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BACTERIOLOGY FOR NURSES 



SAMPLE II 



Raw milk 5,400,000 bacteria per c.c. 



J minute pasteurization .... 7,400 bacteria per c.c. 



1 minute pasteurization .... 600 bacteria per c.c. 



The pasteurization of dirty milk containing many millions of 

 bacteria is a rather questionable procedure. The number of 

 microorganisms may be considerably reduced, but all deleterious 

 qualities will not be entirely removed. 



A striking illustration of the beneficial effect of the pasteuriza- 

 tion of milk of an average quality is given below. 



When the children in a New York institution (Randall's Island) 

 were given milk from a selected herd pastured on the island the 

 death rate was as follows : 1 



A pasteurizing plant was installed in the early part of 1898. No other 

 change in diet or hygiene was made. 



Butter. Cream from which butter is to be made is usually al- 

 lowed to sour or " ripen " ; that is, it is purposely allowed to stand 

 in a container two or three days in order that the bacteria present 

 may develop a characteristic flavor and aroma. The process is 

 one of decomposition, but up to a certain point it gives pleasurable 

 and profitable results; beyond that point it is undesirable and 

 offensive. Ordinarily it is stopped at the right moment. The 

 method usually employed is that of allowing the cream to ripen 

 under the influence of any species of bacteria that happen to be 

 present. Occasionally, however, by this " hit or miss " procedure 



1 Adapted from Jordan, "General Bacteriology," 1917, p. 561. 



