DISTRIBUTION OF BACTERIA. 145 



in the milk-ducts and in the lower part of the teat in which 

 numerous bacteria will have developed before the next 

 milking-time. 1 The first milk obtained at a milking should 

 therefore be discarded, as it may contain an excessive 

 number of bacteria. 



Contamination with bacteria may occur from the outer 

 surface of the udder of the cow, the hands of the milker or 

 dirty pails, or through agitation of the air of the stable, and 

 in other ways readily conceived of. Bacillus coli commu- 

 nis is often found in milk. Excluding the tubercle bacillus, 

 the organisms which contaminate milk will be pathogenic 

 only in exceptional cases. Occasionally typhoid fever, 

 cholera, and possibly scarlet fever, diphtheria and other 

 diseases are disseminated by means of contaminated milk. 

 In the case of typhoid fever, it is probable that the milk cans 

 have been washed with polluted water; after the cans were 

 filled, a few typhoid bacilli left in drops of water in the 

 cans, might multiply enormously. Streptococci have been 

 found quite frequently in the milk sold in cities. 2 The 

 mixture with the milk of non-pathogenic organisms from 

 the air, and their growth, may induce changes in it which 

 render it unfit for consumption, and even poisonous. These 

 alterations may be evident to the senses, as the ordinary 

 lactic acid fermentation (souring of milk), or they may not. 

 The character of the alterations doubtless varies much with 

 the temperature and with the character of the contaminating 

 bacteria. Summer temperatures of course favor decom- 

 position and fermentation. Specialists in children's diseases 

 attribute to alterations in milk with the formation of poison- 

 ous substances a preeminent influence in the production of 

 the intestinal disorders of infancy so common in the summer. 



1 See Harrison and dimming, " The Bacterial Flora of Freshly 

 Drawn Milk," Journal of Applied Microscopy, November, 1902. 



2 See Reed and Ward, " The Significance of the Presence of Strepto- 

 cocci in Market Milk," American Medicine, February 14, 1903. 



