134 MANUAL OF BACTERIOLOGY. 



the next milking-time.* 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 coK communis 

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

 organisms which contaminate milk are pathogenic only in 

 exceptional cases. Occasionally typhoid fever, cholera, prob- 

 ably scarlet fever, and possibly diphtheria and other diseases 

 are disseminated by means of contaminated milk. In the case 

 of typhoid fever, the milk cans may have been washed with 

 polluted water; after the cans were filled, a few typhoid bacilli 

 left in drops of water in the cans may multiply enormously. 

 Streptococci have been found quite frequently in the milk sold 

 in cities. t The mixture with the milk of non-pathogenic or- 

 ganisms 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. 



Poisoning with milk, ice-cream or cheese is not rare, as is 

 well known. There are many records of whole companies 



* See Harrison and Gumming. The Bacterial Flora of Freshly Drawn Milk. 

 Journal of Applied Microscopy. November, 1902. 



t See Reed and Ward. The Significance of the Presence of Streptococci in 

 Market Milk. American Medicine. February 14, 1903. 



