CHAPTER XIII 



MILK; EGGS; PTOMAINE POISONING 

 BACTERIA IN MILK 



It is more difficult to preserve a supply of good milk 

 than of almost any other food product. This is due to 

 three reasons : (i) The number of bacteria, under ordinary 

 circumstances, is greater than in any other food product. 

 (2) Milk furnishes an exceptionally favorable food for 

 bacteria. (3) The changes which these bacteria produce in 

 milk are very decided and take place with great rapidity. 

 These three factors together make it difficult to preserve 

 milk in the household without exceptional precautions. 



The bacteria present in milk are not only numerous, 

 but they comprise many kinds (Fig. 66). Milk as it is 

 secreted by the healthy cow does not contain bacteria, but 

 it has a chance of contamination with microorganisms 

 from a variety of sources, and even a few moments after 

 the milk has been drawn it contains organisms in large 

 numbers. The chief sources of these organisms are : 

 (i) the bacteria in the milk ducts which are washed into 

 the milk can during the milking ; (2) the dust that is likely 

 to be floating in the air of the barn or milking stall where 

 the milk is drawn ; (3) the milk vessels, which are rarely 

 washed perfectly clean ; (4) the dirt and filth that are 

 always clinging to the hairs of the cow and which fall into 



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