PASTEURIZATION 215 



est cow's milk that can be obtained. Whether this is to be 

 modified, pasteurized, or otherwise treated is a question 

 for the doctor to decide in each individual case. 



For adults and for children over two years of age there 

 can be no more objection to the heating of milk than there 

 is to the broiling of a beefsteak. The heating of the milk 

 does not materially change its nutritive or digestive value; 

 in fact, milk heated to a temperature just sufficient to kill 

 the harmful bacteria cannot be distinguished from raw 

 milk by its flavor or appearance, or by laboratory tests. 



Babies who cannot get the best quality of cow's milk 

 should receive protection through pasteurization, especi- 

 ally in the summer-time. 



The relation of dirty milk to infant mortality demands 

 separate consideration. 



Park and Holt ^ studied groups of iaf ants in the tenement 

 houses and institutions in New York for periods of about 

 three months in the summers of two years (1902-03). This 

 work is the most important evidence we have on the sub- 

 ject, for it combines careful clinical observation with labora- 

 tory studies. Although the number of cases was compara- 

 tively small, the results obtained were almost identical 

 during the two summers, and indicate that even fairly pure 

 milk, when given raw in hot weather, causes illness in a 

 much larger percentage of cases than the same milk given 

 after pasteurization. A considerable percentage of infants, 

 however, did apparently as well on raw as on pasteurized 

 milk. Park and Holt include in part: — 



The number of bacteria which may accumulate before milk 

 becomes noticeably harmful to the average infant in summer 

 difiFers with the nature of the bacteria present, the age of the milk, 

 and the temperature at which it has been kept. When milk is 



' Park, William H., and Holt, L. Emmett, "Report upon the results 

 with different kinds of pure and impure milk in infant feeding in tenement 

 houses and institutions of New York City: A clinical and bacteriological 

 study," Medical News, vol. 83, 1908, p. 1066. 



