to the 

 milk. A far more extensive pollution due to the cow arises, not 

 from disease, but from uncleanliness. The unclean coat of a cow 

 will more materially influence the number of micro-organisms in 

 milk than either disease or the popularly supposed fermenting food 

 which the animal may eat It is from this external source rather 

 than from the diet that organisms occur in the milk. The dry 

 hairy coat offers many facilities for harbouring dust and dirt. The 

 impurities upon the body of a cow may contain pathogenic as well 

 as saprophytic bacteria, as, for example, when a cow standing in 

 water polluted by sewage is splashed (Axe). The mud and filth 

 of every kind that may habitually be seen on the hinder quarters 

 of cattle all contribute largely to polluted milk. Nor is tljis sur- 

 prising. Such filth contains large quantities of those organic 

 compounds upon which bacteria thrive, and plastered upon cattle 

 at or near the temperature of the blood, nothing is wanting to 

 make it a perfect environment for bacteria. It is impossible for 

 the milker to prevent some of the dust and dirt from the cow finding 



' Annual Report of Medical Officer to Local Government Board, vol. xix. 

 (1890), p. 171. 



